Mass timber panel connectors and assemblies, and methods related thereto

Abstract

Mass timber (MT) panel connectors are provided that include a first bearing portion configured to affix to a first MT structural member, a second bearing portion configured to affix to a second MT structural member, and a fuse portion extending between the second bearing portion and the first bearing portion. The first bearing portion extending from a first end towards a second end. The second bearing portion extending from the second end towards the first end. The fuse portion is configured to plastically yield when an overload is transferred between the first bearing portion and the second bearing portion. MT constructions assemblies are also provided that include structural members that are connected by a plurality of MT panel connectors.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 761,981, filed February 23, 2025, the entirety of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] The subject matter of the present disclosure relates generally to the field of mass timber construction. More particularly, the present disclosure relates to connectors in mass timber construction.BACKGROUND OF THE INVENTION

[0003] Mass timber (MT) and wood construction are ubiquitous in the US, known for its cost-effectiveness and for the fact that it requires the least specialized training relative to other materials. The National Design Specification (NDS) provides strength capacity values for wood members, including for typical connections such as nails, screws, and bolts.

[0004] In recent years, a new technology of engineered MT products and construction technologies has developed, known as cross-laminated timber (CLT). Whereas common wood construction comprises relatively slender elements, CLT is used to form panels by gluing the slender elements in layers where the elements in each layer are perpendicular to the adjacent layers. Such panels may be used for multiple building applications, such as floor planks, walls, or deep beams.

[0005] In building construction, it is necessary to connect CLT planks to other members of the building. This is conventionally done using steel plates that connect the two planks using dowel connectors such as large numbers of bolts or screws. These relatively small fasteners are often the weakest link in typical assemblies and do not develop the strength of the connected member.

[0006] In structural design in general, there is consideration for the possibility of overload. This is managed by inflating estimated demands and restricting available member capacity, thereby minimizing the chances of overload. Typically, the magnitude of capacity reduction accounts for uncertainty in the controlling mechanism, that is, the link in the chain of members and connections would fail first; mechanisms with greater dispersion in tested capacity require greater reduction in order to achieve a consistent level of confidence.

[0007] In current practice, CLT construction is characterized by few, large, prefabricated, strong panels joined by many small connectors requiring significant labor on the construction site. In an overload condition, it is unclear what mechanism would control the design, but it appears that few elements in the system have means to deflect in a stable manner without loss of strength (i.e. yield), which would provide occupants the warning sign before catastrophe might occur.SUMMARY OF THE INVENTION

[0008] In one aspect of the present disclosure, a mass timber (MT) construction assembly is provided that includes a first structural member being elongated along a first mating surface having plurality of first connection holes for receiving a plurality of MT panel connectors. The plurality of first connection holes includes a first hole formed from a first bearing surface and first non-bearing surface. The first non-bearing surface is positioned between the first bearing surface and the first mating surface. The MT construction assembly further includes a second structural member connected to the first structural member by the plurality of MT panel connectors to form a portion a framed structure. One or both of the first structural member and second structural member is a MT structural member. The second structural member is elongated along a second mating surface having a plurality of second connection holes for receiving the plurality of MT panel connectors. The plurality of second connection holes comprising a second hole formed from a second bearing surface and second non-bearing surface. The second non-bearing surface being positioned between the second bearing surface and the second mating surface. The first structural member and the second structural member are arranged such that first mating surface contacts the second mating surface and such that the first hole and the second hole are aligned and such that the first non-bearing surface and second non-bearing surface define a free-movement volume. The MT construction assembly further includes a first MT panel connector of the plurality of MT panel connectors. The first MT panel connector connecting the first structural member to the second structural member. The first MT panel connector includes a first bearing portion affixed to the first bearing surface of the first hole, a second bearing portion affixed to the second bearing surface of the second hole, and a fuse portion extending within the free-movement volume and being non-affixed to the first non-bearing surface and second non-bearing surface. The fuse portion is configured to plastically yield within the free-movement volume when an overload is transferred between the first bearing portion and the second bearing portion. The overload causes relative movement between the first structural member and the second structural member such that the first hole and second hole become unaligned while the first bearing portion and second bearing portion respectively do not dislodge from the first bearing surface and the second bearing surface.

[0009] In an embodiment, the fuse portion includes a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion, wherein the fuse portion includes a cross-sectional area that varies between the first tapering portion and the second tapering portion. The cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion.

[0010] In an embodiment, the first bearing portion and second bearing portion include cylindrical surfaces. The first tapering portion and second tapering portion include cylindrical-conical shapes.

[0011] In an embodiment, the first bearing portion and second bearing portion include rectangular surfaces. The first tapering portion and second tapering portion comprise trapezoidal prism surfaces.

[0012] In an embodiment, the first bearing portion and second bearing portion include elliptical surfaces. The first tapering portion and second tapering portion comprise elliptical-conical shapes. In an embodiment, the first structural member is formed from CLT and the first bearing surface is formed from a first sleeve affixed within the first hole.

[0013] In an embodiment, the first structural member is formed from CLT and the first bearing portion of the first MT panel connector is bonded to the first bearing surface.

[0014] In an embodiment, the first structural member is formed from CLT and the first bearing portion of the first MT panel connector is press-fit with the first bearing surface.

[0015] In an embodiment, the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

[0016] In an embodiment, the first structural member and the second structural member each include a CLT panel and form a portion of a wall extending from a floor, and the first mating surface and the second mating surface are parallel to the floor.

[0017] In an embodiment, the first structural member and the second structural member each include a CLT panel and form a portion of a shear wall extending from a floor, and the first mating surface and the second mating surface are perpendicular to the floor.

[0018] In an embodiment, the first structural member and the second structural member each include a CLT panel, and the first structural member is a portion of a ceiling or floor and the second structural member is a portion of a wall.

[0019] In an embodiment, the first structural member includes a CLT panel, and the second structural member includes a column or beam.

[0020] In an embodiment, the first structural member and the second structural member each include a CLT panel. The CLT panel includes panel edges and panel faces. The first mating surface of the first structural member is along a panel edge and the second mating surface of the second structural member is along a panel face.

[0021] In an embodiment, the first structural member and the second structural member each include a CLT panel. The CLT panel includes panel edges and panel faces. The first mating surface of the first structural member is along a first panel face and the second mating surface of the second structural member is along a second panel face.

[0022] In another aspect of the present disclosure, a mass timber (MT) panel connector is provided that includes: a first bearing portion configured to affix to a first MT structural member, a second bearing portion configured to affix to a second MT structural member, and a fuse portion extending between the second bearing portion and the first bearing portion. The first bearing portion extending from a first end towards a second end. The second bearing portion extending from the second end towards the first end. The fuse portion is configured to plastically yield when an overload is transferred between the first bearing portion and the second bearing portion.

[0023] In an embodiment, the fuse portion includes a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion. The fuse portion includes a cross-sectional area that varies between the first tapering portion and the second tapering portion. The cross-sectional area reduces as it extends from the first bearing portion to the mid-fuse portion and increases as it extends from the mid-fuse portion to the second bearing portion. The cross-sectional area is smallest at the mid-fuse portion.

[0024] In an embodiment, a diametrical ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 2 / 3.

[0025] In an embodiment, a width ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 1 / 2.

[0026] In an embodiment, the first bearing portion and second bearing portion include cylindrical surfaces, and the first tapering portion and second tapering portion include cylindrical-conical shapes.

[0027] In an embodiment, the first bearing portion and second bearing portion include rectangular surfaces, and the first tapering portion and second tapering portion include trapezoidal prism shapes.

[0028] In an embodiment, the first bearing portion and second bearing portion include elliptical surfaces, and the first tapering portion and second tapering portion include elliptical-conical shapes.

[0029] In an embodiment, the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.BRIEF DESCRIPTION OF DRAWINGS

[0030] For a better understanding of at least certain embodiments, reference will be made to the following Detailed Description, which is to be read in conjunction with the accompanying drawings.

[0031] FIGS. 1A and 1B illustrates a perspective view and cross-sectional front-view, respectively, of an example general mass timber (MT) panel connector when in a normal (unstressed) state, according to an embodiment.

[0032] FIG. 1C illustrates a cross-sectional front-view of an example general MT panel connector when in an overloaded state, according to an embodiment.

[0033] FIG. 2 illustrates a diagram of an example MT structural member with connection holes for MT panel connectors, according to an embodiment. embodiments.

[0034] FIG. 3 illustrates a diagram of various sizes of connection holes in an edge of example MT structural member, according to an embodiment.

[0035] FIG. 4 illustrates a MT panel connector similar to the MT panel connector of FIGS. 1A-1C, except with bearing portions formed by sleeves, according to an embodiment.

[0036] FIG. 5 illustrates a diagram of an example MT panel connector including bearing portions having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment.

[0037] FIG. 6 illustrates a diagram of an example MT panel connector including bearing portions as sleeves having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment.

[0038] FIG. 7 illustrates a diagram of an example MT panel connector including bearing portions having a cylindrical shape and an elliptical cross-section and tapering portions having a elliptical-conical shape and elliptical cross-section, according to an embodiment.

[0039] FIGS. 8A and 8B illustrates front and side views of the MT panel connector, respectively, according to an embodiment.

[0040] FIG. 8C illustrates a side view of the MT panel connector when plastically yielding due to overload, according to an embodiment.

[0041] FIG. 8D illustrates a perspective view of the MT panel connector 800, according to an embodiment.

[0042] FIG. 9A illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly, according to an embodiment.

[0043] FIG. 9B illustrates a diagram of the MT structural members connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly, as shown in FIG. 9A, during an overload condition causing wall deformation, according to an embodiment.

[0044] FIG. 9C illustrates a diagram of four MT structural members that are connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly during an overload condition, according to an embodiment.

[0045] FIG. 10 illustrates a diagram of MT panel connectors connecting MT structural members in an edge-to-edge connection of an MT construction assembly to form a shear wall, according to an embodiment.

[0046] FIG. 11 illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly to form a wall having a horizontal joint, according to an embodiment.

[0047] FIG. 12 illustrates a diagram of MT panel connectors connecting MT structural members in a face-to-face connection of an MT construction assembly to form built-up shearwall boundary zones, according to an embodiment.

[0048] FIG. 13 illustrates a diagram of an example MT panel connector connecting MT structural members in a face-to-edge connection of an MT construction assembly, according to an embodiment.

[0049] FIG. 14 illustrates a diagram of an MT panel connector connecting MT structural members in a corner connection of an MT construction assembly, according to an embodiment.

[0050] FIG. 15 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment.

[0051] FIG. 16 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment.

[0052] FIG. 17 illustrates a flow chart for a method 1700 for designing MT panel connectors, according to an embodiment.

[0053] FIG. 18 illustrates a cross-sectional front-view of an example round MT panel connector 1800, according to an embodiment.

[0054] FIG. 19 illustrates a front-view of an example CLT panel 1900 with connection holes 1901 (or inputs) configured for use with the MT panel connector 1800 of FIG. 18, according to an embodiment.

[0055] FIG. 20 illustrates a cross-sectional front-view of an example rectangular MT panel connector 2000, according to an embodiment.

[0056] FIG. 21 illustrates a front-view of an example CLT panel 2100 with connection holes 2101 configured for use with the MT panel connector 2000 of FIG. 20, according to an embodiment.

[0057] The figures depict various embodiments of the present invention for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods depicted in the figures may be employed without departing from the principles of the invention described herein.DETAILED DESCRIPTION

[0058] Before the present invention is described in great detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0059] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0060] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

[0061] It is noted that, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements or use of a "negative" limitation.

[0062] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and depicted herein has discrete components and features which can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0063] During construction of buildings, mass timber (MT) structural members, such as cross-laminated timber (CLT) planks, are connected to other structural members of the building. This is conventionally done using steel plates that connect, for example, two planks using dowel connectors such as large numbers of bolts or screws. As stated above, these relatively small fasteners are often the weakest link in typical assemblies and do not develop the strength of the connected member.

[0064] In one aspect, a MT panel connector is provided that can be used to connect (or adjoin) MT structural members, such as CLT planks. The MT panel connectors can be inserted into large connection holes prepared in each of the two mating structural members. The connection holes can be shaped precisely to fit the MT panel connector such that the MT panel connector would fit snuggly in each structural member. A series of such MT panel connectors can form the connection between two structural members. The structural members can be joined in the field with the aid of mallets or other hammering devices. The MT panel connectors can be provided with beveled (or tapered) ends and holes to facilitate assembly, fit, and alignment. The MT panel connectors can be formed of many different cross-sectional shapes (e.g. round, rectangular, or elliptical) or of various types of materials (e.g. cold-formed or hot-rolled steel, aluminum, lead, shape memory alloy, wood, composite, or viscoelastic material). The MT panel connector is configured to be inserted within connection holes cored (or drilled) into two structural members, such as planks, boards, ceiling and flooring, walls, beams, etc., in order to connect (or adjoin) the two structural members together. The MT panel connector can connect two structural members together by being partially inserted into a connection hole of one structural member and partially inserted into a corresponding connection hole of the other structural member. The connection holes can be cored within an edge or face of the structural members. When the structural members are connected via the MT panel connector, the mating surfaces (i.e., the edge or face with the connection hole) of the structural members are adjoined with the MT panel connector disposed between and inside the structural members.

[0065] In an embodiment, at least one of the structural members is a MT structural member, and can include a CLT structural member, including CLT planks, panels, boards, walls, beams, etc. In an embodiment, the MT panel connector connects two MT structural members together by being partially inserted into a connection hole of one MT structural member and partially inserted into a corresponding connection hole of the other MT structural member. In an embodiment, the MT panel connector is configured to connect a MT structural member to another structural member that is a non-wood structural member, such as a steel beam for instance.

[0066] The connection holes can be cored into structural members to enable connections between various types of structural members and in various configurations or designs. Example types of structural members can include, for example, panels, planks, walls, beams, etc. The connection holes can be cored into the mating surfaces (e.g., faces or edges) and at varying locations on the structural member, depending on the application, function, or desired use. The connection holes can be pre-cored at predetermined locations during manufacturing, or alternatively can be subsequently cored at locations as desired before use. The structural members can be made of wood or some other suitable material, such as metals, metal alloys, polymeric materials, etc., or combination thereof.

[0067] In one embodiment, the MT panel connectors can connect CLT panels to one another, such as edge-to-edge, to create larger wall or floor assemblies for building. The MT panel connectors cam provide various benefits, such as eliminating the need for screw fasteners, which have limited strength and ductility and are costly and time consuming to install. In an embodiment, the MT panel connector is made of cast steel to facilitate mass production, control material characteristics, and ensure quality manufacture. In an embodiment, the MT panel connectors can include tapered ends to facilitate installation and provide tight-fit in the MT structural members. The fuse portion (or narrow, neck portion) of the MT panel connector is shaped to yield in a ductile and controlled manner, acting as a fuse when overloaded. This characteristic makes it well suited for incorporating into emergent MT seismic resisting walls as connection elements.

