Variable stiffness wooden beam, building structure and preparation method

Abstract

The present invention discloses a variable stiffness wooden beam, a building structure and a preparation method, which belong to the field of civil engineering. A composite wooden beam with a large height-to-span ratio is formed by stacking multiple layers of flat wooden board sheets. The combined action between the stacked flat beams of each layer is achieved by structures such as (1) hook and loop fasteners of the stacked layers, (2) end caps of the stacked wooden beams and (3) FRP composite material hoops on the stacked wooden beams. That is, the above structures provide a function similar to a shear key of the composite beam to form a complete or partial shear connection between the stacked beams. In the variable stiffness wooden beam provided by the present invention, under a severe earthquake, the FRP composite material hoops and the end caps are deformed and fail, and at the same time, the hook and loop fasteners slip, causing the combined action between the stacked layers to fail, thereby reducing the stiffness of the composite beam and being able to adapt to the large deformation requirements under a severe earthquake without causing breakage of the wooden beam or the node.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, and in particular to a wood beam with variable stiffness. Background Art

[0002] In the construction and production process, protecting the ecological environment and achieving energy conservation, land conservation, and material conservation have become new goals. Wood structures have many characteristics such as easy material acquisition and processing, low carbon and environmental protection, and recyclability. In addition, they have a short construction period and good thermal insulation performance. Wood structure buildings will have great application and development space in the future. Due to the characteristics of wood materials, the cross-sectional height of wooden beams with large spans is generally much greater than the height of steel beams or concrete beams under the same load level. In practice, the acquisition and manufacture of large-section wooden beams are subject to certain restrictions, which affects the application scenarios of wooden structures. On the other hand, due to the low strength of wood, large-section wooden beams lack the ability to adapt to large deformations in actual use. For example, they are prone to breaking in the event of a major earthquake, or the beam-column joints are damaged or dislocated. This also makes the so-called good energy consumption characteristics of wooden structures unable to be effectively exerted and truly reflected. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention proposes a variable stiffness wooden beam. By constructing and combining small-section wooden beams with a wide area and large quantity, a large-section wooden beam with variable stiffness and energy dissipation characteristics is formed. The large-section wooden beam can not only maintain sufficient stiffness under normal use loads, but also release stiffness through interlayer sliding under major earthquake conditions, thereby avoiding fracture and damage of the wooden beam, and at the same time relying on interlayer friction to achieve effective energy dissipation.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A first aspect of the present application provides a variable stiffness wooden beam, comprising:

[0006] Wooden beam pieces, the wooden beam pieces are stacked by bonding with hook and loop fasteners;

[0007] Closing plates, the closing plates are symmetrically arranged on both sides of the wooden beam pieces; the superimposed body of the wooden beam pieces is connected to the closing plates;

[0008] The FRP composite material tightly embraces the laminated body of the wood beam sheets.

[0009] In some embodiments, among the two adjacent wooden beam pieces, one wooden beam piece is installed with the hairy surface of the parent-child Velcro, and the other wooden beam piece is installed with the hook surface of the parent-child Velcro; the hairy surface of the parent-child Velcro is alignably connected with the hook surface of the parent-child Velcro.

[0010] In some embodiments, the dimensions of the wood beam pieces are limited to a height-to-width ratio of less than or equal to 0.3.

[0011] In some embodiments, the FRP composite material is evenly spaced across the stack of wood beam sheets.

[0012] In some embodiments, the wooden beams are bonded to the hook and loop fasteners, the sealing plate and the FRP composite material by epoxy resin glue.

[0013] A second aspect of the present application provides a building structure constructed by using the variable-rigidity wooden beam according to the first aspect of the present application.

[0014] A third aspect of the present application provides a method for preparing a variable-rigidity wooden beam as described in the first aspect of the present application, characterized in that it comprises the following steps:

[0015] The hook side and the hair side of the parent-child hook and loop fastener are respectively adhered to both sides of the wooden beam piece; wherein the wooden beam pieces of the first layer and the bottom layer are only adhered to the hook side or the hair side of the parent-child hook and loop fastener adhered to the adjacent layer;

[0016] The wooden beam pieces are bonded and overlapped by means of the hook surface and the hair surface of the parent-child hook and loop fastener; and the sealing plates are bonded to both sides of the overlapped body of the wooden beam pieces;

[0017] The FRP composite material is tightly embraced by the superposition body of the wood beam pieces, and the FRP composite material and the superposition body of the wood beam pieces are bonded.

[0018] Beneficial effects of the present invention:

[0019] The present invention forms a composite wooden beam with a large height-to-span ratio by stacking multiple layers of flat wooden sheets. The combined effect between the stacked flat beams is achieved by structures such as (1) hook and loop fasteners (HOOK&LOOP) of the stacked layers, (2) sealing plates at both ends of the composite wooden beam, and (3) FRP composite materials on the composite wooden beam. That is, the above-mentioned structure provides a function similar to a shear key of the composite beam to form a complete or partial shear connection between the composite beams.

