Wood-steel composite members and methods for manufacturing wood-steel composite members

Abstract

To obtain a wooden steel composite member, which allows a steel member and a wooden member to adequately bear a force in an axial direction, can be effectively manufactured, and suppresses buckling of the steel member without impairing the appearance thereof.SOLUTION: A wooden steel composite member comprises: a wooden member 1 having a solid cross-sectional shape; a plurality of steel members 2 that are disposed along an axial direction of the wooden member and dispersed on the periphery of the wooden member and assembled with the wooden member; and a member end member 3 that is fitted to both ends of the wooden member and the steel member so as to be capable of transmitting the force in the axial direction to both the wooden member and steel member. Grooves are formed in the axial direction in the wooden member, and a portion or whole of the cross section of the steel member is fitted into the groove. Buckling of the steel member is suppressed by restriction of the wooden member or the cross-sectional shape of the steel member. Tensile force can be introduced to the steel member and compression force can be introduced to the wooden member in advance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a structural member used for buildings and the like, which combines a wooden member and a member made of steel, and is a wood-steel composite member that mainly supports axial loads by both members.

Background Art

[0002] In order to effectively utilize forest resources, attempts have been made to make medium-scale or large-scale buildings, or mid-rise or high-rise buildings wooden. However, in mid-rise or high-rise buildings, a large axial force acts on columns and the like, and when a large axial force is supported by a wooden member, the cross-section tends to become excessively large. For this reason, for example, in Patent Document 1, Patent Document 2, and Patent Document 3, it has been proposed to combine a wooden member with a steel member and use it as a composite member.

[0003] Patent Document 1 proposes a composite column in which a steel member having an H-shaped cross-section is surrounded by a wooden member, and a composite column in which a steel member having a cross-shaped cross-section formed by combining H-shaped steels is surrounded by a wooden member. Further, Patent Document 2 proposes a composite column in which a square steel pipe is surrounded by a wooden member. Patent Document 3 discloses a column in which a steel member is arranged along the periphery of a rectangular wooden member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The composite columns proposed in Patent Documents 1 and 2 involve surrounding a steel member with a wooden member. This requires dividing the wooden member into multiple sections according to the shape of the steel member, processing them, and then adhesively joining these wooden members to surround the steel member. Consequently, the manufacturing process is not very efficient. Furthermore, in the composite column proposed in Patent Document 3, a single rectangular cross-section wooden member can be used, but each of the multiple members arranged around the perimeter has a small cross-section, making the steel members prone to buckling on their own. It has been proposed to connect each of the steel members to each other to suppress buckling, but if the steel members are connected laterally or diagonally at the outer perimeter, the appearance is significantly impaired when the composite member is used as a column. In addition, the steel members protrude from the outer surface of the wooden member, and when used as a column where the wooden member is visible on the outer surface, the steel members detract from the appearance.

[0006] On the other hand, in composite members combining steel and wood members, it is desirable that the load is appropriately distributed to both members from the initial stage of axial force application, and that the load is distributed nearly evenly within the wood member without being concentrated in any particular area. Therefore, there is a need for an end structure that ensures the load is reliably distributed to both the steel and wood members.

[0007] This invention has been made in view of the above circumstances, and its object is to provide a wood-steel composite member that can be manufactured efficiently and can suppress buckling of steel members without impairing their appearance. In addition, it is also intended to provide a wood-steel composite member in which axial force is appropriately applied to the steel member and the wood member. [Means for solving the problem]

[0008] To solve the above problems, the invention according to claim 1 provides a wood-steel composite member comprising: a wood-based member with a solid cross-sectional shape; a plurality of steel members provided along the axial direction of the wood-based member and distributed on the outer circumference of the wood-based member to be combined with the wood-based member; and end members attached to both ends of the wood-based member and the steel members, which are capable of transmitting axial force to both the wood-based member and the steel members, wherein a groove is formed in the axial direction of the wood-based member, and a part or all of the cross-section of the steel member is fitted into the groove, and the end member comprises a first steel plate that abuts against the end face of the wood-based member, a second steel plate arranged parallel to the first steel plate at a distance from it, and a connecting member that connects the first steel plate and the second steel plate, and the steel member is continuous from a position along the wood-based member beyond a notch or opening provided in the first steel plate and joined to the second steel plate or the connecting member by welding or bolting.