[0068] The MT panel connector is an elongated member having a bearing portion at each end of the elongated member with a fuse portion between the bearing portions. The bearing portions are configured to be inserted into the connection holes cored into the structural members and contact the wall of the connection hole. In this way, the bearing portions affix to the MT structural members. An MT structural member can be connected to another structural member (e.g., MT structural member or non-wood structural member) by inserting one bearing portion into a hole cored into the MT structural member and the other bearing portion into a hole cored into the other structural member. The MT panel connector enables the structural members to be connected so that the mating surfaces are adjoined with the MT panel connectors completely disposed within the structural members. In this way, the MT panel connector is similar to a dowel. In contrast, however, the MT panel connector includes the fuse portion disposed between the two mating members. The fuse portion has a smaller width (e.g., diameter) of than the bearing portions and thus forms a free movement volume (or space) within the connection hole that allows the fuse portion to deflect during overload condition. The fuse portion can be designed and formed by any suitable technique, such as milling the MT panel connector, formation via a mold, etc. The MT panel connector member can be made from any suitable material, such as cold-formed or hot-rolled steel, aluminum, lead, shape memory alloy, wood, composite, viscoelastic materials, metals, metal alloys, polymeric materials, etc., or combination thereof. In an embodiment, the MT panel connector is made entirely of cast steel. In another embodiment, the MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

[0069] The bearing portions can vary in shape in different embodiment, such as having a general shape of a cylinder, cuboid, or other suitable geometric or non-geometric shape. For example, in an embodiment, the bearing portion has a cylindrical shape with a cylindrical surface and a circular cross-section. In another embodiment, the bearing portion has a cylindrical shape with a cylindrical surface and an elliptical cross-section. In another embodiment, the bearing portion has a cuboid shape with rectangular surfaces and a rectangular cross-section. In another embodiment, the bearing portion has a cube shape with square surfaces and a square cross-section. The bearing portions can also include a tapered (or beveled) end to assist with insertion into the connection holes. In an embodiment, a bearing portion can include a sleeve that fits over an end of the MT panel connector to form the bearing portion that contacts the bearing surface of the connection hole. The sleeve can be coupled to the MT panel connector to become part of the MT panel connector. For example the sleeve can be sized and shaped to form fit and mechanically couple via frictional fit, or alternatively affixed through any suitable method, such as adhesive, mechanical connection (bolted, screwed, latched, etc.), etc. In an embodiment, one or more bearing surfaces can be formed from a sleeve affixed within a connection hole of a structural member formed from CLT. In an embodiment, one or more first bearing surfaces is bonded to the bearing surface of the connection hole. In an embodiment, one or more bearing surfaces can be press-fit with the bearing surface of the connection hole.

[0070] The width of the bearing portion (or bearing width) can vary depending on various factors, such as size, weight, or density of the structural members, expected load forces or overload conditions, the number of connection holes implemented, etc. Example bearing widths may include, but are not limited to, widths between 0.5 inch and 1 foot, such as between 1 inch and 6 inches, including embodiments with typical widths between 2 inches to 4 inches.

[0071] The fuse portion is positioned in the middle of the MT panel connector between the two bearing portions. The fuse portion has a smaller width and / or diameter (e.g., of the cross-section) than the bearing portions. In an embodiment, the fuse portion decreases generally in width and / or diameter from the bearing portions to a mid-fuse portion (or a middle point between the two bearing portions). In an embodiment, the mid-fuse portion can be halfway between the bearing surfaces in one implementation. In another implementation, the mid-fuse portion can be at another location in between (or in middle of) the bearing surfaces but not necessarily half-way.

[0072] The fuse portion can include a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion. The fuse portion can include a cross-sectional area that varies between the first tapering portion and the second tapering portion, with the cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion. The cross-sectional area is smallest at the mid-fuse portion.

[0073] In some implementations, setting the ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g. bearing portion width) to 2 / 3 can provide peak flexural stress at end of the free movement volume, but eases the stress gradient to increase the length of free movement volume that may yield in the event of overload. This is beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment, a diametrical ratio of the mid-fuse portion to the first bearing portion or the second bearing portion is 2 / 3.

[0074] Because the width (e.g., diameter) of the fuse portion is smaller than the bearing portions, the bearing portions contact adjacent surfaces of the connection holes (also referred to herein as bearing surfaces) while the fuse portion does not contact adjacent surfaces of the connection holes (also referred to herein as non-bearing surfaces). A free movement volume is formed by the space existing between the fuse portion and the non-bearing surfaces. The free movement volume enables the fuse portion to move or flex under overload conditions. In an embodiment, the fuse portion decreases in width (e.g., diameter) from the bearing surfaces to the mid-fuse portion, such as tapering from the bearing portions to the mid-fuse portion. For example, in an embodiment, the first and second bearing portions can include cylindrical surfaces, while first and second tapering portions of the mid-fuse portion can include cylindrical-conical shapes. In another embodiment, the first and second bearing portions can include rectangular surfaces, and the first and second tapering portions include trapezoidal prism shapes. In another embodiment, the first and second bearing portions include elliptical surfaces, and the first and second tapering portions include elliptical-conical shapes.

[0075] The MT panel connectors can provide significant benefits when the structural members are subjected to overload conditions. When the overload is transferred to the MT panel connectors, the MT panel connectors can plastically yield (or flex) within the connection holes in the structural members -- functioning similar to a hinge. The bearing portions remain affixed to the bearing surfaces of the connection hole. Because the fuse portion is adjacent to but not contacting the non-bearing surfaces, the fuse portion can flex during the overload condition. As a result, the structural members that are connected together via the MT panel connectors are able to slide relative to each other under the overload condition. With this in mind, the MT panel connectors can be configured or designed to promote stable, predictable load resistance through a broad range of deflection across the connection.

[0076] The maximum bearing stress in the MT panel connector would occur at the extreme ends of each bearing portion and vary linearly in between. In designing the MT panel connectors, it can be desirable to sufficiently limit this stress to avoid damaging (deforming) the MT panel connector and instead concentrate deformation in free movement volume (or zone) of the MT panel connectors. Internally, the MT panel connectors can experience peak flexural moment at the extreme ends of the free movement volume and vary linearly in between. If the cross section were kept constant through the free movement volume, the flexural stress would follow the same pattern; tapering the MT panel connectors in the free movement volume could be used to dictate within limits the length and location of the zone of peak stress. In an overload condition, ductile (yielding) materials such as metals would undergo plastic rotation concentrated at the locations of peak flexural stress, which would be associated with markedly increased deformation across the connection and energy dissipation.

[0077] The MT panel connectors and corresponding MT construction assemblies can provide significant beneficial features, including: predictable stable load deflection mechanism; concentration of deformation in the MT panel connectors, avoiding damage to wood; fewer parts requiring less labor; better control over the quality of the connection because fewer connectors need to be installed by hand; MT panel connectors are hidden so that connections will have cleaner more seamless aesthetic possibilities; simple, reliable installation method self-aligns connected members; adaptable to multiple materials and manufacturing techniques; etc.

[0078] The MT panel connector can be made from a variety of suitable methods, such as by milling techniques, molding techniques, turning techniques (e.g., lathe work), 3-D printing, etc., or combination thereof. Milling techniques may include, for instance, computer numerical control (CNC) milling, traditional milling, end milling, etc. Molding techniques may include, for instance, injection molding, casting, silicone or 3D-printed molds, etc. Lathe work may include, for instance, live tooling on CNC lathes or a hybrid machine that mills and turns. In one embodiment, the MT panel connector can be made by first creating a general connector using one of the above-mentioned techniques and thereafter removing material in the middle of the connector using one of the above-mentioned techniques to form the tapering portions. Applications of the MT panel connectors with a fuse portion are practically unlimited wherever shear force transfer between structural members, such as CLT planks, is desired. Some example connections can include, but are not limited to: edge to edge connections (e.g. built-up walls), edge to face connections (e.g. plank hung from wall panel), plank to steel beam connection (e.g. composite beam), etc. In one embodiment, the MT panel connector is specifically used as a CLT panel connector that connects a CLT structural member, including CLT planks, panels, boards, walls, beams, etc., to another structural member.

[0079] FIGS. 1A and 1B illustrate a perspective view and a cross-sectional front-view, respectively, of an example general MT panel connector when in a normal (unstressed) state, according to an embodiment. FIG. 1C illustrates a cross-sectional front view of an example general MT panel connector when in an overloaded state, according to an embodiment. FIGS. 1A-1C are described together and features and functions described for one figure may also be applicable to the other figures. For the sake of clarity and brevity, not all common features and functions are repeated for each figure. It should be appreciated that various features and functions described may be applicable to each of the examples shown in FIGS. 1A-1C. In FIG. 1A, a MT panel connector 100 is shown as an elongated member including: bearing portions 101, 102 at respective first and second ends 111, 112 of the MT panel connector 100, and a fuse portion 103 extending between the two bearing portions 101, 102 from the bearing portion101 to the bearing portion 102.

[0080] To facilitate understanding, the MT panel connector 100 is shown connecting a MT structural member 104 to another structural member 105, which can be a MT structural member or a non-wood structural member. The bearing portion 101 is shown inserted within a connection hole 106 cored into a mating surface 108 of the MT structural member 104. The bearing portion 102 is shown inserted within a connection hole 107 cored into a mating surface 109 the structural member 105. The bearing portions 101, 102 and the fuse portion 103 are completely disposed within the connection holes 106, 107 when the mating surfaces 108, 109 are abutting (or flush) with one another along a mating line 110. The bearing portions 101, 102 are shown including optional bevels 120, 121 at the ends 111, 112, respectively, which can assist with insertion of the bearing portions 101, 102 into the connection holes 106, 107 or other connections holes.

[0081] The fuse portion 103 includes tapering portions 113, 114 and a mid-fuse portion 115. The tapering portions 113, 114 extend from respective bearing portions 101, 102 to the mid-fuse portion 115 connecting the tapering portions 113, 114. The tapering portions 113, 114 decrease in cross-sectional area from the respective bearing portions 101, 102 to the mid-fuse portion 115. In an embodiment, the fuse portion 103 has the smallest cross-sectional area at the mid-fuse portion 115.

[0082] When the MT structural member 104 and the structural member 105 are connected by the MT panel connector, the mating surfaces 108, 109 are abutting with the two connection holes 106, 107 aligned creating a cavity where the MT panel connector 100 is completely disposed within. The connection holes 106, 107 include bearing surfaces 116, 117 and non-bearing surfaces 118, 119, respectively. The bearing surfaces 116, 117 are the surfaces within the respective connection holes 106, 107 that contact the bearing portions 101, 102 of the MT panel connector 100 when inserted. The non-bearing surfaces 118, 119 are positioned between the bearing portions 101, 102 and the mating surfaces 108, 109. Because the tapering portions 113, 114 decrease in cross-sectional area from the respective bearing portions 101, 102, the non-bearing surfaces 118, 119 do no contact the tapering portions 113, 114 and a free-movement volume 120 is formed. The free-movement volume 120 is defined by the space (or gap) formed between the tapering portions 113, 114 and the respective non-surface bearing surfaces 118, 119.

[0083] As described above, MT panel connectors are configured to be inserted into connection holes cored into MT structural members to connect MT structural members to other structural members, which may be MT or non-wood structural members. Non-wood structural members can include materials made of metals, metal alloys, polymeric materials, etc. The structural members can include various sized and shaped members but should provide a mating surface for the connection holes and sufficient depth to core a connection hole. Example structural members may include, but are not limited to various panels, planks, boards, ceiling and flooring, walls, beams, etc.

[0084] FIG. 2 illustrates a partially exploded diagram of an example MT structural member with connection holes for MT (e.g., CLT) panel connectors, according to an embodiment. In FIG. 2, the MT structural member 200 is shown as a CLT structural member and having layers 201 of slender wood elements, where the slender elements in each layer are perpendicular to the adjacent layers. The MT structural member is described here specifically as a CLT structural member (e.g. CLT panel) for exemplary purposes and is not intended to be limiting. It should be appreciated that other MT structural members that are not CLT may also be applicable without compromising the underlying principles of the MT panel connectors described herein. The MT structural member 200 is shown as a partially assembled 4-ply, 4-layer panel having two faces 202 and four edges 203. In the example MT structural member 200 shown, the faces 202 refer to the two large faces on top and bottom of the panel, and the four edges 203 refer to the faces on the edges (or sides) of the panel.

[0085] It should be appreciated that the MT structural member 200 is not limited to four layers as shown in FIG. 2 and may include any suitable number of layers and ply. For example, a MT structural member can have three ply and three layers; seven ply and seven layers; nine ply and nine layers; seven ply and five layers 201E; nine ply and seven layers; or any other number of ply and layers.

[0086] The MT structural member 200 is shown having connection holes 204, 205 cored in the faces 202, 203, respectively. It is noted that the connection hole will be present on the mating surface of the fourth layer when fully assembled. The connection holes shown in FIG. 2 are example connection holes and are not intended to be limiting. The connection holes can vary in location, shape, size, number, etc., in different embodiments. The connection holes can be cored into any suitable mating surface, including faces and edges. Therefore, when referring to the connection hole within a mating surface of a MT structural member, it should be appreciated that the mating surface can be a face or edge, unless explicitly stated as limited otherwise.

[0087] FIG. 3 illustrates a diagram of various sizes of connection holes in an edge of example MT structural member, according to an embodiment. In FIG. 3, an edge 303 is shown for a MT structural member 300 having seven ply and seven layers 301. Various sized connection holes 304, 305, 306, 307 are shown cored into the mating surface (or edge in this example) 303 of the MT structural member 300. The size of the connection holes can vary in different embodiments as needed for design specification, and may be based on, for instance, the number of ply or layers, the configuration of the ply and layers, the location of the connection holes, the structural members being connector, the materials of the structural members being connected, the expected function, load, strain, etc. of the structural members being connected, the number of connection holes being implemented, etc. For example, the diameter of the connection hole can be a factor when calculating the available dowel bearing stress perpendicular to the grain, and further, may be weighted as a function of ply thickness and MT panel connector diameter. Generally speaking, example width ranges of connection holes that may be typically used in common construction of buildings may include, but are not limited to, widths between 0.5 inch and 1 foot, such as between 1 inch and 6 inches, including embodiments with typical widths between 2 inches to 4 inches.

[0088] When under stress, such as the MT panel connector 100 encountering force (e.g., load or stress) in an overload condition, the fuse portion 103 and the free-movement volume 120 can limit the force applied to the structural members and reliably control the response of the connection under overload. FIG. 1C illustrates a diagram of the MT panel connector 100 of FIGS. 1A,1B when overloaded, according to an embodiment. In FIG. 1C, the MT structural members 104, 105 are overloaded and moved (or slid) relative to one another. When the overload is transferred between the bearing portions 101, 102, the tapering portions 113, 114 and the free-movement volume 120 enable the fuse portion 103 to plastically yield (or flex) in the free-movement volume 120. The overload causes relative movement between the structural members 104, 105 such that the connection holes 106, 107 can become unaligned. However, because the fuse portion 103 can plastically yield in the free movement volume 120, the bearing portions 101, 102 do not dislodge from (or remain lodged to) the bearing surfaces 116, 117, respectively, when the connection holes 106, 107 become unaligned from the overload. In particular, plastic yielding of the fuse portion 103 can occur at the ends of the free-movement volume 120 where the tapering portions 113 ,114 meet the respective bearing portions 101, 102, functioning similar to a hinge at each location H1,H2 in FIGS. 1A-1C. In some instance, the overload may be sufficient to cause the MT structural members 104, 105 to move resulting in the tapering portions 113, 114 to contact the non-bearing surfaces 118, 119 of the MT structural members 104, 105, as shown in FIG. 1C at contact point CP. In the overload condition, the MT panel connector can deform in a plastic manner by yielding the connector in flexure. The amount of acceptable movement may be limited by: fracture of the MT panel connector, and the bearing of the MT panel connector against the wood in the free movement volume. In an embodiment, the connection hole can be beveled in the wood to increase acceptable deflection.

[0089] Depending on the material implemented and other design factors, the fuse portion can be designed to exhibit different characteristics. Dimensions of the MT panel connector (e.g., the size, width, and shape of the bearing portions, the fuse portion, and the free-movement volume) and can be derived to promote stable, predictable load resistance through a broad range of deflection across the connection. In an embodiment, the ratio of the diameter of the mid-fuse portion 115 to one or both of the diameters of the bearing portions 101, 102 can be set as 2 / 3, or approximately 2 / 3, such as within a tolerance range of 10% or less, including a tolerance range of 5% or less.