[0020] The variable-stiffness timber beams provided by this invention, when subjected to a major earthquake, experience deformation and failure of the FRP composite material and end capping panels. Simultaneously, the Velcro straps slip, causing the interlaminar interaction to fail. This reduces the stiffness of the composite beam, allowing it to accommodate the large deformations required during a major earthquake without causing breakage at the beam or joints. Furthermore, each layer of the stacked flat beams remains elastic during a major earthquake, allowing for deformation recovery, facilitating post-earthquake repair work.

[0021] The present invention utilizes parent-child Velcro as the overlapping layer of the wooden beam pieces. The large deformation under a large earthquake also enables the friction layer formed by each layer of the parent-child Velcro to obtain a large sliding friction stroke, which can effectively dissipate energy. At the same time, the characteristic of the parent-child Velcro that the Velcro can quickly restore the fastening force after the sliding stops is utilized to avoid a sharp drop in the residual bearing capacity of the wooden beam, thereby preventing the sudden collapse of the structure that may occur after being damaged by an earthquake.

[0022] The wooden beam provided by the present invention is composed of standard wooden beam pieces, parent-child Velcro, FRP composite materials and sealing plates. When some standard parts are damaged, the structure can be repaired by replacing local components, which solves the problem that wooden beams are difficult to repair after being damaged, and reflects the recoverability of the wooden beams provided by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 A schematic diagram of a three-dimensional structure of a wood beam with variable stiffness provided by the present invention;

[0025] Figure 2 It is a schematic diagram of the three-dimensional structure of the mother-and-child hook and loop fasteners bonded to the standard-layer wood beams of the present invention;

[0026] Figure 3 It is a schematic diagram of the three-dimensional structure of the position of the parent-child hook and loop fastener of the present invention;

[0027] Figure 4 An exploded view of a variable stiffness wooden beam according to the present invention;

[0028] Figure 5 This is a schematic diagram of assembling the wooden beam pieces of the present invention by aligning and bonding them with the parent-child hook and loop fasteners;

[0029] Figure 6 It is a schematic diagram of the assembly of the overlapping body of the cover plate and the wooden beam piece according to the present invention;

[0030] Figure 7 Schematic diagram of the assembly process for forming a wooden beam hoop for the FRP composite material;

[0031] Figure 8 The present invention provides a cross-sectional schematic diagram of a 6-layer laminated variable stiffness wooden beam and a non-layered whole beam; wherein (a) is a cross-sectional schematic diagram of the 6-layer laminated variable stiffness wooden beam, and (b) is a cross-sectional schematic diagram of the non-layered whole beam.

[0032] Figure numerals: 1. wooden beam; 2. mother-and-child hook and loop fastener; 201. hairy surface of mother-and-child hook and loop fastener; 202. hook surface of mother-and-child hook and loop fastener; 3. sealing plate; 4. FRP composite material. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "around" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0035] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0036] Example 1: Figure 1 As shown, the present invention provides a variable stiffness wooden beam, which includes a wooden beam piece 1, a parent-child hook and loop fastener 2, a sealing plate 3 and an FRP composite material 4.

[0037] like Figure 2 As shown, the mother-and-child hook and loop fastener 2 includes a hair surface 201 and a hook surface 202 of the mother-and-child hook and loop fastener. The wood beam 1 is aligned and bonded to the mother-and-child hook and loop fastener 2 in the order of the first layer, the standard layer, and the bottom layer using epoxy resin glue. Figure 2 The standard layer wooden beam piece 1 is shown. Specifically, the upper surface of the wooden beam piece 1 is bonded with the rough surface 201 of the parent-child hook and loop fastener, and the lower surface is bonded with the hook surface 202 of the parent-child hook and loop fastener.

[0038] like Figure 3 As shown, this embodiment utilizes six layers of laminated wood beams, with the wood beams 1 divided into a first layer (1 sheet), a standard layer (4 sheets), and a bottom layer (1 sheet). The specific placement of the hook-and-loop fasteners 2 is as follows: the hook surface 202 of the hook-and-loop fastener is affixed to the bottom surface of the first layer wood beam 1; the rough surface 201 of the hook-and-loop fastener is affixed to the top surface of the standard layer wood beam 1, and the hook surface 202 of the hook-and-loop fastener is affixed to the bottom surface; and the rough surface 201 of the hook-and-loop fastener is affixed to the top surface of the bottom layer wood beam 1. Effective epoxy resin glue is used to secure the wood beams 1 and the hook-and-loop fasteners 2 to prevent slippage.