[0009] In this wood-steel composite member, the external force acting in the axial direction of the member acts on both the wood member and the steel member from the end member, and the external force is supported by both members. The wood member can be made of a single piece of wood or laminated wood, and can be pre-formed as a single unit before being combined with the steel member. Therefore, processing such as bonding the wood material when combining it with the steel member is unnecessary, enabling efficient work and allowing the wood member to be made into a strong, integrated member. Furthermore, by distributing the steel members around the outer periphery of the wooden members, the rigid steel members are located on the outer periphery of the cross-section, resulting in a member with high bending rigidity. Additionally, by fitting the steel members into grooves formed in the wooden members, the protrusion of the steel members from the sides of the composite member is avoided, resulting in a more aesthetically pleasing appearance. Furthermore, by fitting the steel member into a groove formed in the wood member, the steel member is constrained by the wood member, preventing buckling of the steel member in the direction along the side of the wood member and in the direction toward the center of the wood member. In addition, the bending rigidity of the steel member away from the wood member can be increased by adjusting the depth of the groove. This makes it possible to reduce the slenderness ratio of the steel member in the direction away from the wood member, thereby suppressing buckling of the steel member away from the wood member without compromising the appearance of the member.

[0010] Furthermore, this wood-steel composite member effectively suppresses buckling in all directions, including buckling away from the wood member, and allows the wood member to be effectively used as part of the structural member when combined with the wood member without increasing the cross-sectional area of ​​the steel member.

[0011] By setting the slenderness ratio of the steel member to the timber member's buckling resistance in the direction away from the timber member to be smaller than the critical slenderness ratio, buckling will not occur when the compressive stress of the steel member is within the elastic range. Furthermore, buckling of the steel member is suppressed in other directions by the timber member's restraint. Therefore, as long as the compressive stress generated in the steel member is kept within the elastic range, the structure can be designed with a steel member that will not buckle.

[0012] Furthermore, in this wood-steel composite member, the end face of the wood member is abutted against the first steel plate so that axial force is transmitted, while the second steel plate maintains a flat surface for joining with other structural members and can be provided with bolt insertion holes. This facilitates joining with other structural members. In addition, the space between the first and second steel plates can be used to reliably and easily join the end member of the wood material to the steel member fitted into the wood member.

[0013] The invention according to claim 2 provides a wood-steel composite member comprising: a wood-based member with a solid cross-sectional shape; a plurality of steel members provided along the axial direction of the wood-based member and distributed on the outer circumference of the wood-based member to be combined with the wood-based member; and end members attached to both ends of the wood-based member and the steel members, which are capable of transmitting axial force to both the wood-based member and the steel members, wherein a groove is formed in the axial direction of the wood-based member, and a part or all of the cross-section of the steel member is fitted into the groove, and the end member comprises a first steel plate that abuts against the end face of the wood-based member, a second steel plate arranged parallel to the first steel plate at a distance from it, and a connecting member that joins the first steel plate and the second steel plate, and the end face of the steel member abuts against the first steel plate and is joined to the first steel plate by a bolt that penetrates the first steel plate.

[0014] In this wood-steel composite member, the space between the first steel plate and the second steel plate can be used to fasten a bolt that penetrates the first steel plate. This makes it easy to join the steel member and the end member of the wood. Furthermore, by adjusting the length of the wood member to be longer than the steel member by a predetermined length, compressive force can be introduced into the wood member and tensile force into the steel member by the force of tightening the bolt.

[0015] The invention according to claim 3 is a wood-steel composite member according to claim 1 or claim 2, wherein the end member is pressed against the end face of the wood member, a compressive force is introduced in the axial direction of the wood member, the steel member is joined to the end member with a tensile force introduced, and the joining of the steel member and the end member is such that the tensile force acting on the steel member is reduced by the compressive force acting on the end member, and a compressive force is introduced after the tensile force has disappeared.

[0016] In this wood-steel composite member, the end member is pressed against the end face of the wood member, preventing deformation from progressing while the compressive force acting on the wood member remains small in the initial stages when an external axial force is applied. Furthermore, uneven distribution of axial compressive force within the wood member is avoided. Therefore, force can be transmitted from the end member to almost the entire length of the wood member, making it a member that resists external forces from the initial stages of axial application by both the wood and steel members. Additionally, by adjusting the proportion of the external axial force borne by the wood member, which has a smaller elastic modulus than the steel member, it becomes possible to effectively utilize the cross-section of the wood member to create a member with a high load-bearing capacity.

