JP7836046B2 - Joint structure between beams and seismic walls - Google Patents

Description

This invention relates to a joint structure between a beam and a seismic wall.

The need to prevent global warming and to improve the health of forest resources and the forestry industry is attracting attention, and the active use of wood-based materials is also required from the perspective of ESG investment and SDGs. Therefore, cross-laminated timber (CLT), made by overlapping sawn timbers with the fiber directions perpendicular to each other, is sometimes used as a seismic wall in structural frameworks.

A seismic wall is a structural member that, along with the columns and beams that make up the frame, bears the stress generated during earthquakes, preventing deformation and failure of the frame. Ideally, seismic walls should be connected to the columns and beams to cover the entire frame. However, depending on the building's layout, they can also be used as intermediate walls, not connected to the columns, but fixed to the beams at the top and bottom. In such structures, the CLT seismic wall and beam are often connected via connecting hardware using drift pins.

Patent documents 1 and 2 describe a method for using CLT (Cross-Laminated Timber) seismic walls as intermediate walls. This method utilizes connecting fittings on both the left and right sides of the upper and lower ends of the CLT seismic wall, and connecting fittings in the center of both ends, both connected to the beam by drift pins. As a result, the connecting fittings on the left and right sides primarily bear the bending stress (tensile force) acting on the CLT seismic wall, while the connecting fitting in the center primarily bears the shear force acting on the CLT seismic wall.

Japanese Patent Publication No. 2019-119990 Japanese Patent Publication No. 2022-144037

However, when using drift pins for joining, there is a slight clearance between the through-hole of the joining fitting and the drift pin. This clearance delays the stress transfer from the frame to the shear wall. Therefore, in cases where both joining fittings are connected by drift pins, as in the technologies described in Patent Documents 1 and 2, the stress transfer through both fittings begins to bear stress with the same degree of delay. This results in the joining fitting bearing both vertical and horizontal stresses simultaneously. Consequently, there is a problem in appropriately designing the joining fitting according to the stress it bears.

In view of the above points, the present invention aims to provide a joint structure between a beam and a seismic wall that allows for the appropriate design of the joint members (joint fittings) according to the stress being borne.

The beam-to-shear wall joint structure of the present invention is a joint structure between a beam of a frame and a shear wall made of wood material, comprising a central joint member that joins the central part of the upper and lower ends of the shear wall to the beam, and two side joint members that join the beam to the beam on both sides of the upper and lower ends of the shear wall, respectively, the central joint member comprising a central fixing part fixed to the beam, a flat central plate part extending vertically from the central fixing part, and central protruding parts projecting in both directions in the thickness direction of the shear wall from the central plate part, and the side joint members comprising a side fixed to the beam The structure comprises a central fixing portion and a flat plate-shaped side plate portion extending vertically from the side fixing portion and having multiple through holes. The central plate portion and central projection portion are inserted into central grooves formed in the center of the upper and lower ends of the seismic wall, with a portion between them formed of a solidified filler having greater compressive strength than the wood material. The side plate portions are inserted into side grooves formed on both sides of the upper and lower ends of the seismic wall, respectively. A drift pin is inserted through through holes formed in the seismic wall and through holes formed in the side plate portions.

According to the beam-to-shear wall connection structure of the present invention, the shear wall is connected to the beam via a central connecting member having a central protrusion that receives horizontal bearing pressure. Since there is a solidified filler portion between these members, horizontal stress from the beam is directly transmitted to the shear wall. On the other hand, vertical stress from the beam is not directly transmitted to the shear wall because slippage occurs between the beam and the central connecting member. As a result, horizontal stress from the beam is transmitted to the shear wall from the central connecting member even without initial displacement, and the central connecting member primarily bears the shear force acting on the shear wall.

The shear wall is also connected to the beams at the side joint members, but these are joined with drift pins. Since a small gap inevitably exists between the drift pins and the through-holes in the shear wall, the stress from the beam is transmitted to the shear wall only after initial displacement has occurred. As a result, the side joint members primarily bear the bending stress acting on the shear wall. Therefore, it is possible to appropriately design the central and side joint members according to the stress they bear.

In the beam-and-shear wall joint structure of the present invention, the shear wall is made of CLT material, and it is preferable that the fiber direction of the sawn boards constituting the CLT material is in the vertical and horizontal directions.

In this case, the vertical component of the stress transmitted from the beam to the shear wall can be suitably borne by the sawn shingle with its fiber direction perpendicular, and the horizontal component can be suitably borne by the sawn shingle with its fiber direction horizontal.

Furthermore, in the beam-and-shear wall joint structure of the present invention, the filling material is preferably a cement-based solidifying agent.

In this case, it becomes possible to easily obtain a filling material with greater compressive strength than the wood material constituting the seismic wall.