[0039] The assembly and connection of wooden beams is carried out according to the following process. First, the wooden beam pieces are aligned and bonded. Figure 4 As shown, the six-layer wooden beam pieces 1 bonded with the parent-child hook and loop fasteners 2 are connected in the order of the first layer, the standard layer and the bottom layer by the matte surface 201 of the parent-child hook and loop fasteners and the hook surface 202 of the parent-child hook and loop fasteners to form a Figure 5 Next, the closing plate 3 and the superposition of the wooden beam pieces are aligned and bonded. The closing plate 3 is aligned to the cross section of the wooden beam, and the closing plate 3 and the superposition of the wooden beam pieces are bonded to form a Figure 6 Finally, the FRP composite material 4 is formed into a wood beam hoop. The FRP composite material 4 is evenly spaced along the axial direction of the wood beam, tightly holding the laminated body of the wood beam pieces. By using an effective epoxy resin glue, the FRP composite material 4 is bonded around the wood beam to form a wood beam hoop, and finally a variable stiffness wood beam structure proposed by the present invention is formed. Figure 7 shown.

[0040] To illustrate the advantages of the variable stiffness timber beam structure proposed in the present invention, the bending stiffness difference between the variable stiffness timber beam formed by stacking 6 layers of timber beams and the unlayered beam in this specific embodiment is calculated under the extreme complete slip condition. The cross-sectional schematic diagram is shown in FIG. Figure 8 shown.

[0041] For a variable stiffness timber beam formed by stacking 6 layers of timber beam sheets, the cross-sectional diagram is as follows: Figure 8 As shown in (a), the calculation formula for the cross-sectional inertia moment of each layer is:

[0042]

[0043] The overall bending stiffness is:

[0044]

[0045] For a non-layered whole beam, the cross-sectional diagram is as follows Figure 8 As shown in (b), the calculation formula for its section inertia moment is:

[0046]

[0047] The bending stiffness is:

[0048]

[0049] Comparison of the bending stiffness of the two are:

[0050]

[0051] As can be seen, under extreme complete slip conditions, the ratio of the bending stiffness of a variable-stiffness beam formed by stacking six layers of timber beams to that of a non-layered beam is 1 / 36. Therefore, by selecting the number of stacked layers n, the beam's stiffness reduction level can be varied, giving it the property of variable stiffness.

[0052] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A variable stiffness wooden beam, characterized in that: include: Wooden beam pieces, the wooden beam pieces are stacked by bonding with hook and loop fasteners; Closing plates, the closing plates are symmetrically arranged on both sides of the wooden beam pieces; the superimposed body of the wooden beam pieces is connected to the closing plates; An FRP composite material, wherein the FRP composite material tightly embraces the laminated body of the wood beam sheets; Under a major earthquake, the FRP composite material and the end caps deform and fail, and the Velcro straps slip, causing the combined effect between the layers to fail, reducing the stiffness of the composite beam. This allows it to adapt to the large deformation requirements under a major earthquake without causing breakage of the wooden beams or nodes.

2. The variable stiffness wooden beam according to claim 1, characterized in that: Among the two adjacent wooden beam pieces, one wooden beam piece is installed with the hairy surface of the parent-child hook and loop fastener, and the other wooden beam piece is installed with the hook surface of the parent-child hook and loop fastener; the hairy surface of the parent-child hook and loop fastener is connected with the hook surface of the parent-child hook and loop fastener in position.

3. The variable stiffness wooden beam according to claim 1, characterized in that: The size of the wooden beam piece is limited to a height-to-width ratio of less than or equal to 0.

3.

4. The variable stiffness wooden beam according to claim 1, characterized in that: The FRP composite material is distributed at equal intervals on the composite body of the wood beam sheets.

5. The variable stiffness wooden beam according to claim 1, characterized in that: The wooden beam pieces are all bonded to the parent-child hook and loop fasteners, the sealing plate and the FRP composite material by epoxy resin glue.

6. A building structure, characterized in that The method is constructed by using a variable stiffness wooden beam as claimed in any one of claims 1 to 5.

7. A method for preparing a variable stiffness wooden beam according to any one of claims 1 to 5, characterized in that: The following steps are involved: The hook side and the hair side of the parent-child hook and loop fastener are respectively adhered to both sides of the wooden beam piece; wherein the wooden beam pieces of the first layer and the bottom layer are only adhered to the hook side or the hair side of the parent-child hook and loop fastener adhered to the adjacent layer; The wooden beam pieces are bonded and overlapped by means of the hook surface and the hair surface of the parent-child hook and loop fastener; and the sealing plates are bonded to both sides of the overlapped body of the wooden beam pieces; The FRP composite material is tightly embraced by the superposition body of the wood beam pieces, and the FRP composite material and the superposition body of the wood beam pieces are bonded.

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