[0090] In an embodiment, a MT panel connector can include a sleeve on one or both bearing portions. FIG. 4 illustrates a MT panel connector 400 similar to the MT panel connector 100 of FIGS. 1A-C, except with bearing portions 401, 402 formed by sleeves, according to an embodiment. For the sake of clarity and brevity, similar features and functions are not necessarily described here again but should be understood as still be applicable. The MT panel connector 400 includes bearing portions 401, 402 at respective first and second ends 411, 412 of the MT panel connector 400, and a fuse portion 403 extending between the two bearing portions 401, 402 from the bearing portion 401 to the bearing portion 402. The bearing portions 401, 402 are formed by sleeves S over a dowel (or rod) D. The sleeves S are at the ends 411, 412 of the MT panel connector 400. The sleeves, as the bearing portions 401, 402, contact the bearing surfaces of the connection holes (e.g., the bearing surfaces 116, 117 of the connection holes 106, 107) when the bearing portions 401, 402 are inserted in the connection holes of the two structural members having mating line 510. The fuse portion 103 includes tapering portions 413, 414 and a mid-fuse portion 415. The tapering portions 413, 414 extend from respective bearing portions 401, 402 to the mid-fuse portion 415 connecting the tapering portions 413, 414. The tapering portions 413 , 414 decrease in cross-sectional area from the respective bearing portions 401, 402 to the mid-fuse portion 415. In an embodiment, the fuse portion 403 has the smallest cross-sectional area at the mid-fuse portion 415. A length lb of the bearing portion (also referred to herein as “bearing length”) and a length lf of the free zone (also referred to herein as the “free length”) is shown in FIG. 4 and can be applicable to other MT panel connectors shown in the figures. A width db of the bearing portions 401, 402 is shown and can be applicable to other MT panel connectors. As the MT panel connector 400 includes sleeves S, a width dr is shown to indicate the width of the rod inside the sleeve (i.e., the MT panel connector alone -- without the sleeve).

[0091] It should be appreciated that the shape and size of the MT panel connector 100 and its components (e.g., the bearing portions, 101, 102, the fuse portion 103, the tapering portions 113, 114 of the fuse portion 113, etc.) are not limited to the shape and sizes shown in FIGS. 1A-1C, and can vary in different embodiments. For example, the bearing portions can have a general shape of a cylinder, cuboid, or other suitable geometric or non-geometric shape. In an embodiment, the bearing portions have a cylindrical shape and surface and a circular cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have a cylindrical-conical shape (e.g., a frustum of a cone) and circular cross-section.

[0092] FIG. 5 illustrates a diagram of an example MT panel connector 500 including bearing portions 501, 502 having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1A-C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 500 includes the bearing portions 501, 502 at respective first and second ends 511, 512 of the MT panel connector 500, and a fuse portion 503 extending between the two bearing portions 501, 502 from the bearing portion 501 to the bearing portion 502. The mating line 510 is shown for the two structural members being adjoined. As stated above, the bearing portions 501, 502 have a cylindrical shape and a circular cross-section. While the bearing portions 501, 502 are shown with bevels 520, 521 at their ends, the bevels 520, 521 may not be present in other embodiments. The circular cross-section of the bearing portions 501, 502 is shown with a width (or diameter) db in detail 5A of FIG. 5 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0093] The fuse portion 503 includes tapering portions 513, 514 and a mid-fuse portion 515. The tapering portions 513, 514 extend from respective bearing portions 501, 502 to the mid-fuse portion 515 connecting the tapering portions 513, 514. The tapering portions 513, 514 decrease in cross-sectional area from the respective bearing portions 501, 502 to the mid-fuse portion 515. In an embodiment, the fuse portion 503 has the smallest cross-sectional area at the mid-fuse portion 515. As stated above, the tapering portions 513, 514 have a cylindrical-conical shape and a circular cross-section, which are shown in respective details 5B and 5C of FIG. 5 for reference purposes. In detail 5B of FIG. 5, the truncated cylindrical shape of the tapering portion 514 is shown for reference purposes. The width (or diameter) dend of the larger end of the cylindrical-conical is shown along with the width (or diameter) dmf of the cylindrical-conical at the mid-fuse portion 515. In detail 5C of FIG. 5, the circular cross-section of the tapering portion 514 is shown for reference purposes and has a width (or diameter) dt that decreases from dend to dmf. Similar features apply to the tapering portion 513.

[0094] FIG. 6 illustrates a diagram of an example MT panel connector 600 including bearing portions 601, 602 as sleeves having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1, 4 , and 5 are not necessarily described here again but should be understood as still be applicable. The MT panel connector 600 includes sleeves as the bearing portions 601, 602 at respective first and second ends 611, 612 of the MT panel connector 600, and a fuse portion 603 extending between the two bearing portions 601, 602 from the bearing portion 601 to the bearing portion 602. The mating line 610 is shown for the two structural members being adjoined. As stated above, the bearing portions 601, 602 are sleeves having a cylindrical shape and a circular cross-section. While the bearing portions 601, 602 are shown with bevels 620, 621 at their ends, the bevels 620, 621 may not be present in other embodiments. The circular cross-section of the bearing portions 601, 602 is shown with a width (or diameter) db in detail 6A of FIG. 6 for reference purposes. Because the MT panel connector 600 include sleeves, the sleeves are also referenced as sleeves 601, 602 in FIG. 6, which also have widths db. The inner width dr represents the width or diameter within the sleeves 601, 602, or put another way, the width or diameter of the portion of the rod or dowel where the sleeves 601, 602 are coupled to. The mid-fuse portion has a width (or diameter) dmf. In other embodiments, the widths db and dr of the bearing portions 601 may differ from the widths db and dr of the bearing portions 602, respectively.

[0095] The fuse portion 603 includes tapering portions 613, 614 and a mid-fuse portion 615, which are similarly to that in FIG. 5 and thus not repeated here again for the sake of brevity. The tapering portions 613, 614 have a cylindrical-conical shape and a circular cross-section similar to those shown in respective details 6B and 6C of FIG. 5.

[0096] In another embodiment, the bearing portions have a cylindrical shape with an elliptical cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have an elliptical-conical shape (e.g., frustum of a cone having an elliptical) with an elliptical cross-section. FIG. 7 illustrates a diagram of an example MT panel connector 700 including bearing portions 701, 702 having a cylindrical shape and an elliptical cross-section and tapering portions having a elliptical-conical shape and elliptical cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1A-1C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 700 includes the bearing portions 701, 702 at respective first and second ends 711, 712 of the MT panel connector 700, and a fuse portion 703 extending between the two bearing portions 701, 702 from the bearing portion 701 to the bearing portion 702. The mating line 710 is shown for the two structural members being adjoined. As stated above, the bearing portions 701, 702 have a cylindrical shape and an elliptical cross-section. The bearing portions 701, 702 can optionally include bevels at their ends in other embodiments. The elliptical cross-section of the bearing portions 701, 702 is shown with a width db (e.g., shown as the major axis of the ellipse) in detail 7A of FIG. 7 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0097] The fuse portion 703 includes tapering portions 713, 714 and a mid-fuse portion 715. The tapering portions 713, 714 extend from respective bearing portions 701, 702 to the mid-fuse portion 715 connecting the tapering portions 713, 714. The tapering portions 713, 714 decrease in cross-sectional area from the respective bearing portions 701, 702 to the mid-fuse portion 715. In an embodiment, the fuse portion 703 has the smallest cross-sectional area at the mid-fuse portion 515. As stated above, the tapering portions 713, 714 have an elliptical-conical shape and an elliptical cross-section, which are shown in respective details 7B and 7C of FIG. 7 for reference purposes. In detail 7B of FIG. 7, the elliptical-conical shape of the tapering portion 714 is shown for reference purposes. The width dend of the larger end of the elliptical-conical shape is shown along with the width dmf of the cylindrical-conical at the mid-fuse portion 715. In detail 7C of FIG. 7, the elliptical cross-section of the tapering portion 714 is shown for reference purposes and has a width dt that decreases from dend to dmf. Similar features apply to the tapering portion 713.

[0098] In yet another embodiment, the bearing portion has a cuboid shape with a rectangular cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have a trapezoidal prism shape with a rectangular cross-section. FIGS. 8A, 8B, 8C and 8D illustrate diagrams of an example MT panel connector 800 including bearing portions 801, 802 having a cuboid shape and a rectangular cross-section and tapering portions having a trapezoidal prism shape and rectangular cross-section, according to an embodiment. FIGS. 8A and 8B illustrates front and side views of the MT panel connector 800, respectively, according to an embodiment. FIG. 8C illustrates a side view of the MT panel connector 800 when plastically yielding due to overload, according to an embodiment. FIG. 8D illustrates a perspective view of the MT panel connector 800, according to an embodiment. For the sake of clarity and brevity, FIGS. 8A-8D are described together, and similar features and functions to those shown in FIGS. 1A-1C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 800 includes the bearing portions 801, 802 at respective first and second ends 811, 812 of the MT panel connector 800, and a fuse portion 803 extending between the two bearing portions 801, 802 from the bearing portion 801 to the bearing portion 802. The mating line 810 is shown for the two structural members being adjoined. As stated above, the bearing portions 801, 802 have a cuboid shape and a rectangular cross-section. The bearing portions 801, 802 can optionally include bevels at their ends in other embodiments. The rectangular cross-section of the bearing portions 801, 802 is shown with a width db (shown as the major axis of the rectangle) in detail 8A of FIG. 8 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0099] The fuse portion 803 includes tapering portions 813, 814 and a mid-fuse portion 815. The tapering portions 813, 814 extend from respective bearing portions 801, 802 to the mid-fuse portion 815 connecting the tapering portions 813, 814. The tapering portions 813, 814 decrease in cross-sectional area from the respective bearing portions 801, 802 to the mid-fuse portion 815. In an embodiment, the fuse portion 803 has the smallest cross-sectional area at the mid-fuse portion 815. As stated above, the tapering portions 813 ,814 have a trapezoidal prism shape and an rectangular cross-section, which are shown in respective details 8B and 8C of FIG. 8 for reference purposes. In detail 8B of FIG. 8, the trapezoidal prism shape of the tapering portion 814 is shown for reference purposes. The width dend (shown as the major axis of the rectangle) of the larger end of the trapezoidal prism is shown along with the width dmf of the trapezoidal prism at the mid-fuse portion 815. In detail 8C of FIG. 8, the rectangular cross-section of the tapering portion 814 is shown for reference purposes and has a width dt that decreases from dend to dmf. Similar features apply to the tapering portion 713.

[0100] In the overload condition, the MT panel connector 800 can deform in a plastic manner by yielding the connector in flexure. By sufficiently beveling the connection hole in the wood, it can be enable the steel to fracture prior to the connector bearing against the wood, which may be desirable in certain applications.

[0101] Setting the ratio of tapered to full bearing portion width to 0.5 can ensure peak flexural stress at end of free movement volume, but eases the stress gradient to increase the length of free zone that may yield in the event of overload. This is beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment, a width ratio of the mid-fuse portion to the first bearing portion or second bearing portion is ½.

[0102] It should be appreciated that other embodiments are also possible, such as the bearing portion having a cube shape with square surfaces and a square cross-section. The tapering portions have a trapezoidal prism shape with a trapezoidal prism surface and rectangular cross- section. For the sake of clarity and brevity, not every variation is shown in a figure and described.

[0103] In use, the MT panel connectors are inserted within holes that are cored into MT structural members. The MT structural members can include, for example, panels, planks, walls, beams, etc., with connection holes drilled into its faces and / or edges, depending on the application, function, or desired use. The MT structural members can be manufactured with the connection holes pre-cored at predetermined locations, or alternatively can be subsequently drilled at various locations as desired. The MT structural members can be wood or some other material, such as metals, metal alloys, polymeric materials, etc., or combination thereof.

[0104] When two MT structural members are selected for connection, with the corresponding connection drilled into appropriate locations, an MT panel connectors can be inserted into one or more connection holes in one of the MT structural members (e.g., wood structural member) and then the exposed portions of the MT panel connectors can then be inserted into the corresponding connection holes in the other MT structural member (e.g., wood or non-wood structural member) until the mating surfaces are abutting. In some instance, force may be applied to one or both of the MT structural members to drive the MT panel connectors completely into the connection holes so that the mating surfaces abut. Hammers or other hammering tools may also be used to assist with the completely adjoining the structural members via the MT panel connectors. This process can be repeated for additional connections between either of the two MT structural members and other MT structural members as desired.

[0105] Applications of the MT panel connectors with a fuse portion are practically unlimited wherever shear force transfer between structural members, such as CLT planks, is desired. Some example connections can include: edge to edge connections (e.g. built-up walls); edge to face connections (e.g. plank hung from wall panel); plank to steel beam connections (e.g. composite beam). It should be appreciated that parallel attachments also can be implemented to transfer moment demands between panels.

[0106] FIGS. 9-16 are provided below and describe various example MT construction assemblies (e.g., CLT construction assemblies) including structural members connected via MT panel connectors. It should be appreciated that the previous discussion for FIGS. 1-8 may also be applicable for FIGS. 9-16 and not every common feature or variation is repeated here again for the sake of clarity and brevity. It should also be appreciated that while the example MT construction assemblies may include structural members or MT structural members that are adjoined to form a portion of a framed structure, the description may also be applicable to MT construction assemblies for other structural members than shown. The examples shown are for explanatory purposes and are not intended to be limiting. One example MT construction assembly includes various types and configurations of stacked panel walls (e.g., panel shear walls). Such MT construction assemblies MT and MT panel connectors use can provide many advantages, such as being self aligning, enable simple fit and installation, result in no exposed fasteners, enable strong shear connections, being suitable and practical for frame buildings, applicable to wall and floor assemblies, provide for a compact and efficient shear wall assembly, enable rapid installation, customizable to vary in size, strength, and shape based on panel thickness, etc.

[0107] FIG. 9A illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly, according to an embodiment. In FIG. 9A, MT panel connectors 900 are shown connecting MT structural member 904 with MT structural member 905 to form a portion of a framed structure – e.g., a wall connected with a vertical joint at the edges of the MT structural members. The mating line 910 is shown between structural members 904 and 905. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0108] FIG. 9B illustrates a diagram of the MT structural members 904, 905 connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly, as shown in FIG. 9A, during an overload condition causing wall deformation. When the MT structural members 904 and 905 undergo stress or force it can cause an overload condition which transfers force to the MT panel connector 900. In the overload condition, the fuse portion 103 and the free-movement volume 120 of the MT panel connectors 900 can limit the force in the MT panel connector 900 and the MT structural members 904 and 905 to reliably control the response of the connection under overload. The MT structural members 904 and 905 are overloaded and moved (or slid) relative to one another. As previously described for FIG. 1C and referred to here again for FIG. 9B, when the overload is transferred between the bearing portions 101, 102 of the MT panel connectors 900, the tapering portions 113, 114 and the free-movement volume 120 enable the fuse portion 103 to plastically yield (or flex) in the free-movement volume 120. The overload causes relative movement between the MT structural members 904 and 905 such that the connection holes 106, 107 can become unaligned. However, because the fuse portion 103 can plastically yield in the free movement volume 120, the bearing portions 101, 102 remain lodged to the bearing surfaces 116, 117, respectively. In particular, plastic yielding of the fuse portion 103 of the MT panel connectors 900 can occur at the ends of the free-movement volume 120 where the tapering portions 113, 114 meet the respective bearing portions 101, 102, functioning similar to a hinge at each location H1,H2. This enables the wall to deform when overloaded.

