Joint structure between wooden wall and steel beam, and construction method for joint structure between wooden wall and steel beam

Abstract

To provide a high-proof stress, high-stiffness joint structure between a wooden wall and a steel frame beam, and a method of constructing a joint structure between a wooden wall and a steel frame beam.SOLUTION: A joint structure 100 between a wooden wall and steel frame beam is a joint structure between a wooden wall 1 formed from CLT and steel frame beams 2A, 2B disposed at clearances S1, S2 from the wooden wall 1. The joint structure 100 includes: metal pieces 3, each of which is disposed in a recess 12, the recess 12 lying in a middle in a width direction of the wooden wall 1 and being recessed into the wooden wall 1 from an end 1u, 1d of the wooden wall 1, the end 1u, 1d facing the steel frame beam 2A, 2B side; steel plates 5, each of which is disposed in the clearance S1, S2 between the wooden wall 1 and the steel frame beam 2A, 2B and fixed to the metal piece 3 and the steel frame beam 2A, 2B; and PC steel rods 4, each of which is installed inside the wooden wall 1 and connecting the metal piece 3 with an end 1a in the width direction of the wooden wall 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a joint structure between a wooden wall and a steel beam, and a construction method for the joint structure between a wooden wall and a steel beam. [Background technology]

[0002] Traditionally, CLT (Cross Laminated Timber), which is made by laminating and gluing sawn boards alternately so that their fiber directions are perpendicular, has been used as a component of earthquake-resistant walls in steel frame structures. The connection method between CLT and steel beams is required to have strength, rigidity, and toughness depending on the purpose. Common connection examples include tension bolt connections, screw-retained bracket metal connections, LSB (lag screw bolt) connections, GIR (glued-in rod) connections, and steel plate inserted drift pin connections. Among these, LSB connections, GIR connections, and steel plate inserted drift pin connections are frequently used because they can achieve high strength with relatively few connecting devices.

[0003] LSB and GIR connections have high rigidity and are intended to resist axial forces (pulling forces) at the ends of shear walls caused by rocking deformation. For this reason, a separate mechanism is required to resist shear forces caused by sliding deformation. On the other hand, steel plate insertion drift pin connections have the advantage of being highly tough and capable of simultaneously resisting both pull-out and shear forces. It is also possible to combine multiple connection methods within a single shear wall, such as using GIR connections for pull-out forces and steel plate insertion drift pin connections for shear forces.

[0004] The following Patent Documents 1 to 3 have proposed techniques for wooden earthquake-resistant walls that use joining techniques that resist shear forces. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-80569 [Patent Document 2] Japanese Patent Application Publication No. 2018-188845 [Patent Document 3] Japanese Patent Application Publication No. 2020-101052 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technologies in Patent Documents 1 to 3 all use steel-inserted drift pin joints as their shear resistance mechanism. Because the bearing pressure of the wood by the drift pins is used as the strength-bearing mechanism, toughness is ensured, but low strength and rigidity due to the small bearing area are an issue. Furthermore, because the bearing area is similarly small, the wood is severely damaged during large deformation after yielding, which reduces the reusability of CLT.

[0007] In view of the above circumstances, the present invention provides a joint structure between a wooden wall and a steel beam that has excellent strength and rigidity, and a construction method for the joint structure between a wooden wall and a steel beam. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention employs the following means. That is, the joint structure between a wooden wall and a steel beam according to the present invention is a joint structure between a wooden wall made of CLT and a steel beam arranged with a gap between the wooden wall and the steel beam, and the joint structure is such that the middle of the wooden wall in the width direction is A recess formed therein, The wooden wall is recessed from the end facing the steel beam into the wooden wall. The aforementioned The structure comprises metal fittings placed in the recess, a steel plate placed in the gap between the wooden wall and the steel beam and fixed to the metal fittings and the steel beam, and a PC steel rod provided inside the wooden wall and connecting the metal fittings to the widthwise end of the wooden wall.