[0017] The invention according to claim 4 provides a method for manufacturing a wood-steel composite member, comprising the steps of: cutting a plurality of axial grooves into the outer circumference of a solid cross-sectional wood member; fitting a steel member continuous with the axial direction of the wood member into the grooves; contacting end members with material ends with both end faces of the wood member and introducing an axial compressive force to the wood member via the material ends; joining the material ends and the steel member in such a state that both axial tensile and compressive forces can be transmitted from the material ends to the steel member, while a compressive force has been introduced to the wood member and no axial force is acting on the steel member; and removing the force applied to the material ends that introduced the compressive force to the wood member.

[0018] This method allows for the secure joining of end members to a composite member, which is formed by fitting steel members around a integrally molded wooden member, so that axial forces are transmitted to both the steel and wooden members. Furthermore, by introducing compressive force to the wooden member and tensile force to the steel member, a composite member with high load-bearing capacity can be obtained.

[0019] The invention according to claim 5 includes a step of cutting a plurality of grooves in the axial direction on the outer peripheral portion of a solid cross-sectional wooden member, a step of fitting a steel member continuous in the axial direction of the wooden member into the grooves, a step of abutting a material end member against both end faces of the wooden member and introducing an axial compressive force into the wooden member through the material end member, and a step of joining the material end member and the steel member in a state where a compressive force is introduced into the wooden member so that either an axial tensile force or a compressive force can be transmitted from the material end member to the steel member. The step of introducing a compressive force into the wooden member loads a reaction force on the wooden member through the material end member and pulls the steel member. The step of joining the material end member and the steel member joins the material end member and the steel member in a state where a compressive force is introduced into the wooden member by the reaction force generated by pulling the steel member, and provides a method for manufacturing a wood-steel composite member.

[0020] In this method, it becomes possible to join the steel member and the material end member with a simple facility while a compressive force is introduced into the wooden member and a tensile force is introduced into the steel member.

Advantages of the Invention

[0021] As described above, in the wood-steel composite member of the present invention, it can be efficiently manufactured, the axial force is appropriately loaded on the steel member and the wooden member, and it is possible to suppress the buckling of the steel member without impairing the appearance. Further, in the method for manufacturing the wood-steel composite member of the present invention, it is possible to obtain a wood-steel composite member having a large load-bearing capacity by effectively utilizing the load-bearing capacity of the wooden member.

Brief Description of the Drawings

[0022] [Figure 1] It is a side view, an enlarged plan view, and an enlarged cross-sectional view of a wood-steel composite member which is an embodiment of the present invention. [Figure 2] It is a perspective view showing the structure of the end portion of the wood-steel composite member shown in FIG. 1. [Figure 3] It is an assembly view of the wood-steel composite member shown in FIG. 1. [Figure 4]This is a schematic diagram illustrating a means to prevent buckling of the steel member of the wood-steel composite member shown in Figure 1. [Figure 5] This is a schematic cross-sectional view showing another example of a means to prevent the steel member of the wood-steel composite member shown in Figure 1 from buckling. [Figure 6] Figure 1 is a schematic diagram showing a method of joining a steel member to a wood-steel composite member while applying compressive force to the wood member. [Figure 7] This diagram illustrates the axial load-bearing capacity of a wood-steel composite member in which compressive force is applied to the wood member and tensile force is applied to the steel member. [Figure 8] This is a schematic side view showing a joint structure between a steel member and a wood end member of a wood-steel composite member, which is another embodiment of the present invention. [Figure 9] This is a cross-sectional view showing another embodiment of the present invention, an example of a wood-steel composite member in which the cross-sectional shape of the steel member has been changed. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows a side view, an enlarged plan view, and an enlarged cross-sectional view of a wood-steel composite member, which is one embodiment of the present invention and is used as a column. Figure 2 is a perspective view from below showing the upper end of this wood-steel composite column. Figure 3 is a schematic perspective view showing how the wood member, steel member, and end plate (end member) of the same wood-steel composite column are joined together. This wood-steel composite column is primarily composed of a solid wooden member 1 with a nearly square cross-section, multiple steel members 2 fitted into axial grooves 11 formed on the side surface of the wooden member 1, and end plates 3 joined to both ends of the wooden member 1 and the steel members 2, enabling the transmission of axial forces to both the wooden member 1 and the steel members 2.

[0024] The wooden member 1 is made of laminated timber, which is formed by bonding together multiple pieces of wood with small cross-sections, and is capable of bearing axial forces as part of the structure. Alternatively, it may be made from single pieces of wood cut from logs. Approximately in the center of each of the four sides of the wooden member 1, an axial groove 11 is formed along its entire length. This groove 11 corresponds to the cross-sectional shape of the steel member 2 and is formed so that the steel member 2 can be fitted into it snugly.

