Joint structure of wooden members

Abstract

To provide a joint structure of wooden members capable of firmly joining the wooden members to each other with a simple structure.SOLUTION: The wood member joining structure 1 joins a plurality of wood members 10A to 10C to each other. A through-hole 12 is formed in each of the wooden pieces 10A to 10C, a recess 13 is formed in a side 11A and a side 11B of each of the wooden pieces 10A to 10C that are in contact with each other, and a steel sheet 20 in which a through-hole 22 is formed is attached to a bottom 11C of the recess. The plurality of wood 10A and 10B are arranged so that the steel plates 20 abut on each other, and fixed by bolts 40 inserted into the through-holes 12 of the wood 10A and 10B and the through-holes 22 of the steel plates 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a joining structure for wooden members that joins a plurality of wooden members together. [Background technology]

[0002] BACKGROUND ART Joining structures for joining wooden members have been proposed in the past (see Patent Documents 1 to 3). Patent Document 1 shows a joint structure between a foundation and a pillar. A joint metal is fixed to the top surface of the foundation with screws, and this joint metal is housed in a housing on the underside of the pillar. Furthermore, drift pins pass through the pinholes in the pillar and the joint metal, and a liquid solidifying agent is poured into the gap in the housing.

[0003] Patent Document 2 shows a metal plate connector joining structure in which a metal plate connector having a plurality of claws formed by cutting and raising a metal plate at a plurality of predetermined locations is installed across the joint between the plates to join the plates. The claws are press-fitted near the joint between the plates, and the metal plate connector is adhered to the plates with an adhesive. Patent Document 3 shows a joint structure for wooden members in which wooden reinforcing members, namely, knee braces and tie bars, are provided at the corners where a pillar and a beam are joined. At the joints between the pillar and beam and the knee braces, multiple wooden dowels are inserted so as to penetrate the knee braces fitted with the pillar or beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-133093 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-241975 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-14155 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a joining structure for wooden members that is simple in structure but can firmly join wooden members together. [Means for solving the problem]

[0006] The first invention of the joining structure for wooden members (e.g., joining structure 1 for wooden members described below) is a joining structure for wooden members that joins multiple wooden members (e.g., wood pieces 10A to 10C described below), characterized in that each of the wooden members has a through hole (e.g., through hole 12 described below), a recess (e.g., recess 13 described below) is formed on the side surfaces of the wooden members that abut against each other (e.g., side surfaces 11A and 11B described below), a steel plate (e.g., steel plate 20 described below) with a through hole (e.g., through hole 22 described below) formed therein is attached to the bottom surface of the recess (e.g., bottom surface 11C of the recess described below), and the multiple wooden members are arranged so that the steel plates abut against each other and are fixed together with bolts (e.g., bolt 40 described below) inserted into the through holes of the wooden members and the through holes of the steel plates.

[0007] According to this invention, a steel plate is fixed to the bottom surfaces of the recesses of a plurality of wooden members, and the wooden members are arranged so that the steel plates abut against each other and fastened with bolts. Therefore, the tightening force applied to the bolt acts planarly on the bottom surfaces of the recesses of the wooden members via the steel plate, preventing the bolt from locally sinking into the wooden members. Furthermore, the tightening force applied to the bolt acts planarly on the wooden members via the steel plate, increasing the bearing rigidity and splitting strength of the wooden members. Therefore, the joining structure for wooden members of the present invention increases the rigidity and strength of the joints between the wooden members, allowing for a strong joining of the wooden members despite the simple structure.

[0008] The joining structure of wooden members of the second invention is characterized in that the depth of the recess is approximately the same as the thickness of the steel plate, and the surface of the steel plate is approximately flush with the abutting side surfaces of the wooden members.