[0009] In this joint structure between a wooden wall and a steel beam, metal fittings are installed in the recesses of the wooden wall, and the metal fittings are connected to the widthwise ends of the wooden wall with PC steel rods. As a result, the surface of the recess facing the center in the widthwise direction (the metal fitting side) becomes the bearing surface. By installing metal fittings in the recesses, a large bearing surface can be secured, thereby achieving high strength and rigidity.

[0010] Furthermore, the joint structure between a wooden wall and a steel beam according to the present invention may have mortar filled between the widthwise end of the recess and the metal fittings.

[0011] In this joint structure between a wooden wall and a steel beam, the gap between the widthwise end of the recess and the metal fittings is filled with mortar, which prevents the metal fittings from rattling within the recess.

[0012] Furthermore, the construction method for a joint structure between a wooden wall and a steel beam according to the present invention is a construction method for a joint structure between a wooden wall formed of CLT and a steel beam placed with a gap between the wooden wall, and includes forming a recess in the middle of the wooden wall in the width direction from the end of the wooden wall facing the steel beam into the interior of the wooden wall, forming a communication hole connecting the recess and the end of the wooden wall in the width direction, placing metal fittings in the recess, placing a PC steel rod in the communication hole, temporarily tightening the metal fittings with the PC steel rod, filling the gap between the end of the recess in the width direction and the metal fittings with mortar, finally tightening the PC steel rod before the mortar hardens, and placing a steel plate in the gap between the wooden wall and the steel beam and fixing the steel plate to the metal fittings and the steel beam.

[0013] In this construction method for joining a wooden wall and a steel beam, metal fittings are installed in the recesses of the wooden wall, and the metal fittings are connected to the widthwise ends of the wooden wall with PC steel rods. As a result, the surface of the recess facing the center in the widthwise direction (the metal fitting side) becomes the bearing surface. By installing metal fittings in the recesses, a large bearing surface can be secured, thereby achieving high strength and rigidity. [Effects of the Invention]

[0014] According to the joint structure between a wooden wall and a steel beam and the construction method for the joint structure between a wooden wall and a steel beam of the present invention, high strength and high rigidity can be achieved. [Brief explanation of the drawings]

[0015] [Figure 1] 1A is a front view schematically showing a joint structure between a wooden wall and a steel beam according to one embodiment of the present invention, and FIG. 1B is an enlarged cross-sectional view of part A in FIG. 1A. [Figure 2] FIG. 1(a) is a top view showing a schematic diagram of a joint structure between a wooden wall and a steel beam according to one embodiment of the present invention, and FIG. 1(b) is a cross-sectional view of an enlarged portion including parts B and C in (a). [Figure 3] (a) A top view, (c) a side view, and (b) a front view showing the configuration of the embedded metal fittings. [Figure 4] 1 is a spring model of a joint structure between a wooden wall and a steel beam according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing deformation of the end of a wooden wall. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a joint structure between a wooden wall and a steel beam according to an embodiment of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a front view (a) showing a schematic diagram of a joint structure between a wooden wall and a steel beam according to one embodiment of the present invention, and FIG. 1 is an enlarged cross-sectional view (b) of part A in (a). As shown in Fig. 1(a), a wooden wall 1 and a steel beam 2 are joined by a wooden wall-to-steel beam joint structure (hereinafter referred to as "wall-to-beam joint structure") 100. The joint structure 100 includes embedded metal fittings (metal fittings) 3, PC steel rods 4, and steel plates 5.

[0018] The extension direction of the beams 2 is the X direction, the other horizontal direction perpendicular to the X direction is the Y direction, and the direction perpendicular to the X and Y directions is the Z direction. The X direction of the wooden wall 1 is sometimes referred to as the width direction.

[0019] The wooden wall 1 is made of CLT. The wooden wall 1 is in the form of a board. The board surface of the wooden wall 1 faces the Y direction. In this embodiment, the wooden wall 1 is seven layers and seven plies, and the thickness of the wooden wall 1 is 210 mm.

[0020] A downwardly recessed mortise (recess) 12 is formed in an upper end 1u of the wooden wall 1. An upwardly recessed mortise 12 is formed in a lower end 1d of the wooden wall 1.