[0025] The steel member 2 can be made of structural steel and is cut into strips from a steel plate. The steel member 2 is fitted into the four grooves formed in the wood member 1 such that the narrower side surface, i.e., the surface in the thickness direction of the steel plate, is parallel to the side surface of the wood member 1, and the wider side surface is in the depth direction of the groove 11 formed in the wood member 1. The narrower side surface of the steel member 2 is almost flush with the side surface of the wood member 1. The steel member 2 is longer than the wooden member 1 and protrudes from the end face of the wooden member 1, as shown in Figure 3, to which the end plate 3 is joined.

[0026] The end plate 3 comprises a first steel plate 31 that abuts against the end face of the wood member 1, a second steel plate 32 that is spaced apart from and parallel to the first steel plate 31, and a connecting member 33 that connects the first steel plate 31 and the second steel plate 32. The first steel plate 31 is made of a rectangular plate material that is approximately the same as the cross-sectional dimensions of the wooden member 1, and a rectangular notch 34 is provided at a position corresponding to the steel member 2 fitted into the groove 11 of the wooden member 1. The steel member 2 is inserted into the notch and protrudes beyond the position where the first steel plate 31 is provided towards the second steel plate 32.

[0027] The second steel plate 32 is rectangular in shape and larger than the first steel plate 31, and is provided with multiple through holes 35 for inserting bolts to connect it to other structural members. The connecting member 33 is a tubular member with a rectangular cross-section made of steel, and is used to connect the first steel plate 31 and the second steel plate 32 in parallel. The connection with the first steel plate 31 and the connection with the second steel plate 32 are made by welding.

[0028] The above-mentioned wooden member 1, steel member 2, and end plate 3 can be assembled as shown in Figure 3. As shown in Figure 3(a), the steel member 2 is fitted into grooves 11 formed on each of the four sides. At this time, the steel member 2 protrudes from the end face of the wood member 1, and the end plate 3 is brought into contact with the end face of the wood member 1 by fitting the steel member 2 into the notch 34 of the first steel plate 31 as shown in Figure 3(b). At this time, a resin that hardens later may be applied to prevent a gap from forming between the end face of the wood member 1 and the first steel plate 31. Then, the end of the steel member 2 is welded to the second steel plate 32 of the end plate 3 in a state where axial force can be transmitted from the first steel plate 31 to the wood member 1. With this joining, when an axial force is applied to the wood-steel composite column, the axial force is applied to both the steel member 2 and the wood member 1 from the initial state, and the composite member appropriately supports the load. In other words, in the initial state when the load is applied, it is avoided that only the steel member 2 will bear the load and the load supported by the wood member 1 will be reduced.

[0029] Furthermore, in a wood-steel composite column where a wood member 1 and a steel member 2 are combined as described above, buckling of the steel member 2 in the direction parallel to the side surface of the wood member 1 (directions of arrows A and B in Figure 1(d)) and buckling in the direction toward the center of the wood member 1 (direction of arrow C in Figure 1(d)) is suppressed by the constraint of the wood member 1. Buckling in the direction away from the wood member 1 by slipping out of the groove of the wood member 1 (direction of arrow D in Figure 1(d)) is less likely to occur by setting the bending stiffness of the steel member 2 in the direction away from the wood member 1 to be greater than the bending stiffness in the direction along the side surface of the wood member 1. In other words, even with the same cross-sectional area, the slenderness ratio of the steel member 2 with respect to buckling in the direction away from the wood member 1 becomes smaller. In addition, the bending stiffness of the steel member 2 in the direction away from the wood member 1 can be increased by increasing the depth of the groove 11, and it is possible to reduce the slenderness ratio. In particular, by setting the slenderness ratio of the steel member 2 to the buckling direction away from the wood member 1 to be smaller than the critical slenderness ratio, buckling of the steel member 2 will not occur when the compressive stress generated in the wood-steel composite column is kept within the elastic range.

[0030] On the other hand, if the depth of the steel member 2 being fitted into the wood member 1 is increased in order to reduce the slenderness ratio of the steel member 2 in the direction away from the wood member 1, the two grooves cut from adjacent sides of the wood member 1 will move closer to the center of the wood member 1, and the distance between the two grooves will decrease. As a result, as shown in Figure 4, the two steel members 2a and 2b fitted into the two grooves, and a part 1a of the wood member adjacent to these steel members (the shaded area shown in Figure 4), may buckle in the direction away from the center of the wood member 1, accompanied by splitting. In contrast, when the two steel members 2a and 2b buckle, the resultant force Pt of the forces Pe acting from the steel members 2a and 2b on the wood member 1a is smaller than the splitting strength Rw along the line segment L connecting the positions where the two grooves are closest, then the above buckling will not occur.