[0109] FIG. 9C illustrates a diagram of four MT structural members 904, 905, 906, 907 that are connected with MT panel connectors 900 in an edge-to-edge connection of an MT construction assembly during an overload condition, according to an embodiment. .In FIG. 9C, MT panel connectors 900 are shown connecting the MT structural member 904 with the MT structural member 905, the MT structural member 905 with MT structural member 906, and the MT structural member 906 with MT structural member 907 to form a portion of a framed structure – e.g., a wall connected with a vertical joint at the edges of the MT structural members. The overload causes wall deformation between the adjacently connected MT structural members connected via MT panel connectors, as similarly described for FIG. 9B. This is not limited to 2 or 4 panels as shown, but can be applicable to any number of panels connected via the MT panel connectors.

[0110] In design to resistance to seismic demands, ductility is an important property of the Lateral Force Resisting System (LFRS). Ductility is the ability for a member to deform in a plastic manner without loss of stress. This property dampens the movement of a structure during an earthquake, effectively limiting lateral displacement and promoting stability. The amount of ductility desired generally correlates with the intensity of seismic demands expected at a given site. In certain aspects, steel MT panel connectors are configured to yield in a ductile manner, precluding nonductile bearing and crushing of the wood. In a CLT wall system, for instance, planks may be joined together to form larger walls capable of resisting earthquake demands. In certain applications, better seismic performance can be accomplished through joining panels along vertical seams between muti-story CLT planks instead of joining panels along horizontal seams. For instance, slender panels may dissipate energy along the vertical seams and rock back into place when the earthquake, and the amount of ductility desired is achievable simply by specifying the number of vertical seams (horizontal seams offer ductility limited to a single seam). As shown in FIGS. 9B and 9C, the system ductility varies linearly with one-half the number of sub-panels.

[0111] FIG. 10 illustrates a diagram of MT panel connectors connecting MT structural members in an edge-to-edge connection of an MT construction assembly to form a portion of a framed structure – e.g., a shear wall, according to an embodiment. For example, in FIG. 10, MT panel connectors 1000 are shown inserted within MT structural member 1004 and used for connection to MT structural members 1005A and 1005B. In FIG. 10, the MT structural member 1004 is already connected to the MT structural member 1005B, with the MT panel connectors 1000 fully inserted within the connection holes of the mating surface of the MT structural member 1004 and the edge of the MT structural member 1005B. Some of the MT panel connectors 1000 are shown already inserted into and exposed from (or protruding from) the mating surface of the MT structural member 1004. The exposed MT panel connectors 1000 can then be inserted within connection holes on the edge of the to the MT structural member 1005A to connect the MT structural members 1004 and 1005A. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0112] FIG. 11 illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly to form a portion of a framed structure – e.g., a wall having a horizontal joint, according to an embodiment. In FIG. 11, MT panel connectors 1100 are shown connecting MT structural member 1104 with MT structural member 1105 to form a wall having a vertical joint at the edges of the MT structural members. The mating line 110 is shown for the two structural members 1105, 1105 being adjoined. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT planks for instance. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces parallel to the floor.

[0113] FIG. 12 illustrates a diagram of MT panel connectors connecting MT structural members in a face-to-face connection of an MT construction assembly to form a portion of a framed structure – e.g., built-up shearwall boundary zones, according to an embodiment. For example, in FIG. 12, MT panel connectors 1200 are shown inserted within MT structural member 1204 and used for connection to MT structural members 1205A, 1205B, 1205C, and 1205D. Some of the MT panel connectors 1200 are connecting the MT structural members 1204 and 1205A through connections holes in their corresponding mating surfaces. Further, some of the MT panel connectors 1200 are connecting the MT structural members 1204 and 1205B through connections holes in their corresponding mating surfaces. This is similarly done with the MT structural members 1204 and 1205C, as well as MT structural members 1204 and 1205D, through connections holes in their corresponding mating surfaces. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT planks for instance. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0114] FIG. 13 illustrates a diagram of an example MT panel connector connecting MT structural members in a face-to-edge connection of an MT construction assembly, according to an embodiment. For example, in FIG. 13, an MT panel connector 1300 is shown inserted within, and connecting, a MT structural member 1304 (e.g., a CLT wall plank) and a MT structural member 1305 (e.g., a CLT floor plank) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, and the first CLT structural member is a portion of a ceiling or floor and the second CLT structural member is a portion of a wall.

[0115] FIG. 14 illustrates a diagram of an MT panel connector connecting MT structural members in a corner connection of an MT construction assembly, according to an embodiment. For example, in FIG. 14, an MT panel connector 1400 is shown inserted within, and connecting, a MT structural member 1404 (e.g., a CLT wall plank) and a MT structural member 1405 (e.g., a CLT floor plank) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, and the first CLT structural member is a portion of a ceiling or floor and the second CLT structural member is a portion of a wall.

[0116] FIG. 15 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment. For example, in FIG. 15, an MT panel connector 1500 is shown inserted within, and connecting, a MT structural member 1504 (e.g., a CLT floor plank) and a MT structural member 1505 (e.g., a wood beam) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting a CLT structural member, such as a CLT panel, and a second structural member including a column or beam.

[0117] FIG. 16 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment. For example, in FIG. 16, an MT panel connector 1600 is shown inserted within, and connecting, a MT structural member 1604 (e.g., a CLT floor plank) and a structural member 1605 (e.g., a steel beam). One bearing surface 1606 of the MT panel connector 1600 is inserted within the connection hole of the MT structural member 1604. The other bearing surface 1607 is connected to the structural member 1605 and also disposed within the connection hole of the MT structural member 1604 to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting a CLT structural member, such as a CLT panel, and a second structural member including a column or beam. In one implementation where the structural member 1605 is made from steel, such as with a steel beam, the MT panel connector 1600 can be fabricated from standard structural steel material grades and welded to the steel member 1605.

[0118] In one aspect of the present disclosure, methods are provided for designing MT panel connectors, such as the MT panel connectors discussed herein and shown in the figures. FIG. 17 illustrates a flow chart for a method 1700 for designing MT panel connectors, according to an embodiment. FIG. 18 illustrates a cross-sectional front-view of an example round MT panel connector 1800, according to an embodiment. FIG. 19 illustrates a front-view of an example CLT panel 1900 with connection holes 1901 (or inputs) configured for use with the MT panel connector 1800 of FIG. 18, according to an embodiment. FIG. 20 illustrates a cross-sectional front-view of an example rectangular MT panel connector 2000, according to an embodiment. FIG. 21 illustrates a front-view of an example CLT panel 2100 with connection holes 2101 configured for use with the MT panel connector 2000 of FIG. 20, according to an embodiment. FIGS. 17 is described below in conjunction with the specific examples shown in FIGS. 18 and 19, as well as FIGS. 20 and 21.

[0119] In FIG. 18, the MT panel connector 1800 is shown in MT structural members 1804, 1805 and includes bearing portions 1801, 1802, mid-fuse portion 1803, and a mating line 1810. One of the sleeves (sleeve 1811) is also shown coupled to (or fit) over a dowel (or rod) portion D of the MT panel connector 1800. Also shown is a bevel hole 1812 and bevel 1821, which can be implemented in some embodiments to ease installation. The bearing portions 1801, 1802 are shown with a width db (equal to the width of the sleeve) and lengths lb (may also be referred to as the bearing length). The rod D is shown with a width dr. One of the tapered portions (tapered portion 1813) is shown with a length lf (may also be referred to herein as the free length). The tapered portion 1813 has a width dmf at the mating line 1810 (i.e., at the mid-fuse portion). It should be appreciated that not all features of the MT panel connector has been described here for the sake of clarity and brevity, however applicable features from other figures may equally apply here.

[0120] Similarly, in FIG. 20, the MT panel connector 2000 is shown in MT structural members 2004, 2005 and includes bearing portions 2001, 2002, mid-fuse portion 2003, and a mating line 2010. One of the sleeves (sleeve 2011) is also shown coupled to (or fit) over a dowel (or rod) portion D of the MT panel connector 2000. Also shown is a bevel hole 2012 and bevel 2021, which can be implemented in some embodiments to ease installation. The bearing portions 2001, 2002 are shown with a width db and lengths lb (also referred to as the bearing length). The rod is shown with a width dr. One of the tapered portions (tapered portion 2013) is shown with a length lf (also referred to as the free length). The tapered portion 1813 has a width dmf at the mating line 1810 (i.e., at the mid-fuse portion). It should be appreciated that not all features of the MT panel connector has been described here for the sake of clarity and brevity, however applicable features from other figures may equally apply here.

[0121] In FIG. 17, a method 1700 for designing a MT panel connector is shown, such as the MT panel connectors 1800 and 2000. At block 1705 of the method 1700, a target sheer strength per MT panel connector is determined. The target sheer strength depends on the properties of the CLT panel (e.g., CLT plank) and MT panel connector spacing S. Example CLT panels 1900 and 2100 are shown in FIGS. 19 and 21 along with associated MT panel connector spacings S between the connection holes 1901 and 2101, respectively. An available shear stress (Fv) of the CLT panel can be obtained from the CLT manufacturer’s specification. The target MT panel connector strength (Vtarg) can be calculated as the shear stress (Fv) multiplied by the MT panel connector spacing S and the CLT panel thickness (tCLT).

[0122] At block 1710, an MT panel connector material is selected and its associated flexural and shear yield stresses (Fy,r) and (Fv,r) are determined. At block 1715, specifications for the MT panel connector and the connection holes are selected. For example, in the example round MT panel connector 1800 for FIGS. 18 and 19, a bearing portion width db and rod width dr can be selected. The rod width dr can also be seen in in FIG. 6, and can be equivalent to dend shown in FIG. 5. In the example rectangular MT panel connector 2000 for FIGS. 20 and 21, a thickness (tr), bearing portion width (db), and free zone width (or width dr) can be selected.

[0123] At block 1720, a ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g., bearing portion width) is selected. In an embodiment for the round MT panel connector for FIGS. 18 and 19, setting the ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g. bearing portion width) to 2 / 3 can provide peak flexural stress at end of the free movement volume, but eases the stress gradient to increase the length of free movement volume that may yield in the event of overload. This can be beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment for the rectangular MT panel connector for FIGS. 20 and 21, setting the ratio of tapered width to full bearing portion width to 1 / 2 (or 0.5) can ensure peak flexural stress at end of free movement volume, but eases the stress gradient to increase the length of free zone that may yield in the event of overload. This can be beneficial from the standpoint of energy dissipation and forestalling fracture.

[0124] At block 1725, a reduction factor (ød) is selected that will limit usage of wood bearing stress and thereby ensure MT panel connector yielding precludes and prevents excessive bearing stress. In an embodiment, a factor of 2 / 3 is reasonable given steel strain hardening.

[0125] At block 1730, critical values lf and lb are determined. Without the benefit of a solver, combinations of the two critical dimensions lf and lb can be tried such that the following two conditions are met: 1. peak MT panel connector flexural stress (at edge of the free zone) equals MT panel connector yield stress Fy,r, and 2. MT panel connector shear force equals target shear force (constrained by shear strength of CLT panel): V=Vtarg. Note that if the MT panel connector diameter is too small, shear yield of the dowel can control the design, resulting in a shear capacity less than Vtarg, which may be a suboptimal use of the MT panel connector in some cases. With the help of a solver, the unique values of the two critical dimensions lf and lb (free length and bearing length, respectively) may be found with desired accuracy.

[0126] Example measurements for the free length lf and bearing length lb of the MT panel connectors may include, but are not limited to, values within the range from 0.2 inches to 6 inches for the free length lf; and values within the range from 2 inches to 10 inches for the bearing length lb. In an embodiment, the free length lf of the MT panel connector is a value within 0.4 inches and 4.2 inches, while the bearing length lb is a value within 4 inches and 8.25 inches.

[0127] It should be appreciated that other variations are contemplated and not every variation is provided as an example. For example, the first structural member and the second structural member can each include a CLT panel that includes panel edges and panel faces. In one implementation, the mating surface of the first structural member can be along a first panel face and the mating surface of the second structural member can along a second panel face. In another implementation, the mating surface of the first structural member can also be along a first panel edge and the mating surface of the second structural member can be along a second panel face.

[0128] Throughout the foregoing description, and for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the described techniques. It will be apparent, however, to one skilled in the art that these techniques can be practiced without some of these specific details. Although various embodiments that incorporate these teachings have been shown and described in detail, those skilled in the art could readily devise many other varied embodiments or mechanisms to incorporate these techniques. Also, embodiments can include various operations as set forth above, fewer operations, or more operations; or operations in an order. Accordingly, the scope and spirit of the invention should be judged in terms of the claims, which follow as well as the legal equivalents thereof.

Examples

Embodiment Construction

[0058]Before the present invention is described in great detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0059]Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated ran...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 761,981, filed February 23, 2025, the entirety of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] The subject matter of the present disclosure relates generally to the field of mass timber construction. More particularly, the present disclosure relates to connectors in mass timber construction.BACKGROUND OF THE INVENTION

[0003] Mass timber (MT) and wood construction are ubiquitous in the US, known for its cost-effectiveness and for the fact that it requires the least specialized training relative to other materials. The National Design Specification (NDS) provides strength capacity values for wood members, including for typical connections such as nails, screws, and bolts.

[0004] In recent years, a new technology of engineered MT products and construction technologies has developed, known as cross-laminated timber (CLT). Whereas common wood construction comprises relatively slender elements, CLT is used to form panels by gluing the slender elements in layers where the elements in each layer are perpendicular to the adjacent layers. Such panels may be used for multiple building applications, such as floor planks, walls, or deep beams.

[0005] In building construction, it is necessary to connect CLT planks to other members of the building. This is conventionally done using steel plates that connect the two planks using dowel connectors such as large numbers of bolts or screws. These relatively small fasteners are often the weakest link in typical assemblies and do not develop the strength of the connected member.

[0006] In structural design in general, there is consideration for the possibility of overload. This is managed by inflating estimated demands and restricting available member capacity, thereby minimizing the chances of overload. Typically, the magnitude of capacity reduction accounts for uncertainty in the controlling mechanism, that is, the link in the chain of members and connections would fail first; mechanisms with greater dispersion in tested capacity require greater reduction in order to achieve a consistent level of confidence.

[0007] In current practice, CLT construction is characterized by few, large, prefabricated, strong panels joined by many small connectors requiring significant labor on the construction site. In an overload condition, it is unclear what mechanism would control the design, but it appears that few elements in the system have means to deflect in a stable manner without loss of strength (i.e. yield), which would provide occupants the warning sign before catastrophe might occur.SUMMARY OF THE INVENTION

[0008] In one aspect of the present disclosure, a mass timber (MT) construction assembly is provided that includes a first structural member being elongated along a first mating surface having plurality of first connection holes for receiving a plurality of MT panel connectors. The plurality of first connection holes includes a first hole formed from a first bearing surface and first non-bearing surface. The first non-bearing surface is positioned between the first bearing surface and the first mating surface. The MT construction assembly further includes a second structural member connected to the first structural member by the plurality of MT panel connectors to form a portion a framed structure. One or both of the first structural member and second structural member is a MT structural member. The second structural member is elongated along a second mating surface having a plurality of second connection holes for receiving the plurality of MT panel connectors. The plurality of second connection holes comprising a second hole formed from a second bearing surface and second non-bearing surface. The second non-bearing surface being positioned between the second bearing surface and the second mating surface. The first structural member and the second structural member are arranged such that first mating surface contacts the second mating surface and such that the first hole and the second hole are aligned and such that the first non-bearing surface and second non-bearing surface define a free-movement volume. The MT construction assembly further includes a first MT panel connector of the plurality of MT panel connectors. The first MT panel connector connecting the first structural member to the second structural member. The first MT panel connector includes a first bearing portion affixed to the first bearing surface of the first hole, a second bearing portion affixed to the second bearing surface of the second hole, and a fuse portion extending within the free-movement volume and being non-affixed to the first non-bearing surface and second non-bearing surface. The fuse portion is configured to plastically yield within the free-movement volume when an overload is transferred between the first bearing portion and the second bearing portion. The overload causes relative movement between the first structural member and the second structural member such that the first hole and second hole become unaligned while the first bearing portion and second bearing portion respectively do not dislodge from the first bearing surface and the second bearing surface.