[0009] According to this invention, the depth of the recess is approximately the same as the thickness of the steel plate, and the surface of the steel plate is approximately flush with the abutting sides of the wooden members, so that the sides of the wooden members can be joined without any gaps. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a joining structure for wooden members that is simple in structure but can firmly join wooden members together. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view of a wooden bridge to which a joint structure for wooden members according to a first embodiment of the present invention is applied. [Figure 2] This is an AA cross section of a wooden bridge. [Figure 3] FIG. 1 is a schematic cross-sectional view showing the joint structure of two wooden members in a wooden bridge. [Figure 4] 1A and 1B are a plan view and a cross-sectional view of a steel plate (with four screw holes) used in a joining structure for wooden members according to a first embodiment. [Figure 5] 1A and 1B are a plan view and a cross-sectional view of a steel plate (with eight screw holes) used in a joining structure for wooden members according to a first embodiment. [Figure 6] 1 is a diagram showing deformation of wood when a tensile force is applied to a conventional joint structure of wooden members. [Figure 7] FIG. 3 is a diagram showing the flow of force when a horizontal force (shear force) acts on the joint structure of wooden members of the first embodiment. [Figure 8] FIG. 5 is a cross-sectional view of a joining structure for wooden members according to a second embodiment of the present invention. [Figure 9] FIG. 1 is a diagram showing a list of test specimens used in a load test. [Figure 10] FIG. 10 is a diagram showing screws used in the test specimen. [Figure 11] FIG. 1 is a diagram showing a steel plate (type A) used in a test specimen. [Figure 12] FIG. 1 is a diagram showing a steel plate (type B) used in a test specimen. [Figure 13]FIG. 10 is a diagram showing a method for applying force to specimens No. 1 to No. 7 in which the joint direction is the fiber direction. [Figure 14] This figure shows how to apply force to the No. 8 and No. 9 specimens whose joint directions are perpendicular to each other. [Figure 15] FIG. 10 is a diagram showing the results of the load test on specimens No. 1 to No. 7. [Figure 16] FIG. 10 shows the results of the loading test on specimens No. 8 and No. 9. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the embodiments, the same components will be denoted by the same reference numerals, and the description thereof will be omitted or simplified. [First embodiment] Fig. 1 is a side view of a wooden bridge 1 to which a joint structure for wooden members according to a first embodiment of the present invention is applied, and Fig. 2 is a cross-sectional view of the wooden bridge 1 taken along line AA. The wooden bridge 1 is constructed by combining a plurality of pieces of timber 10 each having a predetermined length. For example, as shown by the dashed line B in Fig. 2, in the wooden bridge 1, the plurality of pieces of timber 10 are joined together at various points, including the ends.

[0013] FIG. 3 is a schematic cross-sectional view showing the joint structure of two wooden pieces 10A and 10B as wooden members in the wooden bridge 1. As shown in FIG. The wooden pieces 10A and 10B are members having a predetermined length and a rectangular cross section. Hereinafter, the two back-to-back side surfaces of each wooden piece 10A and 10B will be referred to as side surface 11A and side surface 11B. A through-hole 12 is formed in each wooden piece 10A and 10B, extending from side surface 11A to side surface 11B. A steel plate 20 is attached to the side surface 11A of the wooden pieces 10A and 10B with screws 21, which serve as rod-shaped fasteners. The base end surfaces of the screws 21 are substantially flush with the surface of the steel plate 20. The steel plate 20 has through holes 22 formed therein that communicate with the through holes 12 in the wooden pieces 10A and 10B. As shown in FIGS. 4 and 5, four or eight screw holes 23 for inserting the screws 21 are formed at equal intervals around the through holes 22 in the steel plate 20.

[0014] The wooden pieces 10A and 10B are arranged so that the steel plates 20 abut against each other, and a support plate 30 is arranged on the side surface 11B of the wooden pieces 10A and 10B. The support plate 30 has a through hole 31 formed therein that communicates with the through hole 12 of the wooden pieces 10A and 10B. The wooden pieces 10A and 10B are fixed to each other by inserting bolts 40 through the through holes 31 of the support plate 30, the through holes 12 of the wooden pieces 10A and 10B, and the through holes 22 of the steel plate 20, and tightening nuts 41 onto the bolts 40.