[0031] In other words, the above buckling is suppressed by satisfying the requirements of the following equation. Pt <Rw ········ (1) The above Pt can be estimated by the following formula, based on "Chapter 3 Buckling-Restrained Braces" (3.3.4) of the "Guidelines for Vibration Control Design of Steel Structures" (Architectural Institute of Japan). Pt =√2·Pe ·········· (2) Pe =(4·Nmax·s) / ln ··· (3) Here, Nmax: the maximum axial force acting on a single steel member. s: Maximum gap between the groove and the steel member (groove width - steel member width) ln: Wavelength of local buckling Furthermore, the above-mentioned splitting strength Rw may vary depending on various conditions such as the material of the timber member, but it can be estimated from experimental results, or based on "6. Design of Joints" (602.1.3) of the "Design Standards for Timber Structures" (Architectural Institute of Japan), using the following formula. Rw =2·Cr·L·√he ····· (4) Here, Cr: splitting fracture constant L: Shear resistance length he: Distance from the edge of the load-bearing material to the far end of the cross-section of the steel member. Therefore, by setting the shape and dimensions of the groove 11 such that the splitting strength Rw is greater than the resultant force Pt, it is possible to prevent the buckling of the two steel members 2a and 2b and a part 1a of the wood member.

[0032] Furthermore, if buckling cannot be reliably prevented by setting the cross-sectional shape of the steel member 2 or the shape and dimensions of the groove as described above, buckling can also be prevented by fastening the steel member 2 to the wooden member 1. For example, as shown in Figure 5(a), screw holes can be provided in the steel member 1, and the steel member 2 can be fastened to the wooden member 1 by screws 21 or lag screws that pass through the steel member 2 and are screwed into the wooden member 1. Alternatively, as shown in Figure 5(b), horizontal holes can be drilled along each side of the wooden member 1, penetrating it horizontally, and through holes can be provided in the steel member 2, which is fitted into the groove, at positions corresponding to the horizontal holes. The steel member 2 can then be fastened to prevent it from coming out of the groove in the wooden member 1 by drift pins 22 inserted from the horizontal holes into the through holes in the steel member. In addition, bolts can be used instead of the drift pins 22, and the steel member 2 can also be prevented from coming out of the groove in the wooden member 1 by using a steel belt wrapped around the wooden member, or a steel belt fastened to the wooden member to hold the steel member in place.

[0033] The above-described wood-steel composite column may be constructed in which both the wood member 1 and the steel member 2 are joined to the end plate 3 while both are under virtually no stress in the axial direction, but it is also possible to construct a column in which the end plate 3 is joined while compressive force is applied to the wood member 1 and tensile force is applied to the steel member 2. As a method for joining the end plates 3 with compressive force applied to the wood member 1 and tensile force applied to the steel member 2, the following method can be employed.

[0034] In the method shown in Figure 6(a), two end plates 3 are brought into contact with both end faces of the wooden member 1, and an external force is applied to the end plates 3 at both ends, pressing them against the end faces of the wooden member 1. This introduces an axial compressive force to the wooden member 1. At this time, the end plates 3 and the steel member 2 are not connected, and a gap equivalent to the amount of deformation caused by the compressive force introduced to the wooden member 1 is provided between the second steel plate 32 of the end plate 3 and the end face of the steel member 2. Then, while maintaining the state in which a compressive force is acting on the wooden member 1, the steel member 2 and the second steel plate 32 are joined by welding W1. After the welding is completed, the external force is removed, introducing a tensile force to the steel member 2, which balances the compressive force of the wooden member 1. In the wood-steel composite column shown in Figure 1, the steel member 2 is welded to the second steel plate 32. However, if the heat from welding does not damage the wood member, the first steel plate 31 can also be welded to the steel member 2 around the notch.

[0035] The above-mentioned external force can be applied by installing two reaction blocks as a fixed structure in the wood-steel composite column's manufacturing yard, and applying a reaction force to these reaction blocks to press the end plates 3 against both ends of the wood member 1. Alternatively, two reaction plates can be installed at both ends of the wood-steel composite column, facing the end plates 3, and these reaction plates can be connected by tension members, applying a reaction force to the reaction plates to press the end plates against the wood member.