[0009] In an embodiment, the fuse portion includes a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion, wherein the fuse portion includes a cross-sectional area that varies between the first tapering portion and the second tapering portion. The cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion.

[0010] In an embodiment, the first bearing portion and second bearing portion include cylindrical surfaces. The first tapering portion and second tapering portion include cylindrical-conical shapes.

[0011] In an embodiment, the first bearing portion and second bearing portion include rectangular surfaces. The first tapering portion and second tapering portion comprise trapezoidal prism surfaces.

[0012] In an embodiment, the first bearing portion and second bearing portion include elliptical surfaces. The first tapering portion and second tapering portion comprise elliptical-conical shapes. In an embodiment, the first structural member is formed from CLT and the first bearing surface is formed from a first sleeve affixed within the first hole.

[0013] In an embodiment, the first structural member is formed from CLT and the first bearing portion of the first MT panel connector is bonded to the first bearing surface.

[0014] In an embodiment, the first structural member is formed from CLT and the first bearing portion of the first MT panel connector is press-fit with the first bearing surface.

[0015] In an embodiment, the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

[0016] In an embodiment, the first structural member and the second structural member each include a CLT panel and form a portion of a wall extending from a floor, and the first mating surface and the second mating surface are parallel to the floor.

[0017] In an embodiment, the first structural member and the second structural member each include a CLT panel and form a portion of a shear wall extending from a floor, and the first mating surface and the second mating surface are perpendicular to the floor.

[0018] In an embodiment, the first structural member and the second structural member each include a CLT panel, and the first structural member is a portion of a ceiling or floor and the second structural member is a portion of a wall.

[0019] In an embodiment, the first structural member includes a CLT panel, and the second structural member includes a column or beam.

[0020] In an embodiment, the first structural member and the second structural member each include a CLT panel. The CLT panel includes panel edges and panel faces. The first mating surface of the first structural member is along a panel edge and the second mating surface of the second structural member is along a panel face.

[0021] In an embodiment, the first structural member and the second structural member each include a CLT panel. The CLT panel includes panel edges and panel faces. The first mating surface of the first structural member is along a first panel face and the second mating surface of the second structural member is along a second panel face.

[0022] In another aspect of the present disclosure, a mass timber (MT) panel connector is provided that includes: a first bearing portion configured to affix to a first MT structural member, a second bearing portion configured to affix to a second MT structural member, and a fuse portion extending between the second bearing portion and the first bearing portion. The first bearing portion extending from a first end towards a second end. The second bearing portion extending from the second end towards the first end. The fuse portion is configured to plastically yield when an overload is transferred between the first bearing portion and the second bearing portion.

[0023] In an embodiment, the fuse portion includes a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion. The fuse portion includes a cross-sectional area that varies between the first tapering portion and the second tapering portion. The cross-sectional area reduces as it extends from the first bearing portion to the mid-fuse portion and increases as it extends from the mid-fuse portion to the second bearing portion. The cross-sectional area is smallest at the mid-fuse portion.

[0024] In an embodiment, a diametrical ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 2 / 3.

[0025] In an embodiment, a width ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 1 / 2.

[0026] In an embodiment, the first bearing portion and second bearing portion include cylindrical surfaces, and the first tapering portion and second tapering portion include cylindrical-conical shapes.

[0027] In an embodiment, the first bearing portion and second bearing portion include rectangular surfaces, and the first tapering portion and second tapering portion include trapezoidal prism shapes.

[0028] In an embodiment, the first bearing portion and second bearing portion include elliptical surfaces, and the first tapering portion and second tapering portion include elliptical-conical shapes.

[0029] In an embodiment, the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.BRIEF DESCRIPTION OF DRAWINGS

[0030] For a better understanding of at least certain embodiments, reference will be made to the following Detailed Description, which is to be read in conjunction with the accompanying drawings.

[0031] FIGS. 1A and 1B illustrates a perspective view and cross-sectional front-view, respectively, of an example general mass timber (MT) panel connector when in a normal (unstressed) state, according to an embodiment.

[0032] FIG. 1C illustrates a cross-sectional front-view of an example general MT panel connector when in an overloaded state, according to an embodiment.

[0033] FIG. 2 illustrates a diagram of an example MT structural member with connection holes for MT panel connectors, according to an embodiment. embodiments.

[0034] FIG. 3 illustrates a diagram of various sizes of connection holes in an edge of example MT structural member, according to an embodiment.

[0035] FIG. 4 illustrates a MT panel connector similar to the MT panel connector of FIGS. 1A-1C, except with bearing portions formed by sleeves, according to an embodiment.

[0036] FIG. 5 illustrates a diagram of an example MT panel connector including bearing portions having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment.

[0037] FIG. 6 illustrates a diagram of an example MT panel connector including bearing portions as sleeves having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment.

[0038] FIG. 7 illustrates a diagram of an example MT panel connector including bearing portions having a cylindrical shape and an elliptical cross-section and tapering portions having a elliptical-conical shape and elliptical cross-section, according to an embodiment.

[0039] FIGS. 8A and 8B illustrates front and side views of the MT panel connector, respectively, according to an embodiment.

[0040] FIG. 8C illustrates a side view of the MT panel connector when plastically yielding due to overload, according to an embodiment.

[0041] FIG. 8D illustrates a perspective view of the MT panel connector 800, according to an embodiment.

[0042] FIG. 9A illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly, according to an embodiment.

[0043] FIG. 9B illustrates a diagram of the MT structural members connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly, as shown in FIG. 9A, during an overload condition causing wall deformation, according to an embodiment.

[0044] FIG. 9C illustrates a diagram of four MT structural members that are connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly during an overload condition, according to an embodiment.

[0045] FIG. 10 illustrates a diagram of MT panel connectors connecting MT structural members in an edge-to-edge connection of an MT construction assembly to form a shear wall, according to an embodiment.

[0046] FIG. 11 illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly to form a wall having a horizontal joint, according to an embodiment.

[0047] FIG. 12 illustrates a diagram of MT panel connectors connecting MT structural members in a face-to-face connection of an MT construction assembly to form built-up shearwall boundary zones, according to an embodiment.

[0048] FIG. 13 illustrates a diagram of an example MT panel connector connecting MT structural members in a face-to-edge connection of an MT construction assembly, according to an embodiment.

[0049] FIG. 14 illustrates a diagram of an MT panel connector connecting MT structural members in a corner connection of an MT construction assembly, according to an embodiment.

[0050] FIG. 15 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment.

[0051] FIG. 16 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment.

[0052] FIG. 17 illustrates a flow chart for a method 1700 for designing MT panel connectors, according to an embodiment.

[0053] FIG. 18 illustrates a cross-sectional front-view of an example round MT panel connector 1800, according to an embodiment.

[0054] FIG. 19 illustrates a front-view of an example CLT panel 1900 with connection holes 1901 (or inputs) configured for use with the MT panel connector 1800 of FIG. 18, according to an embodiment.

[0055] FIG. 20 illustrates a cross-sectional front-view of an example rectangular MT panel connector 2000, according to an embodiment.

[0056] FIG. 21 illustrates a front-view of an example CLT panel 2100 with connection holes 2101 configured for use with the MT panel connector 2000 of FIG. 20, according to an embodiment.

[0057] The figures depict various embodiments of the present invention for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods depicted in the figures may be employed without departing from the principles of the invention described herein.DETAILED DESCRIPTION

[0058] Before the present invention is described in great detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0059] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0060] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.

[0061] It is noted that, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements or use of a "negative" limitation.

[0062] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and depicted herein has discrete components and features which can be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0063] During construction of buildings, mass timber (MT) structural members, such as cross-laminated timber (CLT) planks, are connected to other structural members of the building. This is conventionally done using steel plates that connect, for example, two planks using dowel connectors such as large numbers of bolts or screws. As stated above, these relatively small fasteners are often the weakest link in typical assemblies and do not develop the strength of the connected member.

[0064] In one aspect, a MT panel connector is provided that can be used to connect (or adjoin) MT structural members, such as CLT planks. The MT panel connectors can be inserted into large connection holes prepared in each of the two mating structural members. The connection holes can be shaped precisely to fit the MT panel connector such that the MT panel connector would fit snuggly in each structural member. A series of such MT panel connectors can form the connection between two structural members. The structural members can be joined in the field with the aid of mallets or other hammering devices. The MT panel connectors can be provided with beveled (or tapered) ends and holes to facilitate assembly, fit, and alignment. The MT panel connectors can be formed of many different cross-sectional shapes (e.g. round, rectangular, or elliptical) or of various types of materials (e.g. cold-formed or hot-rolled steel, aluminum, lead, shape memory alloy, wood, composite, or viscoelastic material). The MT panel connector is configured to be inserted within connection holes cored (or drilled) into two structural members, such as planks, boards, ceiling and flooring, walls, beams, etc., in order to connect (or adjoin) the two structural members together. The MT panel connector can connect two structural members together by being partially inserted into a connection hole of one structural member and partially inserted into a corresponding connection hole of the other structural member. The connection holes can be cored within an edge or face of the structural members. When the structural members are connected via the MT panel connector, the mating surfaces (i.e., the edge or face with the connection hole) of the structural members are adjoined with the MT panel connector disposed between and inside the structural members.

[0065] In an embodiment, at least one of the structural members is a MT structural member, and can include a CLT structural member, including CLT planks, panels, boards, walls, beams, etc. In an embodiment, the MT panel connector connects two MT structural members together by being partially inserted into a connection hole of one MT structural member and partially inserted into a corresponding connection hole of the other MT structural member. In an embodiment, the MT panel connector is configured to connect a MT structural member to another structural member that is a non-wood structural member, such as a steel beam for instance.

[0066] The connection holes can be cored into structural members to enable connections between various types of structural members and in various configurations or designs. Example types of structural members can include, for example, panels, planks, walls, beams, etc. The connection holes can be cored into the mating surfaces (e.g., faces or edges) and at varying locations on the structural member, depending on the application, function, or desired use. The connection holes can be pre-cored at predetermined locations during manufacturing, or alternatively can be subsequently cored at locations as desired before use. The structural members can be made of wood or some other suitable material, such as metals, metal alloys, polymeric materials, etc., or combination thereof.

[0067] In one embodiment, the MT panel connectors can connect CLT panels to one another, such as edge-to-edge, to create larger wall or floor assemblies for building. The MT panel connectors cam provide various benefits, such as eliminating the need for screw fasteners, which have limited strength and ductility and are costly and time consuming to install. In an embodiment, the MT panel connector is made of cast steel to facilitate mass production, control material characteristics, and ensure quality manufacture. In an embodiment, the MT panel connectors can include tapered ends to facilitate installation and provide tight-fit in the MT structural members. The fuse portion (or narrow, neck portion) of the MT panel connector is shaped to yield in a ductile and controlled manner, acting as a fuse when overloaded. This characteristic makes it well suited for incorporating into emergent MT seismic resisting walls as connection elements.

[0068] The MT panel connector is an elongated member having a bearing portion at each end of the elongated member with a fuse portion between the bearing portions. The bearing portions are configured to be inserted into the connection holes cored into the structural members and contact the wall of the connection hole. In this way, the bearing portions affix to the MT structural members. An MT structural member can be connected to another structural member (e.g., MT structural member or non-wood structural member) by inserting one bearing portion into a hole cored into the MT structural member and the other bearing portion into a hole cored into the other structural member. The MT panel connector enables the structural members to be connected so that the mating surfaces are adjoined with the MT panel connectors completely disposed within the structural members. In this way, the MT panel connector is similar to a dowel. In contrast, however, the MT panel connector includes the fuse portion disposed between the two mating members. The fuse portion has a smaller width (e.g., diameter) of than the bearing portions and thus forms a free movement volume (or space) within the connection hole that allows the fuse portion to deflect during overload condition. The fuse portion can be designed and formed by any suitable technique, such as milling the MT panel connector, formation via a mold, etc. The MT panel connector member can be made from any suitable material, such as cold-formed or hot-rolled steel, aluminum, lead, shape memory alloy, wood, composite, viscoelastic materials, metals, metal alloys, polymeric materials, etc., or combination thereof. In an embodiment, the MT panel connector is made entirely of cast steel. In another embodiment, the MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

[0069] The bearing portions can vary in shape in different embodiment, such as having a general shape of a cylinder, cuboid, or other suitable geometric or non-geometric shape. For example, in an embodiment, the bearing portion has a cylindrical shape with a cylindrical surface and a circular cross-section. In another embodiment, the bearing portion has a cylindrical shape with a cylindrical surface and an elliptical cross-section. In another embodiment, the bearing portion has a cuboid shape with rectangular surfaces and a rectangular cross-section. In another embodiment, the bearing portion has a cube shape with square surfaces and a square cross-section. The bearing portions can also include a tapered (or beveled) end to assist with insertion into the connection holes. In an embodiment, a bearing portion can include a sleeve that fits over an end of the MT panel connector to form the bearing portion that contacts the bearing surface of the connection hole. The sleeve can be coupled to the MT panel connector to become part of the MT panel connector. For example the sleeve can be sized and shaped to form fit and mechanically couple via frictional fit, or alternatively affixed through any suitable method, such as adhesive, mechanical connection (bolted, screwed, latched, etc.), etc. In an embodiment, one or more bearing surfaces can be formed from a sleeve affixed within a connection hole of a structural member formed from CLT. In an embodiment, one or more first bearing surfaces is bonded to the bearing surface of the connection hole. In an embodiment, one or more bearing surfaces can be press-fit with the bearing surface of the connection hole.

[0070] The width of the bearing portion (or bearing width) can vary depending on various factors, such as size, weight, or density of the structural members, expected load forces or overload conditions, the number of connection holes implemented, etc. Example bearing widths may include, but are not limited to, widths between 0.5 inch and 1 foot, such as between 1 inch and 6 inches, including embodiments with typical widths between 2 inches to 4 inches.

[0071] The fuse portion is positioned in the middle of the MT panel connector between the two bearing portions. The fuse portion has a smaller width and / or diameter (e.g., of the cross-section) than the bearing portions. In an embodiment, the fuse portion decreases generally in width and / or diameter from the bearing portions to a mid-fuse portion (or a middle point between the two bearing portions). In an embodiment, the mid-fuse portion can be halfway between the bearing surfaces in one implementation. In another implementation, the mid-fuse portion can be at another location in between (or in middle of) the bearing surfaces but not necessarily half-way.

[0072] The fuse portion can include a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion. The fuse portion can include a cross-sectional area that varies between the first tapering portion and the second tapering portion, with the cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion. The cross-sectional area is smallest at the mid-fuse portion.

[0073] In some implementations, setting the ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g. bearing portion width) to 2 / 3 can provide peak flexural stress at end of the free movement volume, but eases the stress gradient to increase the length of free movement volume that may yield in the event of overload. This is beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment, a diametrical ratio of the mid-fuse portion to the first bearing portion or the second bearing portion is 2 / 3.

[0074] Because the width (e.g., diameter) of the fuse portion is smaller than the bearing portions, the bearing portions contact adjacent surfaces of the connection holes (also referred to herein as bearing surfaces) while the fuse portion does not contact adjacent surfaces of the connection holes (also referred to herein as non-bearing surfaces). A free movement volume is formed by the space existing between the fuse portion and the non-bearing surfaces. The free movement volume enables the fuse portion to move or flex under overload conditions. In an embodiment, the fuse portion decreases in width (e.g., diameter) from the bearing surfaces to the mid-fuse portion, such as tapering from the bearing portions to the mid-fuse portion. For example, in an embodiment, the first and second bearing portions can include cylindrical surfaces, while first and second tapering portions of the mid-fuse portion can include cylindrical-conical shapes. In another embodiment, the first and second bearing portions can include rectangular surfaces, and the first and second tapering portions include trapezoidal prism shapes. In another embodiment, the first and second bearing portions include elliptical surfaces, and the first and second tapering portions include elliptical-conical shapes.