[0021] Figure 2 shows (a) a top view of a schematic diagram of a joint structure between a wooden wall and a steel beam in one embodiment of the present invention, and (b) a cross-sectional view of an enlarged portion including parts B and C in (a). As shown in Fig. 2(a), the mortise 12 is formed in approximately the center in the width direction (X direction) of the wooden wall 1. The mortise 12 is formed in approximately the center in the thickness direction (Y direction) of the wooden wall 1.

[0022] 2(b), machined holes (communicating holes) 13 are formed in the wooden wall 1 at locations where PC steel rods 4, washers 42, and nuts 43 (described later) are to be placed. The machined holes 13 have a pair of straight portions 13a through which the PC steel rods 4 are inserted, and a notched portion 13b that is recessed from the end portion 1a in the width direction of the wooden wall 1 toward the center in the width direction and communicates with the straight portions 13a.

[0023] As shown in FIG. 1(a), beams 2 are arranged above and below wooden wall 1. Of the beams 2, the one arranged above wooden wall 1 is referred to as upper beam 2A, and the one arranged below wooden wall 1 is referred to as lower beam 2B. Upper beam 2A is arranged above wooden wall 1 with a gap S1. Lower beam 2B is arranged below wooden wall 1 with a gap S2. Upper beam 2A and lower beam 2B are formed of H-shaped steel.

[0024] FIG. 3 shows the configuration of the embedded metal fittings, with (a) a view from above, (c) a view from the X direction, and (d) a view from the Y direction. As shown in FIG. 2(a), the embedded metal piece 3 is placed in the mortise hole 12. As shown in FIG. 3, the embedded metal piece 3 has a four-sided frame portion 31, an upper surface plate portion 32, and an upright locking portion 33. The four-sided frame portion 31 is formed into a four-sided frame in a plan view. The upper surface plate portion 32 is provided at the top center of the four-sided frame portion in the X direction. The upright locking portion 33 protrudes upward from the upper surface plate portion 32. A pair of upright locking portions 33 are provided spaced apart in the Y direction.

[0025] The four-sided frame portion 31 has an end surface frame portion 36 that extends along the YZ directions at the end in the X direction. Mounting holes 36a that penetrate in the X direction are formed in the end surface frame portion 36. The mounting holes 36a are formed in two locations spaced apart in the Y direction.

[0026] As shown in FIG. 2(b), a gap S3 between the end of the mortise 12 in the width direction and the embedded metal piece 3 is filled with mortar M.

[0027] One end 4a of the PC steel rod 4 is inserted into the mounting hole 36a. A nut 41 is screwed onto one end 4a of the PC steel rod 4. The PC steel rod 4 is inserted into the straight portion 13a of the machined hole 13 in the wooden wall 1. The PC steel rod 4 extends in the X direction. A washer 42 is attached to the other end 4b of the PC steel rod 4, and a nut 43 is screwed onto it. Two PC steel rods 4 are inserted into one washer 42. The washer 42 is attached to the cutout portion 13b of the machined hole 13. This connects the end 1a of the wooden wall 1 and the embedded metal fitting 3.

[0028] In the mortise 12, the surface facing the center in the width direction (the embedded metal fitting 3 side) is the bearing surface 15. The bearing surface 15 is shown by a thick line in Figure 1. In Figure 1, the shear surface 16 in the wooden wall 1 is shown by a two-dot chain line.

[0029] As shown in FIG. 1(a), the steel plate 5 is disposed in the gap S1 between the wooden wall 1 and the upper beam 2A. The steel plate 5 is disposed in the gap S2 between the wooden wall 1 and the lower beam 2B. The steel plate 5 is formed in a plate shape. The plate surface of the steel plate 5 faces in the Y direction.