[0036] In the method shown in Figure 6(b), a reaction plate 41 is installed facing the second steel plate 32 of the end plate 3, and connected to a steel member 2 that extends through an opening in the second steel plate 32. A jack 42 is then interposed between the reaction plate 41 and the end plate 3 to press the end plate 3 against the end face of the wood member 1 while applying a reaction force to the steel member 2. This introduces a compressive force to the wood member 1 and a tensile force to the steel member 2. In this state, the second steel plate 32 of the end plate 3 and the steel member 2 are joined by welding W2. After that, the portion of the steel member 2 protruding from the second steel plate 32 is cut off. Alternatively, instead of the jack 42 that presses the end plate 3 against the wood member 1, a large-diameter bolt can be used, and the end plate 3 can be pressed against the wood member 1 by the force of screwing it in.

[0037] When pressing the end plates against the end face of the wood member using the method shown in Figures 6(a) and 6(b), both end plates 3 may be pressed against both ends of the wood member 1 while the ends of the steel member 2 are not yet joined to the end plates 3. Alternatively, one end plate may be joined to the steel member in advance, and the other end plate may be pressed against the end face of the wood member to introduce compressive force to the wood member. Then, with compressive force introduced to the wood member, the steel member is joined to the other end plate.

[0038] As described above, in a wood-steel composite column in which compressive force is introduced to the wood member 1 and tensile force is introduced to the steel member 2, the end plate 3 is joined to it, and as explained below, the load-bearing capacity of the wood member 1 can be effectively utilized to support a large load, resulting in a wood-steel composite column that can support a large load. In a wood-steel composite column where the end plate 3 is joined to the wood member 1 and steel member 2 without any axial force being applied to either, as shown in Figure 7(a), when an axial load is applied, axial force is applied to both members from the initial stage of load application. Since the end plate 3 maintains the same amount of strain in the wood member 1 and steel member 2, the axial force applied to each of the wood member 1 and steel member 2 is distributed according to the ratio of their axial stiffness. In other words, even if the load acting in the axial direction increases, the load is borne by the ratio of the axial stiffness EwAw of the wood member to the axial stiffness EsAs of the steel member. Here, Ew is the elastic modulus of the wood member, Aw is the cross-sectional area of ​​the wood member, Es is the elastic modulus of the steel member, and As is the cross-sectional area of ​​the steel member. As the axial load increases, the load can be supported until the compressive stress of either the wood member 1 or the steel member 2 reaches its allowable stress. As shown in Figure 7(a), generally, the strain εwa1 when the wood member reaches its allowable stress is greater than the strain εsa1 when the steel member reaches its allowable stress. Therefore, when the compressive stress of the steel member reaches its allowable stress, the steel member bears an axial force of Psa, and the compressive stress of the wood member has not yet reached its allowable stress, so the wood member bears an axial force of Pw1. This axial force Pw1 borne by the wood member is smaller than the axial force Pwa borne when the wood member reaches its allowable stress.

[0039] On the other hand, as shown in Figure 7(b), when the end plates are joined with a compressive force Pwo applied to the wood member and a tensile force Pso applied to the steel member, the compressive force of the wood member and the tensile force of the steel member are in equilibrium as internal forces, so Pwo = Pso. Then, when an axial force is applied as an external force, the axial force borne by each increases in proportion to the ratio of the axial stiffness EwAw of the wood member and the axial stiffness EsAs of the steel member. When the compressive stress of the steel member reaches the allowable stress, the steel member bears an axial force of Psa, and the wood member bears an axial force of Pw2. This axial force Pw2 borne by the wood member is greater than the axial force Pw1 when a load is applied from the stress-free state shown in Figure 7(a). Therefore, the wood-steel composite column can support an axial force of Psa + Pw2, and by joining the end plates with a compressive force applied to the wood member and a tensile force applied to the steel member, a wood-steel composite column with a large load-bearing capacity can be made.

[0040] In the wood-steel composite column of the embodiment described above, the steel member 2 is joined to the second steel plate 32 by welding its end face against it. However, the steel member can be joined to the end plate in other ways, for example, in the joining configuration shown in Figure 8. The wood-steel composite column shown in Figure 8(a) is constructed in the same way as the wood-steel composite columns shown in Figures 1 to 3, with a strip-shaped steel member 52 fitted into a groove formed on the side surface of a wood member 51. The end plate 53 has the same first steel plate 54, second steel plate 55, and connecting member 56 as the end plate used in the wood-steel composite columns shown in Figures 1 to 3, but in addition to these, it is equipped with four connecting plates 57 provided between the first steel plate 54 and the second steel plate 55. These connecting plates 57 are positioned along the end of the steel member 52 that protrudes through a notch in the first steel plate 54, and are welded to the first steel plate 54 and the second steel plate 55. The steel member 52 is then superimposed on these connecting plates 57 and joined by high-strength bolts 58 inserted through through holes provided at corresponding positions on both sides. Even with such wood-steel composite columns, the end plates 53 can be joined to the wood members 51 and the steel members 52 while applying compressive force to the wood members 51 and tensile force to the steel members 52, using the same methods as for the wood-steel composite columns shown in Figures 1 to 3.