[0075] The MT panel connectors can provide significant benefits when the structural members are subjected to overload conditions. When the overload is transferred to the MT panel connectors, the MT panel connectors can plastically yield (or flex) within the connection holes in the structural members -- functioning similar to a hinge. The bearing portions remain affixed to the bearing surfaces of the connection hole. Because the fuse portion is adjacent to but not contacting the non-bearing surfaces, the fuse portion can flex during the overload condition. As a result, the structural members that are connected together via the MT panel connectors are able to slide relative to each other under the overload condition. With this in mind, the MT panel connectors can be configured or designed to promote stable, predictable load resistance through a broad range of deflection across the connection.

[0076] The maximum bearing stress in the MT panel connector would occur at the extreme ends of each bearing portion and vary linearly in between. In designing the MT panel connectors, it can be desirable to sufficiently limit this stress to avoid damaging (deforming) the MT panel connector and instead concentrate deformation in free movement volume (or zone) of the MT panel connectors. Internally, the MT panel connectors can experience peak flexural moment at the extreme ends of the free movement volume and vary linearly in between. If the cross section were kept constant through the free movement volume, the flexural stress would follow the same pattern; tapering the MT panel connectors in the free movement volume could be used to dictate within limits the length and location of the zone of peak stress. In an overload condition, ductile (yielding) materials such as metals would undergo plastic rotation concentrated at the locations of peak flexural stress, which would be associated with markedly increased deformation across the connection and energy dissipation.

[0077] The MT panel connectors and corresponding MT construction assemblies can provide significant beneficial features, including: predictable stable load deflection mechanism; concentration of deformation in the MT panel connectors, avoiding damage to wood; fewer parts requiring less labor; better control over the quality of the connection because fewer connectors need to be installed by hand; MT panel connectors are hidden so that connections will have cleaner more seamless aesthetic possibilities; simple, reliable installation method self-aligns connected members; adaptable to multiple materials and manufacturing techniques; etc.

[0078] The MT panel connector can be made from a variety of suitable methods, such as by milling techniques, molding techniques, turning techniques (e.g., lathe work), 3-D printing, etc., or combination thereof. Milling techniques may include, for instance, computer numerical control (CNC) milling, traditional milling, end milling, etc. Molding techniques may include, for instance, injection molding, casting, silicone or 3D-printed molds, etc. Lathe work may include, for instance, live tooling on CNC lathes or a hybrid machine that mills and turns. In one embodiment, the MT panel connector can be made by first creating a general connector using one of the above-mentioned techniques and thereafter removing material in the middle of the connector using one of the above-mentioned techniques to form the tapering portions. Applications of the MT panel connectors with a fuse portion are practically unlimited wherever shear force transfer between structural members, such as CLT planks, is desired. Some example connections can include, but are not limited to: edge to edge connections (e.g. built-up walls), edge to face connections (e.g. plank hung from wall panel), plank to steel beam connection (e.g. composite beam), etc. In one embodiment, the MT panel connector is specifically used as a CLT panel connector that connects a CLT structural member, including CLT planks, panels, boards, walls, beams, etc., to another structural member.

[0079] FIGS. 1A and 1B illustrate a perspective view and a cross-sectional front-view, respectively, of an example general MT panel connector when in a normal (unstressed) state, according to an embodiment. FIG. 1C illustrates a cross-sectional front view of an example general MT panel connector when in an overloaded state, according to an embodiment. FIGS. 1A-1C are described together and features and functions described for one figure may also be applicable to the other figures. For the sake of clarity and brevity, not all common features and functions are repeated for each figure. It should be appreciated that various features and functions described may be applicable to each of the examples shown in FIGS. 1A-1C. In FIG. 1A, a MT panel connector 100 is shown as an elongated member including: bearing portions 101, 102 at respective first and second ends 111, 112 of the MT panel connector 100, and a fuse portion 103 extending between the two bearing portions 101, 102 from the bearing portion101 to the bearing portion 102.

[0080] To facilitate understanding, the MT panel connector 100 is shown connecting a MT structural member 104 to another structural member 105, which can be a MT structural member or a non-wood structural member. The bearing portion 101 is shown inserted within a connection hole 106 cored into a mating surface 108 of the MT structural member 104. The bearing portion 102 is shown inserted within a connection hole 107 cored into a mating surface 109 the structural member 105. The bearing portions 101, 102 and the fuse portion 103 are completely disposed within the connection holes 106, 107 when the mating surfaces 108, 109 are abutting (or flush) with one another along a mating line 110. The bearing portions 101, 102 are shown including optional bevels 120, 121 at the ends 111, 112, respectively, which can assist with insertion of the bearing portions 101, 102 into the connection holes 106, 107 or other connections holes.

[0081] The fuse portion 103 includes tapering portions 113, 114 and a mid-fuse portion 115. The tapering portions 113, 114 extend from respective bearing portions 101, 102 to the mid-fuse portion 115 connecting the tapering portions 113, 114. The tapering portions 113, 114 decrease in cross-sectional area from the respective bearing portions 101, 102 to the mid-fuse portion 115. In an embodiment, the fuse portion 103 has the smallest cross-sectional area at the mid-fuse portion 115.

[0082] When the MT structural member 104 and the structural member 105 are connected by the MT panel connector, the mating surfaces 108, 109 are abutting with the two connection holes 106, 107 aligned creating a cavity where the MT panel connector 100 is completely disposed within. The connection holes 106, 107 include bearing surfaces 116, 117 and non-bearing surfaces 118, 119, respectively. The bearing surfaces 116, 117 are the surfaces within the respective connection holes 106, 107 that contact the bearing portions 101, 102 of the MT panel connector 100 when inserted. The non-bearing surfaces 118, 119 are positioned between the bearing portions 101, 102 and the mating surfaces 108, 109. Because the tapering portions 113, 114 decrease in cross-sectional area from the respective bearing portions 101, 102, the non-bearing surfaces 118, 119 do no contact the tapering portions 113, 114 and a free-movement volume 120 is formed. The free-movement volume 120 is defined by the space (or gap) formed between the tapering portions 113, 114 and the respective non-surface bearing surfaces 118, 119.

[0083] As described above, MT panel connectors are configured to be inserted into connection holes cored into MT structural members to connect MT structural members to other structural members, which may be MT or non-wood structural members. Non-wood structural members can include materials made of metals, metal alloys, polymeric materials, etc. The structural members can include various sized and shaped members but should provide a mating surface for the connection holes and sufficient depth to core a connection hole. Example structural members may include, but are not limited to various panels, planks, boards, ceiling and flooring, walls, beams, etc.

[0084] FIG. 2 illustrates a partially exploded diagram of an example MT structural member with connection holes for MT (e.g., CLT) panel connectors, according to an embodiment. In FIG. 2, the MT structural member 200 is shown as a CLT structural member and having layers 201 of slender wood elements, where the slender elements in each layer are perpendicular to the adjacent layers. The MT structural member is described here specifically as a CLT structural member (e.g. CLT panel) for exemplary purposes and is not intended to be limiting. It should be appreciated that other MT structural members that are not CLT may also be applicable without compromising the underlying principles of the MT panel connectors described herein. The MT structural member 200 is shown as a partially assembled 4-ply, 4-layer panel having two faces 202 and four edges 203. In the example MT structural member 200 shown, the faces 202 refer to the two large faces on top and bottom of the panel, and the four edges 203 refer to the faces on the edges (or sides) of the panel.

[0085] It should be appreciated that the MT structural member 200 is not limited to four layers as shown in FIG. 2 and may include any suitable number of layers and ply. For example, a MT structural member can have three ply and three layers; seven ply and seven layers; nine ply and nine layers; seven ply and five layers 201E; nine ply and seven layers; or any other number of ply and layers.

[0086] The MT structural member 200 is shown having connection holes 204, 205 cored in the faces 202, 203, respectively. It is noted that the connection hole will be present on the mating surface of the fourth layer when fully assembled. The connection holes shown in FIG. 2 are example connection holes and are not intended to be limiting. The connection holes can vary in location, shape, size, number, etc., in different embodiments. The connection holes can be cored into any suitable mating surface, including faces and edges. Therefore, when referring to the connection hole within a mating surface of a MT structural member, it should be appreciated that the mating surface can be a face or edge, unless explicitly stated as limited otherwise.

[0087] FIG. 3 illustrates a diagram of various sizes of connection holes in an edge of example MT structural member, according to an embodiment. In FIG. 3, an edge 303 is shown for a MT structural member 300 having seven ply and seven layers 301. Various sized connection holes 304, 305, 306, 307 are shown cored into the mating surface (or edge in this example) 303 of the MT structural member 300. The size of the connection holes can vary in different embodiments as needed for design specification, and may be based on, for instance, the number of ply or layers, the configuration of the ply and layers, the location of the connection holes, the structural members being connector, the materials of the structural members being connected, the expected function, load, strain, etc. of the structural members being connected, the number of connection holes being implemented, etc. For example, the diameter of the connection hole can be a factor when calculating the available dowel bearing stress perpendicular to the grain, and further, may be weighted as a function of ply thickness and MT panel connector diameter. Generally speaking, example width ranges of connection holes that may be typically used in common construction of buildings may include, but are not limited to, widths between 0.5 inch and 1 foot, such as between 1 inch and 6 inches, including embodiments with typical widths between 2 inches to 4 inches.

[0088] When under stress, such as the MT panel connector 100 encountering force (e.g., load or stress) in an overload condition, the fuse portion 103 and the free-movement volume 120 can limit the force applied to the structural members and reliably control the response of the connection under overload. FIG. 1C illustrates a diagram of the MT panel connector 100 of FIGS. 1A,1B when overloaded, according to an embodiment. In FIG. 1C, the MT structural members 104, 105 are overloaded and moved (or slid) relative to one another. When the overload is transferred between the bearing portions 101, 102, the tapering portions 113, 114 and the free-movement volume 120 enable the fuse portion 103 to plastically yield (or flex) in the free-movement volume 120. The overload causes relative movement between the structural members 104, 105 such that the connection holes 106, 107 can become unaligned. However, because the fuse portion 103 can plastically yield in the free movement volume 120, the bearing portions 101, 102 do not dislodge from (or remain lodged to) the bearing surfaces 116, 117, respectively, when the connection holes 106, 107 become unaligned from the overload. In particular, plastic yielding of the fuse portion 103 can occur at the ends of the free-movement volume 120 where the tapering portions 113 ,114 meet the respective bearing portions 101, 102, functioning similar to a hinge at each location H1,H2 in FIGS. 1A-1C. In some instance, the overload may be sufficient to cause the MT structural members 104, 105 to move resulting in the tapering portions 113, 114 to contact the non-bearing surfaces 118, 119 of the MT structural members 104, 105, as shown in FIG. 1C at contact point CP. In the overload condition, the MT panel connector can deform in a plastic manner by yielding the connector in flexure. The amount of acceptable movement may be limited by: fracture of the MT panel connector, and the bearing of the MT panel connector against the wood in the free movement volume. In an embodiment, the connection hole can be beveled in the wood to increase acceptable deflection.

[0089] Depending on the material implemented and other design factors, the fuse portion can be designed to exhibit different characteristics. Dimensions of the MT panel connector (e.g., the size, width, and shape of the bearing portions, the fuse portion, and the free-movement volume) and can be derived to promote stable, predictable load resistance through a broad range of deflection across the connection. In an embodiment, the ratio of the diameter of the mid-fuse portion 115 to one or both of the diameters of the bearing portions 101, 102 can be set as 2 / 3, or approximately 2 / 3, such as within a tolerance range of 10% or less, including a tolerance range of 5% or less.

[0090] In an embodiment, a MT panel connector can include a sleeve on one or both bearing portions. FIG. 4 illustrates a MT panel connector 400 similar to the MT panel connector 100 of FIGS. 1A-C, except with bearing portions 401, 402 formed by sleeves, according to an embodiment. For the sake of clarity and brevity, similar features and functions are not necessarily described here again but should be understood as still be applicable. The MT panel connector 400 includes bearing portions 401, 402 at respective first and second ends 411, 412 of the MT panel connector 400, and a fuse portion 403 extending between the two bearing portions 401, 402 from the bearing portion 401 to the bearing portion 402. The bearing portions 401, 402 are formed by sleeves S over a dowel (or rod) D. The sleeves S are at the ends 411, 412 of the MT panel connector 400. The sleeves, as the bearing portions 401, 402, contact the bearing surfaces of the connection holes (e.g., the bearing surfaces 116, 117 of the connection holes 106, 107) when the bearing portions 401, 402 are inserted in the connection holes of the two structural members having mating line 510. The fuse portion 103 includes tapering portions 413, 414 and a mid-fuse portion 415. The tapering portions 413, 414 extend from respective bearing portions 401, 402 to the mid-fuse portion 415 connecting the tapering portions 413, 414. The tapering portions 413 , 414 decrease in cross-sectional area from the respective bearing portions 401, 402 to the mid-fuse portion 415. In an embodiment, the fuse portion 403 has the smallest cross-sectional area at the mid-fuse portion 415. A length lb of the bearing portion (also referred to herein as “bearing length”) and a length lf of the free zone (also referred to herein as the “free length”) is shown in FIG. 4 and can be applicable to other MT panel connectors shown in the figures. A width db of the bearing portions 401, 402 is shown and can be applicable to other MT panel connectors. As the MT panel connector 400 includes sleeves S, a width dr is shown to indicate the width of the rod inside the sleeve (i.e., the MT panel connector alone -- without the sleeve).

[0091] It should be appreciated that the shape and size of the MT panel connector 100 and its components (e.g., the bearing portions, 101, 102, the fuse portion 103, the tapering portions 113, 114 of the fuse portion 113, etc.) are not limited to the shape and sizes shown in FIGS. 1A-1C, and can vary in different embodiments. For example, the bearing portions can have a general shape of a cylinder, cuboid, or other suitable geometric or non-geometric shape. In an embodiment, the bearing portions have a cylindrical shape and surface and a circular cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have a cylindrical-conical shape (e.g., a frustum of a cone) and circular cross-section.

[0092] FIG. 5 illustrates a diagram of an example MT panel connector 500 including bearing portions 501, 502 having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1A-C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 500 includes the bearing portions 501, 502 at respective first and second ends 511, 512 of the MT panel connector 500, and a fuse portion 503 extending between the two bearing portions 501, 502 from the bearing portion 501 to the bearing portion 502. The mating line 510 is shown for the two structural members being adjoined. As stated above, the bearing portions 501, 502 have a cylindrical shape and a circular cross-section. While the bearing portions 501, 502 are shown with bevels 520, 521 at their ends, the bevels 520, 521 may not be present in other embodiments. The circular cross-section of the bearing portions 501, 502 is shown with a width (or diameter) db in detail 5A of FIG. 5 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0093] The fuse portion 503 includes tapering portions 513, 514 and a mid-fuse portion 515. The tapering portions 513, 514 extend from respective bearing portions 501, 502 to the mid-fuse portion 515 connecting the tapering portions 513, 514. The tapering portions 513, 514 decrease in cross-sectional area from the respective bearing portions 501, 502 to the mid-fuse portion 515. In an embodiment, the fuse portion 503 has the smallest cross-sectional area at the mid-fuse portion 515. As stated above, the tapering portions 513, 514 have a cylindrical-conical shape and a circular cross-section, which are shown in respective details 5B and 5C of FIG. 5 for reference purposes. In detail 5B of FIG. 5, the truncated cylindrical shape of the tapering portion 514 is shown for reference purposes. The width (or diameter) dend of the larger end of the cylindrical-conical is shown along with the width (or diameter) dmf of the cylindrical-conical at the mid-fuse portion 515. In detail 5C of FIG. 5, the circular cross-section of the tapering portion 514 is shown for reference purposes and has a width (or diameter) dt that decreases from dend to dmf. Similar features apply to the tapering portion 513.