[0015] Conventionally, as shown in Fig. 6, no steel plates are provided on the side surfaces of the wooden pieces 110A and 110B. In this case, when a shear force P (indicated by the hollow arrow in Fig. 6) acts on the wooden pieces 110A and 110B, the bolts 140 joining the wooden pieces 110A and 110B to each other press against the inner wall surfaces of the through holes 112 of the wooden pieces 110A and 110B, causing bearing deformation in which the bolts 140 locally sink into the wooden pieces 110A and 110B, as shown by the diagonal lines in Fig. 6. In contrast, in the present invention, steel plates 20 are provided on the side surfaces 11A of the wooden pieces 10A and 10B. Therefore, when a single-plane shear force P (indicated by the hollow arrow in FIG. 3) acts on the wooden pieces 10A and 10B, the bolts 40 joining the wooden pieces 10A and 10B press the inner wall surfaces of the through holes 22 of the steel plates 20 with a pressing force P1, as shown in FIG. 7. This pressing force P1 then acts as a shear force P2 on the joint surfaces S between the steel plates 20 and the wooden pieces 10A and 10B, preventing the bolts 40 from locally sinking into the wooden pieces 10A and 10B.

[0016] According to this embodiment, the following effects are obtained. (1) Steel plates 20 are fixed to the side surfaces 11A of a plurality of wooden pieces 10A, 10B, and the steel plates 20 of these wooden pieces 10A, 10B are arranged so that they abut against each other, and the wooden pieces 10A, 10B are fastened to each other with bolts 40 and nuts 41. Therefore, the tightening force applied to the bolts 40 acts on the wooden pieces 10A, 10B in a planar manner via the steel plates 20, preventing the bolts 40 from locally embedding into the wooden pieces 10A, 10B. Furthermore, the tightening force applied to the bolts 40 acts on the wooden pieces 10A, 10B in a planar manner via the steel plates 20, thereby increasing the bearing rigidity and splitting strength of the wooden pieces 10A, 10B. Therefore, the joining structure for wooden members of the present invention increases the rigidity and strength of the joint between the wooden pieces 10A, 10B, allowing the wooden pieces 10A, 10B to be firmly joined to each other despite the simple structure. In addition, the stiffening effect of the steel plate 20 can be adjusted by adjusting the adhesive area between the side surface 11A of the wooden members 10A and 10B and the steel plate 20, and the number of screws 21 driven from the steel plate 20 into the wooden members 10A and 10B, and the rigidity and strength of the joints between the wooden members 10A and 10B can also be adjusted.

[0017] (2) Since the steel plate 20 is fixed to the wooden pieces 10A and 10B with the screws 21, the shear resistance cross-sectional area is increased by the screws 21 driven into the wooden pieces 10A and 10B, and therefore the shear rigidity and splitting strength of the wooden pieces 10A and 10B are increased, thereby increasing the bonding strength between the wooden pieces 10A and 10B. (3) The base end faces of the screws 21 driven into the steel plates 20 are made substantially flush with the surfaces of the steel plates 20, so that the steel plates 20 of the wooden pieces 10A and 10B can be joined together without any gaps, ensuring reliable surface contact.

[0018] (4) In this embodiment, the side surfaces 11A of the wooden pieces 10A and 10B are not provided with countersunk recesses 13 (see FIG. 8 ) for receiving the steel plates 20, and the wooden pieces 10A and 10B are arranged with the steel plates 20 abutting against each other. Therefore, the facing wooden pieces 10A and 10B do not abut directly against each other, and the steel plates 20 are interposed between the wooden pieces 10A and 10B. Therefore, even when the joined structure for wooden members of this embodiment is installed outdoors, rainwater does not accumulate at the joint between the wooden pieces 10A and 10B. Furthermore, because the side surfaces 11A of the wooden pieces 10A and 10B are not provided with countersunk recesses, the penetration of rainwater into the wooden pieces 10A and 10B is reduced. This increases the durability of the joint between the wooden pieces 10A and 10B.

[0019] Second Embodiment FIG. 8 is a cross-sectional view of a joint structure 1A for wooden members according to a second embodiment of the present invention. In this embodiment, three pieces of wood 10A, 10B, and 10C are joined together. The wooden piece 10C is a member having a predetermined length and a rectangular cross section. The wooden piece 10C has a through-hole 12 formed therein, which extends from the side surface 11A to the side surface 11B. A recess 13 is formed at the end of the through-hole 12 on the side surfaces 11A and 11B of the wooden piece 10C. A steel plate 20 is placed in the recess 13 of the wooden piece 10C and attached with screws 21. As a result, the surface of the steel plate 20 is substantially flush with the side surface 11A of the wooden piece 10C. A through hole 22 is formed in the steel plate 20, which communicates with the through hole 12 of the wooden piece 10C.