[0041] In the wood-steel composite column shown in Figure 8(b), the wood member 61 and the steel member 62 have the same cross-sectional shape as the wood-steel composite columns shown in Figures 1 to 3, and the end plate 63 similarly has a first steel plate 64, a second steel plate 65, and a connecting member 66. In this wood-steel composite column, a flange portion 62a is provided at the end of the steel member 62, and this flange portion 62a abuts against the second steel plate 65 and is joined with bolts 67. Multiple bolt holes are provided in the flange portion 62a of the steel member 62, and female threads are formed in these bolt holes. The second steel plate 65 of the end plate 63 is provided with through holes at positions corresponding to the bolt holes of the abutted flange portion 62a, and the bolts 67 are inserted through these through holes, screwed into the bolt holes of the flange portion 62a, and joined by tightening. The steel member 62 can also be brought into contact with the second steel plate 65 by adjusting the length of the flange portion 62a so that it faces the second steel plate 65 with a predetermined gap while the first steel plate 64 of the end plate 63 is in contact with the end face of the wooden member 61, and then tightening the bolt 67. By joining the flange portion 62a to the second steel plate 65 in this way, tensile force can be introduced to the steel member 62 and compressive force can be introduced to the wooden member.

[0042] In the wood-steel composite column shown in Figure 8(c), the wood member 71 and the steel member 72 have the same cross-sectional shape as the wood-steel composite columns shown in Figures 1 to 3, and the end plate 73 similarly has a first steel plate 74, a second steel plate 75, and a connecting member 76. In this embodiment, the length of the steel member 72 is adjusted so that its end face faces the first steel plate 74 of the end plate 73. Bolt holes are formed axially from the end face, and female threads are cut into them. The first steel plate 74 of the end plate 73 has through holes at positions corresponding to the bolt holes provided on the end face of the steel member 72. The steel member 72 and the end plate 73 are joined by bolts 77 that are inserted through the through holes in the first steel plate 74 and screwed into the bolt holes provided on the end face of the steel member 72. Furthermore, in this wood-steel composite column, the length of the steel member 72 can be adjusted so that when the first steel plate 74 of the end plate 73 is brought into contact with the end face of the wood member 71, the end face of the steel member 72 and the first steel plate 74 face each other with a predetermined gap between them. The end face of the steel member 72 is then brought into contact with the first steel plate 74 by the force of tightening the bolt 77, and the steel member 72 and the end plate 73 can be joined while tensile force is introduced to the steel member 72 and compressive force to the wood member 71.

[0043] On the other hand, in the wood-steel composite column described above, a strip of steel plate is used as the steel member and fitted so that the wider side is in the depth direction of the groove provided in the wood member. However, steel members with other cross-sectional shapes can be used. For example, as shown in Figure 9(a), a steel member 82 can be used that has a flange portion 82a that is continuous in the axial direction along the surface of the wood member when fitted into the groove of the wood member 81, and has a T-shaped cross-section. By using such a cross-sectional shape, the bending rigidity and cross-sectional area of ​​the steel member 82 can be increased, making the steel member 82 less prone to buckling and resulting in a wood-steel composite column with a large load-bearing capacity. Furthermore, as shown in Figure 9(b), a steel member 92 having a rectangular cross-section with its longer side aligned with the side surface of the wooden member 91 can also be used. In such a wood-steel composite column, there is a risk that the steel member 92 may buckle away from the wooden member 91, but buckling of the steel member 92 can be suppressed by fastening the steel member 92 to the wooden member 91.