[0094] FIG. 6 illustrates a diagram of an example MT panel connector 600 including bearing portions 601, 602 as sleeves having a cylindrical shape and a circular cross-section and tapering portions having a cylindrical-conical shape and circular cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1, 4 , and 5 are not necessarily described here again but should be understood as still be applicable. The MT panel connector 600 includes sleeves as the bearing portions 601, 602 at respective first and second ends 611, 612 of the MT panel connector 600, and a fuse portion 603 extending between the two bearing portions 601, 602 from the bearing portion 601 to the bearing portion 602. The mating line 610 is shown for the two structural members being adjoined. As stated above, the bearing portions 601, 602 are sleeves having a cylindrical shape and a circular cross-section. While the bearing portions 601, 602 are shown with bevels 620, 621 at their ends, the bevels 620, 621 may not be present in other embodiments. The circular cross-section of the bearing portions 601, 602 is shown with a width (or diameter) db in detail 6A of FIG. 6 for reference purposes. Because the MT panel connector 600 include sleeves, the sleeves are also referenced as sleeves 601, 602 in FIG. 6, which also have widths db. The inner width dr represents the width or diameter within the sleeves 601, 602, or put another way, the width or diameter of the portion of the rod or dowel where the sleeves 601, 602 are coupled to. The mid-fuse portion has a width (or diameter) dmf. In other embodiments, the widths db and dr of the bearing portions 601 may differ from the widths db and dr of the bearing portions 602, respectively.

[0095] The fuse portion 603 includes tapering portions 613, 614 and a mid-fuse portion 615, which are similarly to that in FIG. 5 and thus not repeated here again for the sake of brevity. The tapering portions 613, 614 have a cylindrical-conical shape and a circular cross-section similar to those shown in respective details 6B and 6C of FIG. 5.

[0096] In another embodiment, the bearing portions have a cylindrical shape with an elliptical cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have an elliptical-conical shape (e.g., frustum of a cone having an elliptical) with an elliptical cross-section. FIG. 7 illustrates a diagram of an example MT panel connector 700 including bearing portions 701, 702 having a cylindrical shape and an elliptical cross-section and tapering portions having a elliptical-conical shape and elliptical cross-section, according to an embodiment. For the sake of clarity and brevity, similar features and functions to those shown in FIGS. 1A-1C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 700 includes the bearing portions 701, 702 at respective first and second ends 711, 712 of the MT panel connector 700, and a fuse portion 703 extending between the two bearing portions 701, 702 from the bearing portion 701 to the bearing portion 702. The mating line 710 is shown for the two structural members being adjoined. As stated above, the bearing portions 701, 702 have a cylindrical shape and an elliptical cross-section. The bearing portions 701, 702 can optionally include bevels at their ends in other embodiments. The elliptical cross-section of the bearing portions 701, 702 is shown with a width db (e.g., shown as the major axis of the ellipse) in detail 7A of FIG. 7 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0097] The fuse portion 703 includes tapering portions 713, 714 and a mid-fuse portion 715. The tapering portions 713, 714 extend from respective bearing portions 701, 702 to the mid-fuse portion 715 connecting the tapering portions 713, 714. The tapering portions 713, 714 decrease in cross-sectional area from the respective bearing portions 701, 702 to the mid-fuse portion 715. In an embodiment, the fuse portion 703 has the smallest cross-sectional area at the mid-fuse portion 515. As stated above, the tapering portions 713, 714 have an elliptical-conical shape and an elliptical cross-section, which are shown in respective details 7B and 7C of FIG. 7 for reference purposes. In detail 7B of FIG. 7, the elliptical-conical shape of the tapering portion 714 is shown for reference purposes. The width dend of the larger end of the elliptical-conical shape is shown along with the width dmf of the cylindrical-conical at the mid-fuse portion 715. In detail 7C of FIG. 7, the elliptical cross-section of the tapering portion 714 is shown for reference purposes and has a width dt that decreases from dend to dmf. Similar features apply to the tapering portion 713.

[0098] In yet another embodiment, the bearing portion has a cuboid shape with a rectangular cross-section. The tapering portions can vary in shape in different embodiments, and can be different shapes than one another. In a preferred embodiment, the tapering portions have a trapezoidal prism shape with a rectangular cross-section. FIGS. 8A, 8B, 8C and 8D illustrate diagrams of an example MT panel connector 800 including bearing portions 801, 802 having a cuboid shape and a rectangular cross-section and tapering portions having a trapezoidal prism shape and rectangular cross-section, according to an embodiment. FIGS. 8A and 8B illustrates front and side views of the MT panel connector 800, respectively, according to an embodiment. FIG. 8C illustrates a side view of the MT panel connector 800 when plastically yielding due to overload, according to an embodiment. FIG. 8D illustrates a perspective view of the MT panel connector 800, according to an embodiment. For the sake of clarity and brevity, FIGS. 8A-8D are described together, and similar features and functions to those shown in FIGS. 1A-1C are not necessarily described here again but should be understood as still be applicable. The MT panel connector 800 includes the bearing portions 801, 802 at respective first and second ends 811, 812 of the MT panel connector 800, and a fuse portion 803 extending between the two bearing portions 801, 802 from the bearing portion 801 to the bearing portion 802. The mating line 810 is shown for the two structural members being adjoined. As stated above, the bearing portions 801, 802 have a cuboid shape and a rectangular cross-section. The bearing portions 801, 802 can optionally include bevels at their ends in other embodiments. The rectangular cross-section of the bearing portions 801, 802 is shown with a width db (shown as the major axis of the rectangle) in detail 8A of FIG. 8 for reference purposes. In other embodiments, the widths db of the bearing portions 501, 502 may differ from one another.

[0099] The fuse portion 803 includes tapering portions 813, 814 and a mid-fuse portion 815. The tapering portions 813, 814 extend from respective bearing portions 801, 802 to the mid-fuse portion 815 connecting the tapering portions 813, 814. The tapering portions 813, 814 decrease in cross-sectional area from the respective bearing portions 801, 802 to the mid-fuse portion 815. In an embodiment, the fuse portion 803 has the smallest cross-sectional area at the mid-fuse portion 815. As stated above, the tapering portions 813 ,814 have a trapezoidal prism shape and an rectangular cross-section, which are shown in respective details 8B and 8C of FIG. 8 for reference purposes. In detail 8B of FIG. 8, the trapezoidal prism shape of the tapering portion 814 is shown for reference purposes. The width dend (shown as the major axis of the rectangle) of the larger end of the trapezoidal prism is shown along with the width dmf of the trapezoidal prism at the mid-fuse portion 815. In detail 8C of FIG. 8, the rectangular cross-section of the tapering portion 814 is shown for reference purposes and has a width dt that decreases from dend to dmf. Similar features apply to the tapering portion 713.

[0100] In the overload condition, the MT panel connector 800 can deform in a plastic manner by yielding the connector in flexure. By sufficiently beveling the connection hole in the wood, it can be enable the steel to fracture prior to the connector bearing against the wood, which may be desirable in certain applications.

[0101] Setting the ratio of tapered to full bearing portion width to 0.5 can ensure peak flexural stress at end of free movement volume, but eases the stress gradient to increase the length of free zone that may yield in the event of overload. This is beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment, a width ratio of the mid-fuse portion to the first bearing portion or second bearing portion is ½.

[0102] It should be appreciated that other embodiments are also possible, such as the bearing portion having a cube shape with square surfaces and a square cross-section. The tapering portions have a trapezoidal prism shape with a trapezoidal prism surface and rectangular cross- section. For the sake of clarity and brevity, not every variation is shown in a figure and described.

[0103] In use, the MT panel connectors are inserted within holes that are cored into MT structural members. The MT structural members can include, for example, panels, planks, walls, beams, etc., with connection holes drilled into its faces and / or edges, depending on the application, function, or desired use. The MT structural members can be manufactured with the connection holes pre-cored at predetermined locations, or alternatively can be subsequently drilled at various locations as desired. The MT structural members can be wood or some other material, such as metals, metal alloys, polymeric materials, etc., or combination thereof.

[0104] When two MT structural members are selected for connection, with the corresponding connection drilled into appropriate locations, an MT panel connectors can be inserted into one or more connection holes in one of the MT structural members (e.g., wood structural member) and then the exposed portions of the MT panel connectors can then be inserted into the corresponding connection holes in the other MT structural member (e.g., wood or non-wood structural member) until the mating surfaces are abutting. In some instance, force may be applied to one or both of the MT structural members to drive the MT panel connectors completely into the connection holes so that the mating surfaces abut. Hammers or other hammering tools may also be used to assist with the completely adjoining the structural members via the MT panel connectors. This process can be repeated for additional connections between either of the two MT structural members and other MT structural members as desired.

[0105] Applications of the MT panel connectors with a fuse portion are practically unlimited wherever shear force transfer between structural members, such as CLT planks, is desired. Some example connections can include: edge to edge connections (e.g. built-up walls); edge to face connections (e.g. plank hung from wall panel); plank to steel beam connections (e.g. composite beam). It should be appreciated that parallel attachments also can be implemented to transfer moment demands between panels.

[0106] FIGS. 9-16 are provided below and describe various example MT construction assemblies (e.g., CLT construction assemblies) including structural members connected via MT panel connectors. It should be appreciated that the previous discussion for FIGS. 1-8 may also be applicable for FIGS. 9-16 and not every common feature or variation is repeated here again for the sake of clarity and brevity. It should also be appreciated that while the example MT construction assemblies may include structural members or MT structural members that are adjoined to form a portion of a framed structure, the description may also be applicable to MT construction assemblies for other structural members than shown. The examples shown are for explanatory purposes and are not intended to be limiting. One example MT construction assembly includes various types and configurations of stacked panel walls (e.g., panel shear walls). Such MT construction assemblies MT and MT panel connectors use can provide many advantages, such as being self aligning, enable simple fit and installation, result in no exposed fasteners, enable strong shear connections, being suitable and practical for frame buildings, applicable to wall and floor assemblies, provide for a compact and efficient shear wall assembly, enable rapid installation, customizable to vary in size, strength, and shape based on panel thickness, etc.

[0107] FIG. 9A illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly, according to an embodiment. In FIG. 9A, MT panel connectors 900 are shown connecting MT structural member 904 with MT structural member 905 to form a portion of a framed structure – e.g., a wall connected with a vertical joint at the edges of the MT structural members. The mating line 910 is shown between structural members 904 and 905. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0108] FIG. 9B illustrates a diagram of the MT structural members 904, 905 connected with MT panel connectors in an edge-to-edge connection of an MT construction assembly, as shown in FIG. 9A, during an overload condition causing wall deformation. When the MT structural members 904 and 905 undergo stress or force it can cause an overload condition which transfers force to the MT panel connector 900. In the overload condition, the fuse portion 103 and the free-movement volume 120 of the MT panel connectors 900 can limit the force in the MT panel connector 900 and the MT structural members 904 and 905 to reliably control the response of the connection under overload. The MT structural members 904 and 905 are overloaded and moved (or slid) relative to one another. As previously described for FIG. 1C and referred to here again for FIG. 9B, when the overload is transferred between the bearing portions 101, 102 of the MT panel connectors 900, the tapering portions 113, 114 and the free-movement volume 120 enable the fuse portion 103 to plastically yield (or flex) in the free-movement volume 120. The overload causes relative movement between the MT structural members 904 and 905 such that the connection holes 106, 107 can become unaligned. However, because the fuse portion 103 can plastically yield in the free movement volume 120, the bearing portions 101, 102 remain lodged to the bearing surfaces 116, 117, respectively. In particular, plastic yielding of the fuse portion 103 of the MT panel connectors 900 can occur at the ends of the free-movement volume 120 where the tapering portions 113, 114 meet the respective bearing portions 101, 102, functioning similar to a hinge at each location H1,H2. This enables the wall to deform when overloaded.

[0109] FIG. 9C illustrates a diagram of four MT structural members 904, 905, 906, 907 that are connected with MT panel connectors 900 in an edge-to-edge connection of an MT construction assembly during an overload condition, according to an embodiment. .In FIG. 9C, MT panel connectors 900 are shown connecting the MT structural member 904 with the MT structural member 905, the MT structural member 905 with MT structural member 906, and the MT structural member 906 with MT structural member 907 to form a portion of a framed structure – e.g., a wall connected with a vertical joint at the edges of the MT structural members. The overload causes wall deformation between the adjacently connected MT structural members connected via MT panel connectors, as similarly described for FIG. 9B. This is not limited to 2 or 4 panels as shown, but can be applicable to any number of panels connected via the MT panel connectors.

[0110] In design to resistance to seismic demands, ductility is an important property of the Lateral Force Resisting System (LFRS). Ductility is the ability for a member to deform in a plastic manner without loss of stress. This property dampens the movement of a structure during an earthquake, effectively limiting lateral displacement and promoting stability. The amount of ductility desired generally correlates with the intensity of seismic demands expected at a given site. In certain aspects, steel MT panel connectors are configured to yield in a ductile manner, precluding nonductile bearing and crushing of the wood. In a CLT wall system, for instance, planks may be joined together to form larger walls capable of resisting earthquake demands. In certain applications, better seismic performance can be accomplished through joining panels along vertical seams between muti-story CLT planks instead of joining panels along horizontal seams. For instance, slender panels may dissipate energy along the vertical seams and rock back into place when the earthquake, and the amount of ductility desired is achievable simply by specifying the number of vertical seams (horizontal seams offer ductility limited to a single seam). As shown in FIGS. 9B and 9C, the system ductility varies linearly with one-half the number of sub-panels.

[0111] FIG. 10 illustrates a diagram of MT panel connectors connecting MT structural members in an edge-to-edge connection of an MT construction assembly to form a portion of a framed structure – e.g., a shear wall, according to an embodiment. For example, in FIG. 10, MT panel connectors 1000 are shown inserted within MT structural member 1004 and used for connection to MT structural members 1005A and 1005B. In FIG. 10, the MT structural member 1004 is already connected to the MT structural member 1005B, with the MT panel connectors 1000 fully inserted within the connection holes of the mating surface of the MT structural member 1004 and the edge of the MT structural member 1005B. Some of the MT panel connectors 1000 are shown already inserted into and exposed from (or protruding from) the mating surface of the MT structural member 1004. The exposed MT panel connectors 1000 can then be inserted within connection holes on the edge of the to the MT structural member 1005A to connect the MT structural members 1004 and 1005A. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0112] FIG. 11 illustrates a diagram of MT panel connectors connecting two MT structural members in an edge-to-edge connection of an MT construction assembly to form a portion of a framed structure – e.g., a wall having a horizontal joint, according to an embodiment. In FIG. 11, MT panel connectors 1100 are shown connecting MT structural member 1104 with MT structural member 1105 to form a wall having a vertical joint at the edges of the MT structural members. The mating line 110 is shown for the two structural members 1105, 1105 being adjoined. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT planks for instance. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces parallel to the floor.

[0113] FIG. 12 illustrates a diagram of MT panel connectors connecting MT structural members in a face-to-face connection of an MT construction assembly to form a portion of a framed structure – e.g., built-up shearwall boundary zones, according to an embodiment. For example, in FIG. 12, MT panel connectors 1200 are shown inserted within MT structural member 1204 and used for connection to MT structural members 1205A, 1205B, 1205C, and 1205D. Some of the MT panel connectors 1200 are connecting the MT structural members 1204 and 1205A through connections holes in their corresponding mating surfaces. Further, some of the MT panel connectors 1200 are connecting the MT structural members 1204 and 1205B through connections holes in their corresponding mating surfaces. This is similarly done with the MT structural members 1204 and 1205C, as well as MT structural members 1204 and 1205D, through connections holes in their corresponding mating surfaces. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT planks for instance. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, to form a portion of a wall extending from a floor with the mating surfaces perpendicular to the floor.