[0030] As shown in Figure 3, the lower end of the steel plate 5 on the upper beam 2A side is arranged between a pair of vertical locking portions 33 of the embedded metal fittings 3. The lower end of the steel plate 5 is joined to the pair of vertical locking portions 33 with fasteners 52 such as high-tension bolts. The upper end of the steel plate 5 is joined to the upper beam 2A with fasteners (not shown) such as high-tension bolts. The steel plate 5 on the lower beam 2B side has a configuration in which the steel plate 5 on the upper beam 2A side is turned upside down, and a description thereof will be omitted.

[0031] As shown in FIG. 1( a ), the lower part of the wooden wall 1 and the lower beam 2 B are joined by an axial force resisting connector 18 .

[0032] 4 shows a spring model of the joint structure 100. Assuming that the horizontal force (shear force) generated in the wooden wall 1 is 500 kN, the design is carried out taking into consideration the following points (1) to (4).

[0033] (1) By increasing the edge distance of the mortise holes on the top and bottom edges of the wooden wall 1 (the distance L1 from the washer 42 to the bearing surface 15 shown in Figure 2(b)), the brittle fracture of the CLT that forms the wooden wall 1 can be prevented from occurring early. Specifically, the total shear strength of the convex parts on both sides (the parts where no mortise holes 12 are formed at the top and bottom ends of both sides of the wooden wall 1 in the width direction) 14 (see Figure 1) is designed to be 1000 kN, twice the expected horizontal force.

[0034] The calculation method is as follows: The depth of the mortise L2 (see Figure 1(b)) is set to 500 mm (the depth of the bearing surface 15 is also 500 mm), the effective shear width W1 (see Figure 2(b)) is set to 210 mm for all 7 plies, and the effective bearing width W2 is set to 150 mm for 5 plies. The shear strength of CLT is 2.7 N / mm 2is commonly used, and assuming that the convex portions 14 on both sides deform as shown in Figure 5, if the edge distance L1 is secured at 900 mm on one side (ensuring a total of 1800 mm on both sides), it is calculated that there will be no shear failure even under a load of 1000 kN, according to the following formula (1).

[0035]

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[0036] The shear modulus of CLT is 500N / mm 2 is commonly used, and from the following formula (2), the shear stiffness of the CLT end in this case is 756 kN / mm.

[0037]

number

[0038] (2) By increasing the bearing area, the compressive deformation of the CLT cross section subjected to bearing pressure is suppressed, and the strength and rigidity are increased to be equal to or greater than that of steel plate-inserted drift pin joints. Specifically, the total yield strength of the bearing surface is designed to be 1000 kN, and the bearing surface is designed to remain within its elastic range until the protrusion 14 undergoes brittle fracture.

[0039] The calculation method is as follows: The surface pressure stiffness of 7-layer 7-ply CLT is 19.4N / mm 3 , yield stress is 20N / mm 2 Therefore, if the bearing surface 15 is 150 mm x 500 mm x 2 locations, the bearing stiffness is 2910 kN / mm from the following formula (3), and the yield strength is 3000 kN from the following formula (4), which is a design with a considerable margin.

[0040]

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[0041]

number

[0042] To achieve this yield strength and bearing rigidity with a steel-plate-insertion drift pin joint, each drift pin would have a yield strength of 38 kN and a rigidity of 42 kN / mm, which would require the installation of more than 70 drift pins even without considering reduction, making fitting and construction extremely difficult.From the above, it can be seen that the joint structure 100 of the above embodiment has a simpler design and higher strength and rigidity than a steel-plate-insertion drift pin joint.

[0043] (3) The thickness of the embedded metal fittings 3 shall be designed so that buckling does not occur under a load of 1000 kN. (4) Steel plate 5 is designed to yield at 500 kN. The shape and material are examined using finite element analysis.

[0044] Next, a method for constructing the joint structure 100 will be described. With the wooden wall 1 laid down (horizontally), a square chisel is used to form mortises 12 at both ends of the wooden wall 1. Mortar will be poured into the gaps S3 in a later process, so it does not matter if the four corners are not right angles.

[0045] A processed hole 13 is formed so as to communicate with the mortise 12. A water-repellent agent is applied to the inside of the mortise 12.