[0020] A recess 13 is formed on the side surface 11A of the wooden pieces 10A and 10B at the end of the through hole 12, and the steel plate 20 is housed in this recess 13. As a result, the steel plate 20 is placed on the bottom surface 11C of the recess 13, and the surface of the steel plate 20 is flush with the side surface 11A of the wooden pieces 10A and 10B. A recess 14 in which a bearing plate 30 is disposed is formed at the end of the through-hole 12 in the side surface 11B of the wooden pieces 10A and 10B.

[0021] The wooden pieces 10A and 10B are arranged with the wooden piece 10C sandwiched between them so that the steel plates 20 of the wooden pieces 10A, 10B, and 10C abut against each other. Furthermore, a support plate 30 is placed in the recess 14 on the side surface 11B of the wooden pieces 10A and 10B. This support plate 30 has a through hole 31 formed therein that communicates with the through hole 12 of the wooden pieces 10A and 10B. The wooden pieces 10A to 10C are fixed to one another by inserting bolts 40 through the through holes 31 of the support plate 30, the through holes 12 of the wooden pieces 10A to 10C, and the through holes 22 of the steel plate 20, and tightening nuts 41 onto the bolts 40. In this embodiment, as shown in FIG. 8, a double shear force P (indicated by an outline arrow in FIG. 8) acts. According to this embodiment, in addition to the above-mentioned (2), the following effect is obtained. (5) Steel plates 20 are fixed to the recesses 13 of multiple wooden pieces 10A-10C, and the steel plates 20 of these wooden pieces 10A-10C are arranged so that they abut against each other, and the wooden pieces 10A-10C are fastened together with bolts 40 and nuts 41. Therefore, the tightening force applied to the bolts 40 acts planarly on the bottom surfaces 11C of the recesses of the wooden pieces 10A-10C via the steel plates 20, preventing the bolts 40 from locally embedding into the wooden pieces 10A, 10B. Furthermore, the tightening force applied to the bolts 40 acts planarly on the wooden pieces 10A-10C via the steel plates 20, thereby increasing the bearing rigidity and splitting strength of the wooden pieces 10A-10C. Therefore, the joining structure for wooden members of the present invention increases the rigidity and strength of the joints between the wooden pieces 10A-10C, allowing the wooden pieces 10A-10C to be firmly joined together despite the simple structure. In addition, the stiffening effect of the steel plate 20 can be adjusted by adjusting the adhesive area between the side surfaces 11A, 11B of the wooden members 10A to 10C and the steel plate 20, and the number of screws 21 driven from the steel plate 20 into the wooden members 10A, 10B, and the rigidity and strength of the joints between the wooden members 10A, 10B can also be adjusted. (6) The depth of the recess 13 is approximately the same as the thickness of the steel plate 20, and the surface of the steel plate 20 is approximately flush with the abutting side surfaces 11A, 11B of the wooden members 10A to 10C, so that the side surfaces 11A, 11B of the wooden members 10A to 10C can be joined together without any gaps.

[0022] [Example] As shown in Fig. 9, nine specimens, No. 1 to No. 9, were fabricated and subjected to a vertical load P to measure the relative displacement δ between the pieces of wood. Specimen No. 1 is a comparative example that represents the prior art, and specimens No. 2 to No. 9 are examples of the present invention. Each test specimen consisted of an inner piece of wood sandwiched between two outer pieces of wood, and these three pieces of wood were joined with bolts (see Figures 13 and 14). The wood is made of hinoki cypress, with the grain direction running lengthwise. The cross section of the wood is a square measuring 120mm x 120mm. The screws used to fasten the circular plate (steel plate) are Nedanot manufactured by Synegic Co., Ltd., and are the size shown in Figure 10.