[0114] FIG. 13 illustrates a diagram of an example MT panel connector connecting MT structural members in a face-to-edge connection of an MT construction assembly, according to an embodiment. For example, in FIG. 13, an MT panel connector 1300 is shown inserted within, and connecting, a MT structural member 1304 (e.g., a CLT wall plank) and a MT structural member 1305 (e.g., a CLT floor plank) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, and the first CLT structural member is a portion of a ceiling or floor and the second CLT structural member is a portion of a wall.

[0115] FIG. 14 illustrates a diagram of an MT panel connector connecting MT structural members in a corner connection of an MT construction assembly, according to an embodiment. For example, in FIG. 14, an MT panel connector 1400 is shown inserted within, and connecting, a MT structural member 1404 (e.g., a CLT wall plank) and a MT structural member 1405 (e.g., a CLT floor plank) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting CLT structural members, such as CLT panels, and the first CLT structural member is a portion of a ceiling or floor and the second CLT structural member is a portion of a wall.

[0116] FIG. 15 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment. For example, in FIG. 15, an MT panel connector 1500 is shown inserted within, and connecting, a MT structural member 1504 (e.g., a CLT floor plank) and a MT structural member 1505 (e.g., a wood beam) to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting a CLT structural member, such as a CLT panel, and a second structural member including a column or beam.

[0117] FIG. 16 illustrates a diagram of an MT panel connector connecting MT structural members in a composite connection of an MT construction assembly, according to an embodiment. For example, in FIG. 16, an MT panel connector 1600 is shown inserted within, and connecting, a MT structural member 1604 (e.g., a CLT floor plank) and a structural member 1605 (e.g., a steel beam). One bearing surface 1606 of the MT panel connector 1600 is inserted within the connection hole of the MT structural member 1604. The other bearing surface 1607 is connected to the structural member 1605 and also disposed within the connection hole of the MT structural member 1604 to form a portion of a framed structure. In an embodiment, the MT panel connectors are connecting a CLT structural member, such as a CLT panel, and a second structural member including a column or beam. In one implementation where the structural member 1605 is made from steel, such as with a steel beam, the MT panel connector 1600 can be fabricated from standard structural steel material grades and welded to the steel member 1605.

[0118] In one aspect of the present disclosure, methods are provided for designing MT panel connectors, such as the MT panel connectors discussed herein and shown in the figures. FIG. 17 illustrates a flow chart for a method 1700 for designing MT panel connectors, according to an embodiment. FIG. 18 illustrates a cross-sectional front-view of an example round MT panel connector 1800, according to an embodiment. FIG. 19 illustrates a front-view of an example CLT panel 1900 with connection holes 1901 (or inputs) configured for use with the MT panel connector 1800 of FIG. 18, according to an embodiment. FIG. 20 illustrates a cross-sectional front-view of an example rectangular MT panel connector 2000, according to an embodiment. FIG. 21 illustrates a front-view of an example CLT panel 2100 with connection holes 2101 configured for use with the MT panel connector 2000 of FIG. 20, according to an embodiment. FIGS. 17 is described below in conjunction with the specific examples shown in FIGS. 18 and 19, as well as FIGS. 20 and 21.

[0119] In FIG. 18, the MT panel connector 1800 is shown in MT structural members 1804, 1805 and includes bearing portions 1801, 1802, mid-fuse portion 1803, and a mating line 1810. One of the sleeves (sleeve 1811) is also shown coupled to (or fit) over a dowel (or rod) portion D of the MT panel connector 1800. Also shown is a bevel hole 1812 and bevel 1821, which can be implemented in some embodiments to ease installation. The bearing portions 1801, 1802 are shown with a width db (equal to the width of the sleeve) and lengths lb (may also be referred to as the bearing length). The rod D is shown with a width dr. One of the tapered portions (tapered portion 1813) is shown with a length lf (may also be referred to herein as the free length). The tapered portion 1813 has a width dmf at the mating line 1810 (i.e., at the mid-fuse portion). It should be appreciated that not all features of the MT panel connector has been described here for the sake of clarity and brevity, however applicable features from other figures may equally apply here.

[0120] Similarly, in FIG. 20, the MT panel connector 2000 is shown in MT structural members 2004, 2005 and includes bearing portions 2001, 2002, mid-fuse portion 2003, and a mating line 2010. One of the sleeves (sleeve 2011) is also shown coupled to (or fit) over a dowel (or rod) portion D of the MT panel connector 2000. Also shown is a bevel hole 2012 and bevel 2021, which can be implemented in some embodiments to ease installation. The bearing portions 2001, 2002 are shown with a width db and lengths lb (also referred to as the bearing length). The rod is shown with a width dr. One of the tapered portions (tapered portion 2013) is shown with a length lf (also referred to as the free length). The tapered portion 1813 has a width dmf at the mating line 1810 (i.e., at the mid-fuse portion). It should be appreciated that not all features of the MT panel connector has been described here for the sake of clarity and brevity, however applicable features from other figures may equally apply here.

[0121] In FIG. 17, a method 1700 for designing a MT panel connector is shown, such as the MT panel connectors 1800 and 2000. At block 1705 of the method 1700, a target sheer strength per MT panel connector is determined. The target sheer strength depends on the properties of the CLT panel (e.g., CLT plank) and MT panel connector spacing S. Example CLT panels 1900 and 2100 are shown in FIGS. 19 and 21 along with associated MT panel connector spacings S between the connection holes 1901 and 2101, respectively. An available shear stress (Fv) of the CLT panel can be obtained from the CLT manufacturer’s specification. The target MT panel connector strength (Vtarg) can be calculated as the shear stress (Fv) multiplied by the MT panel connector spacing S and the CLT panel thickness (tCLT).

[0122] At block 1710, an MT panel connector material is selected and its associated flexural and shear yield stresses (Fy,r) and (Fv,r) are determined. At block 1715, specifications for the MT panel connector and the connection holes are selected. For example, in the example round MT panel connector 1800 for FIGS. 18 and 19, a bearing portion width db and rod width dr can be selected. The rod width dr can also be seen in in FIG. 6, and can be equivalent to dend shown in FIG. 5. In the example rectangular MT panel connector 2000 for FIGS. 20 and 21, a thickness (tr), bearing portion width (db), and free zone width (or width dr) can be selected.

[0123] At block 1720, a ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g., bearing portion width) is selected. In an embodiment for the round MT panel connector for FIGS. 18 and 19, setting the ratio of the tapered width (e.g., mid-fuse portion width) to full connector width (e.g. bearing portion width) to 2 / 3 can provide peak flexural stress at end of the free movement volume, but eases the stress gradient to increase the length of free movement volume that may yield in the event of overload. This can be beneficial from the standpoint of energy dissipation and forestalling fracture. In an embodiment for the rectangular MT panel connector for FIGS. 20 and 21, setting the ratio of tapered width to full bearing portion width to 1 / 2 (or 0.5) can ensure peak flexural stress at end of free movement volume, but eases the stress gradient to increase the length of free zone that may yield in the event of overload. This can be beneficial from the standpoint of energy dissipation and forestalling fracture.

[0124] At block 1725, a reduction factor (ød) is selected that will limit usage of wood bearing stress and thereby ensure MT panel connector yielding precludes and prevents excessive bearing stress. In an embodiment, a factor of 2 / 3 is reasonable given steel strain hardening.

[0125] At block 1730, critical values lf and lb are determined. Without the benefit of a solver, combinations of the two critical dimensions lf and lb can be tried such that the following two conditions are met: 1. peak MT panel connector flexural stress (at edge of the free zone) equals MT panel connector yield stress Fy,r, and 2. MT panel connector shear force equals target shear force (constrained by shear strength of CLT panel): V=Vtarg. Note that if the MT panel connector diameter is too small, shear yield of the dowel can control the design, resulting in a shear capacity less than Vtarg, which may be a suboptimal use of the MT panel connector in some cases. With the help of a solver, the unique values of the two critical dimensions lf and lb (free length and bearing length, respectively) may be found with desired accuracy.

[0126] Example measurements for the free length lf and bearing length lb of the MT panel connectors may include, but are not limited to, values within the range from 0.2 inches to 6 inches for the free length lf; and values within the range from 2 inches to 10 inches for the bearing length lb. In an embodiment, the free length lf of the MT panel connector is a value within 0.4 inches and 4.2 inches, while the bearing length lb is a value within 4 inches and 8.25 inches.

[0127] It should be appreciated that other variations are contemplated and not every variation is provided as an example. For example, the first structural member and the second structural member can each include a CLT panel that includes panel edges and panel faces. In one implementation, the mating surface of the first structural member can be along a first panel face and the mating surface of the second structural member can along a second panel face. In another implementation, the mating surface of the first structural member can also be along a first panel edge and the mating surface of the second structural member can be along a second panel face.

[0128] Throughout the foregoing description, and for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the described techniques. It will be apparent, however, to one skilled in the art that these techniques can be practiced without some of these specific details. Although various embodiments that incorporate these teachings have been shown and described in detail, those skilled in the art could readily devise many other varied embodiments or mechanisms to incorporate these techniques. Also, embodiments can include various operations as set forth above, fewer operations, or more operations; or operations in an order. Accordingly, the scope and spirit of the invention should be judged in terms of the claims, which follow as well as the legal equivalents thereof.

Examples

Embodiment Construction

[0058]Before the present invention is described in great detail, it is to be understood that this invention is not limited to particular embodiments described, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0059]Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges can independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated ran...

Claims

1. A mass timber (MT) construction assembly comprising:a first structural member being elongated along a first mating surface having plurality of first connection holes for receiving a plurality of MT panel connectors, the plurality of first connection holes comprising a first hole formed from a first bearing surface and first non-bearing surface, the first non-bearing surface being positioned between the first bearing surface and the first mating surface;a second structural member connected to the first structural member by the plurality of MT panel connectors to form a portion a framed structure, wherein one or both of the first structural member and second structural member is a MT structural member, the second structural member being elongated along a second mating surface having a plurality of second connection holes for receiving the plurality of MT panel connectors, the plurality of second connection holes comprising a second hole formed from a second bearing surface and second non-bearing surface, the second non-bearing surface being positioned between the second bearing surface and the second mating surface, the first structural member and the second structural member being arranged such that first mating surface contacts the second mating surface and such that the first hole and the second hole are aligned and such that the first non-bearing surface and second non-bearing surface define a free-movement volume;a first MT panel connector of the plurality of MT panel connectors, the first MT panel connector connecting the first structural member to the second structural member, the first MT panel connector comprising first bearing portion affixed to the first bearing surface of the first hole, a second bearing portion affixed to the second bearing surface of the second hole, and a fuse portion extending within the free-movement volume and being non-affixed to the first non-bearing surface and second non-bearing surface,wherein the fuse portion is configured to plastically yield within the free-movement volume when an overload is transferred between the first bearing portion and the second bearing portion, the overload causing relative movement between the first structural member and the second structural member such that the first hole and second hole become unaligned while the first bearing portion and second bearing portion respectively do not dislodge from the first bearing surface and the second bearing surface.

2. The MT construction assembly of claim 1, wherein the fuse portion comprises a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion, wherein the fuse portion comprises a cross-sectional area that varies between the first tapering portion and the second tapering portion, the cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion.

3. The MT construction assembly of claim 2, wherein the first bearing portion and second bearing portion comprise cylindrical surfaces, and wherein the first tapering portion and second tapering portion comprise cylindrical-conical shapes.

4. The MT construction assembly of claim 2, wherein the first bearing portion and second bearing portion comprise rectangular surfaces, and wherein the first tapering portion and second tapering portion comprise trapezoidal prism surfaces.

5. The MT construction assembly of claim 2, wherein the first bearing portion and second bearing portion comprise elliptical surfaces, and wherein the first tapering portion and second tapering portion comprise elliptical-conical shapes.

6. The MT construction assembly of claim 1, wherein the first structural member is formed from CLT and wherein the first bearing surface is formed from a first sleeve affixed within the first hole.

7. The MT construction assembly of claim 1, wherein the first structural member is formed from CLT and wherein the first bearing portion of the first MT panel connector is bonded to the first bearing surface.

8. The MT construction assembly of claim 1, wherein the first structural member is formed from CLT and wherein the first bearing portion of the first MT panel connector is press-fit with the first bearing surface.

9. The MT construction assembly of claim 1, wherein the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

10. The MT construction assembly of claim 1, wherein the first structural member and the second structural member each comprise a CLT panel and form a portion of a wall extending from a floor, and wherein the first mating surface and the second mating surface are parallel to the floor.

11. The MT construction assembly of claim 1, wherein the first structural member and the second structural member each comprise a CLT panel and form a portion of a wall extending from a floor, and wherein the first mating surface and the second mating surface are perpendicular to the floor.

12. The MT construction assembly of claim 1, wherein the first structural member and the second structural member each comprise a CLT panel, and wherein the first structural member is a portion of a ceiling or floor and the second structural member is a portion of a wall.

13. The MT construction assembly of claim 1, wherein the first structural member comprises a CLT panel, and wherein the second structural member comprises a column or beam.

14. The MT construction assembly of claim 1, wherein the first structural member and the second structural member each comprise a CLT panel, the CLT panel comprising panel edges and panel faces, and wherein the first mating surface of the first structural member is along a panel edge and wherein the second mating surface of the second structural member is along a panel face.

15. The MT construction assembly of claim 1, wherein the first structural member and the second structural member each comprise a CLT panel, the CLT panel comprising panel edges and panel faces, and wherein the first mating surface of the first structural member is along a first panel face and wherein the second mating surface of the second structural member is along a second panel face.

16. A mass timber (MT) panel connector comprising:a first bearing portion configured to affix to a first MT structural member, the first bearing portion extending from a first end towards a second end,a second bearing portion configured to affix to a second MT structural member, the second bearing portion extending from the second end towards the first end,a fuse portion extending between the second bearing portion and the first bearing portion, wherein the fuse portion is configured to plastically yield when an overload is transferred between the first bearing portion and the second bearing portion.

17. The MT panel connector of claim 16, wherein the fuse portion comprises a first tapering portion extending from the first bearing portion, a second tapering portion extending from the second bearing portion, and a mid-fuse portion connecting the first tapering portion and the second tapering potion, wherein the fuse portion comprises a cross-sectional area that varies between the first tapering portion and the second tapering portion, the cross-sectional area reducing as it extends from the first bearing portion to the mid-fuse portion and increasing as it extends from the mid-fuse portion to the second bearing portion, wherein the cross-sectional area is smallest at the mid-fuse portion.

18. The MT panel connector of claim 17, wherein a diametrical ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 2 / 3.

19. The MT panel connector of claim 17, wherein a width ratio of the mid-fuse portion to the first bearing portion or second bearing portion is 1 / 2.

20. The MT panel connector of claim 17, wherein the first bearing portion and second bearing portion comprise cylindrical surfaces, and wherein the first tapering portion and second tapering portion comprise cylindrical-conical shapes.

21. The MT panel connector of claim 18, wherein the first bearing portion and second bearing portion comprise rectangular surfaces, and wherein the first tapering portion and second tapering portion comprise trapezoidal prism shapes.

22. The MT panel connector of claim 19, wherein the first bearing portion and second bearing portion comprise elliptical surfaces, and wherein the first tapering portion and second tapering portion comprise elliptical-conical shapes.

23. The MT panel connector of claim 16, wherein the first MT panel connector is formed from an iron, steel, aluminum, lead, shape-memory alloy, wood, polymer, elastomer, composite, and / or viscoelastic material.

Images