[0044] Furthermore, the present invention is not limited to the embodiments described above, and can be implemented with modifications within the scope of the present invention. For example, although the embodiments described above are all used as columns, they can also be used as members subjected to large axial forces, such as braces. Furthermore, in the embodiments described above, a steel end plate is used as the end member, but it is also possible to use a composite member of steel and other materials, such as a composite member of steel and concrete or mortar, or a member made of reinforced concrete, as the end member. [Explanation of Symbols]

[0045] 1: Wooden member, 2: Steel member, 3: End plate, 11: Grooves formed in wooden members, 21: Screw, 22: Drift pin, 31: First steel plate, 32: Second steel plate, 33: Connecting member, 34: Notch formed in the first steel plate, 35: Through hole for inserting a bolt, 41: Reaction plate, 42: Jack, 51: Wooden member, 52: Steel member, 53: End plate, 54: First steel plate, 55: Second steel plate, 56: Connecting member, 57: Connecting plate between the first steel plate and the second steel plate. 58: High-strength bolts, 61: Wooden member, 62: Steel member, 62a: Flange portion of the steel member, 63: End plate, 64: First steel plate, 65: Second steel plate, 66: Connecting member, 67: Bolt 71: Wooden member, 72: Steel member, 73: End plate, 74: First steel plate, 75: Second steel plate, 76: Connecting member, 77: Bolt 81: Wooden member, 82: Steel member, 82a: Flange portion provided along the axial direction of the steel member, 91: Wooden members, 92: Steel members,

Claims

1. A wooden member with a solid cross-section, Multiple steel members are provided along the axial direction of the wood member and are distributed around the outer circumference of the wood member, and are combined with the wood member. The wood member and the steel member are fitted with end members that are attached to both ends of the wood member and the steel member, and are capable of transmitting axial force to both the wood member and the steel member. The aforementioned wooden member has grooves formed in the axial direction. A part or all of the cross-section of the steel member is fitted into the groove. The end member comprises a first steel plate that abuts against the end face of the wood member, a second steel plate that is spaced parallel to the first steel plate and arranged at a distance from it, and a connecting member that joins the first steel plate and the second steel plate. The wood-steel composite member is characterized in that the steel member extends from a position along the wood member, through a notch or opening provided in the first steel plate, and is joined to the second steel plate or the connecting member by welding or bolts.

2. A wooden member with a solid cross-section, Multiple steel members are provided along the axial direction of the wood member and are distributed around the outer circumference of the wood member, and are combined with the wood member. The wood member and the steel member are fitted with end members that are attached to both ends of the wood member and the steel member, and are capable of transmitting axial force to both the wood member and the steel member. The aforementioned wooden member has grooves formed in the axial direction. A part or all of the cross-section of the steel member is fitted into the groove. The end member comprises a first steel plate that abuts against the end face of the wood member, a second steel plate that is spaced parallel to the first steel plate and arranged at a distance from it, and a connecting member that joins the first steel plate and the second steel plate. The wood-steel composite member is characterized in that the end face of the steel member abuts against the first steel plate and is joined to the first steel plate by bolts that penetrate the first steel plate.

3. The aforementioned end member is pressed against the end face of the wood member, A compressive force is introduced in the axial direction of the wooden member. The steel member is joined to the end member with tensile force applied to it. The wood-steel composite member according to claim 1 or 2, characterized in that the joining of the steel member and the end member is such that the tensile force acting on the steel member is reduced by a compressive force acting on the end member, and a compressive force is introduced after the tensile force has disappeared.

4. A process of cutting multiple grooves in the axial direction into the outer circumference of a solid cross-sectional wooden member, The process of fitting a steel member continuous with the axial direction of the wooden member into the groove, The process involves bringing end members into contact with both end faces of the aforementioned wooden member, and introducing an axial compressive force to the wooden member through the end members. A step of joining the end member and the steel member in such a way that both axial tensile and compressive forces can be transmitted from the end member to the steel member, while a compressive force is applied to the wood member and no axial force is acting on the steel member. A method for manufacturing a wood-steel composite member, characterized by including a step of applying a force to the end member of the material and removing the force that has introduced a compressive force to the wood member.

5. A process of cutting multiple grooves in the axial direction into the outer circumference of a solid cross-sectional wooden member, The process of fitting a steel member continuous with the axial direction of the wooden member into the groove, The process involves bringing end members into contact with both end faces of the aforementioned wooden member, and introducing an axial compressive force to the wooden member through the end members. The process includes joining the end member and the steel member in such a way that both axial tensile and compressive forces can be transmitted from the end member to the steel member, while a compressive force is applied to the wood member. The process of introducing compressive force to the wood member involves applying a reaction force to the wood member via the end member and tensing the steel member. A method for manufacturing a wood-steel composite member, characterized in that the step of joining the wood end member and the steel member is performed in a state in which a compressive force is introduced to the wood member by the reaction force caused by tensing the steel member.

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