[0023] Only specimen No. 6 had a type B circular plate (steel plate), while specimens other than specimen No. 6 had type A circular plates (steel plates). As shown in Figure 11, in type A, no countersunk recess for accommodating the circular plate is formed on the side of the wood, and the circular plate abuts against the surface of the wood. In addition, in type A, the head of the screw is accommodated in a countersunk recess in the screw hole of the circular plate, and the base end face of the screw is approximately flush with the surface of the circular plate. On the other hand, in type B, as shown in Figure 12, the circular plate is accommodated in a countersunk recess in the wood. In addition, in type B, the screw hole of the circular plate does not have a countersunk recess for accommodating the screw head. The joint direction in the grain direction means that the inner and outer pieces of wood are joined by being positioned approximately parallel to each other, as shown in Figure 13. The joint direction perpendicular to the grain direction means that the inner and two outer pieces of wood are joined by being positioned approximately perpendicular to each other, as shown in Figure 14.

[0024] As shown in Figures 13 and 14, the loading test involved placing the outer piece of wood that made up the test specimen on a jig, applying a vertical load (shear force) P to the inner piece of wood in the direction indicated by the white arrows in Figures 13 and 14, and measuring the relative displacement δ between the pieces of wood. Figures 15 and 16 show the results of the loading test (showing the relationship between the vertical load applied to the test specimen and the relative displacement between the pieces of wood). Figures 15 and 16 also show the yield strength Py (24 kN) calculated from the material strength of the wood, bolts, and screws.

[0025] As shown in Figures 15 and 16, when the joint direction was in the grain direction, the maximum strength of each specimen reached more than five times the yield strength calculated from the strength of each material, compared to when the joint direction was perpendicular to the grain direction. Furthermore, when the joint direction was in the grain direction, the failure mode of each specimen was such that the relative displacement between the wood pieces reached 40 mm or more, and then splitting failure occurred around the through hole in the wood where the bolt was inserted, reaching the maximum strength. For each specimen, the initial stiffness in the relationship between vertical load P and relative displacement δ showed high stiffness up to a load level that exceeded the yield strength Py calculated from the strength of each material. The maximum strength of the specimens in the load-displacement relationships shown in Figures 15 and 16 corresponds to the yield strength of the joint structure of the wooden members. Thus, taking into account the test results regarding the maximum strength, relative displacement at maximum strength, initial rigidity, and failure mode of each specimen in the examples, it can be seen that the wooden member joining structure of the present invention can firmly join wooden members to each other.

[0026] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. In the above-described embodiments, the steel plate 20 is fixed to the wooden pieces 10A to 10C with the screws 21, but this is not limiting. The steel plate 20 may be fixed to the wooden pieces 10A to 10C with an adhesive applied to the joint surface between the steel plate 20 and the wooden pieces 10A to 10C, or the steel plate 20 may be fixed to the wooden pieces 10A to 10C with an adhesive in addition to the screws 21. Fixing the steel plate 20 to the wooden pieces 10A to 10C with an adhesive in this manner has the following effect: The steel plate 20 fixed with the adhesive further suppresses shear deformation along the joint surface between the wooden pieces 10A to 10C, thereby increasing the joint strength and shear rigidity between the wooden pieces 10A to 10C. [Explanation of symbols]

[0027] 1...Wooden bridge (jointed structure of wooden members) 1A...Jointed structure of wooden members 10, 10A, 10B, 10C...Wood (wooden components) 11A, 11B... Side surface (outer surface) 11C... Bottom surface of recess 12... Through hole 13...recess in which a steel plate is accommodated 14...recess in which a bearing plate is accommodated 20... Steel plate 21... Screw (rod-shaped connector) 22... Through hole 23... Screw hole 30... Support plate 31... Through hole 40...Bolt 41...Nut

Claims

1. A joining structure for wooden members that joins a plurality of wooden members together, Each of the wooden members has a through hole formed therein, A recess is formed on each of the side surfaces of the wooden members that come into contact with each other, A steel plate having a through hole formed therein is attached to the bottom surface of the recess, A joining structure for wooden members, characterized in that the multiple wooden members are arranged so that the steel plates abut each other and are fixed together with bolts inserted into the through holes of the wooden members and the through holes of the steel plates.

2. The depth of the recess is approximately the same as the thickness of the steel plate, 2. The joining structure for wooden members according to claim 1, wherein the surfaces of the steel plates are substantially flush with the side surfaces of the wooden members that abut against each other.

Images