[0046] An embedded metal fitting 3 is placed in the mortise hole 12. A PC steel rod 4 is placed in the processed hole 13. The embedded metal fitting 3 is temporarily tightened with the PC steel rod 4, nut 41, washer 42 and nut 43.

[0047] The wooden wall 1 is erected. Mortar M is poured into the gap S3 between one of the mortise holes 12 facing upward and the embedded metal fitting 3. Before the mortar M hardens, the PC steel rod 4, nut 41, washer 42, and nut 43 are fully tightened.

[0048] After checking that the mortar M has hardened, the same process is carried out on the other side of the mortise 12. Then, lay the wooden wall 1 down again.

[0049] Steel plates 5 are placed in the gaps S1, S2 between the wooden wall 1 and the steel beam 2. The steel plates 5 are joined to the embedded metal fittings 3 with connectors 52, and the steel plates 5 are joined to the steel beams 2 with connectors.

[0050] In the joint structure 100 between a wooden wall and a steel beam configured in this manner, an embedded metal fitting 3 is provided in the mortise 12 of the wooden wall 1, and the embedded metal fitting 3 is connected to the widthwise end 1a of the wooden wall 1 with a PC steel rod 4. As a result, the surface of the mortise 12 facing the center in the widthwise direction (the embedded metal fitting 3 side) becomes the bearing surface 15. By installing the embedded metal fitting 3 in the mortise 12, a large bearing surface 15 can be ensured, thereby achieving high strength and high rigidity.

[0051] In addition, since the gap S3 between the widthwise end of the mortise 12 and the embedded metal fitting 3 is filled with mortar M, rattling within the mortise 12 can be suppressed.

[0052] Furthermore, by adjusting the shear performance of the steel plate 5, damage to the wooden wall 1 can be suppressed even up to a large deformation.

[0053] Moreover, by changing the shape of the steel plate 5, the deformation performance of the entire joint structure 100 can be freely adjusted.

[0054] Furthermore, repairs and maintenance after large deformations only require replacing the steel plate 5, making the wooden wall 1 highly reusable and a sustainable construction method.

[0055] The above describes one embodiment of the joint structure between a wooden wall and a steel beam according to the present invention, but the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of its intent. [Explanation of symbols]

[0056] 1 Wooden wall 2 Steel beams 2A upper beam 2B Lower beam 3 Embedded hardware (hardware) 4 PC steel rod 5 steel plate 12 Mortise (recess) 100 Joint structure (joint structure between wooden wall and steel beam) M Mortar

Claims

1. A joint structure between a wooden wall made of CLT and a steel beam arranged with a gap between the wooden wall and the steel beam, A recess formed in the middle of the wooden wall in the width direction, the recess being recessed from the end of the wooden wall facing the steel beam side into the wooden wall, and a metal fitting disposed in the recess; A steel plate disposed in the gap between the wooden wall and the steel beam and fixed to the metal fittings and the steel beam; A joint structure between a wooden wall and a steel beam, comprising a PC steel rod installed inside the wooden wall and connecting the metal fittings to the widthwise ends of the wooden wall.

2. 2. The joining structure between a wooden wall and a steel beam according to claim 1, further comprising mortar filled between the widthwise end of the recess and the metal fitting.

3. A construction method for a joint structure between a wooden wall made of CLT and a steel beam arranged with a gap between the wooden wall and the steel beam, A recess is formed in the middle of the wooden wall in the width direction, the recess being recessed from an end of the wooden wall facing the steel beam into the wooden wall, A communication hole is formed connecting the recess and the end of the wooden wall in the width direction, A metal fitting is placed in the recess, a PC steel rod is placed in the communicating hole, and the metal fitting is temporarily fastened with the PC steel rod. Mortar is filled between the widthwise end of the recess and the metal fitting, The PC steel rod is tightened before the mortar hardens, A construction method for a joint structure between a wooden wall and a steel beam, in which a steel plate is placed in the gap between the wooden wall and the steel beam, and the steel plate is fixed to the metal fittings and the steel beam.

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