Furthermore, in the beam-to-shear wall joint structure of the present invention, it is preferable that the beam has a portion made of wood material, and that a portion made of heat sink material is provided between the beam and the shear wall.

In this case, the heat sink material forms a heat sink, making it difficult for the heat generated when the seismic wall burns in a fire to be transferred to the wooden part of the beam. The heat sink material is, for example, solidified mortar, but other materials may also be used.

A schematic front view of a joint structure between a beam and a seismic wall according to the first embodiment of the present invention. A schematic cross-sectional view along the line II-II in Figure 1. A schematic cross-sectional view along the line III-III in Figure 1. Schematic cross-sectional view along line IV-IV in Figure 3. A schematic front view of a joint structure between a beam and a seismic wall according to a second embodiment of the present invention. Schematic cross-sectional view along line V-V in Figure 5. Schematic cross-section along the line IIV-IIV in Figure 6.

The beam-and-shear wall joint structure 100 according to the first embodiment of the present invention will be described with reference to Figures 1 to 4. Note that all drawings are for schematic illustration of embodiments of the present invention, and the dimensions are simplified.

The beam-and-shear wall connection structure 100 according to this embodiment is a structure in which a shear wall 20 is provided in an RC (reinforced concrete) frame. Here, the shear wall 20 is connected only to the RC beam (RC beam) 10. However, the shear wall 20 may also be connected to the RC columns of the frame.

The seismic wall 20 is a seismic wall made of wood material, and in this case, it is formed of cross-laminated timber (CLT). However, the seismic wall 20 is not limited to being made of CLT; it may also be made of parallel laminated timber, laminated veneer lumber (LVL), plywood, etc.

In a front view, the seismic wall 20 is joined to the RC beam 10 at both its upper and lower ends via connecting members 30 and 40. The connecting members 30 and 40 consist of a central connecting member 30 and two side connecting members 40.

The central connecting member 30 connects the central part of the upper end of the seismic wall 20 to the RC beam 10 located above it, in a front view. Furthermore, the central connecting member 30 connects the central part of the lower end of the seismic wall 20 to the RC beam 10 located below it, in a front view.

The central connecting member 30 comprises a central fixing portion 31 fixed to the RC beam 10, a flat central plate portion 32 extending from the central fixing portion 31 in the wall direction (vertical direction) of the seismic wall 20, and central protruding portions 33 projecting from the central plate portion 32 in both the thickness direction (front and back directions) of the seismic wall 20.

Here, the central fixing portion 31 consists of a rectangular steel plate with multiple through holes. The central flat plate portion 32 consists of a rectangular steel plate extending upward or downward toward the seismic wall 20 to which it is joined, and one of its vertical ends is fixed to the central part of the central fixing portion 31 by welding or the like.

The central projection 33 consists of two rectangular steel plates that protrude in both the front and rear directions, and is fixed to the left and right end faces of the central flat plate portion 32 by welding or other means. As a result, the central flat plate portion 32 and the central projection 33 as a whole have an H-shape or I-shape when viewed from above. In this case, the central projection 33 is fixed to the central fixing portion 31, and the left and right end faces of the central fixing portion 31 and their side end faces are flush, but this is not limited to this configuration.

Furthermore, the central flat plate portion 32 and the central protruding portion 33 may be integrated and made of H-beams, I-beams, or the like. Also, the central protruding portion 33 may be fixed to the center of both the front and rear surfaces of the central flat plate portion 32 by welding or the like, so that the central flat plate portion 32 and the central protruding portion 33 as a whole form a cross shape when viewed from above. Moreover, the central flat plate portion 32 and the central protruding portion 33 as a whole form a "king" shape when viewed from above.

The central connecting member 30 is fixed to the upper and lower surfaces of the RC beam 10 by inserting anchor bolts 51 through through holes formed vertically in the RC beam 10 and through holes formed in the central fixing portion 31.

Furthermore, at the upper and lower ends of the seismic wall 20, a central groove (slit) 21 is formed in the central part, following the outer shape of the central flat portion 32 and central protrusion 33 of the central joint member 30. For example, if the outer shape of the central flat portion 32 and central protrusion 33 of the central joint member 30 is I-shaped when viewed from above, the central groove 21 is formed in the seismic wall 20 so that there is a small gap between this I-shape and the groove. While the shape of this central groove 21 is preferably I-shaped, it may also be a shape that includes an I-shape, such as a rectangle.

The central groove 21 of the seismic wall 20 contains a central flat section 32 and a central protruding section 33, with a solidified filler section 52 between them. The filler has a greater compressive strength than the wood material constituting the seismic wall 20 and is, for example, a cement-based solidifying material such as grout or non-shrink mortar.

For example, at both the upper and lower ends of the seismic wall 20, when the central flat plate portion 32 and the central protruding portion 33 are inserted into the central groove portion 21 at the construction site, filler material can be poured into the gaps created, and the gaps can be filled with the filler material and held in place until the filler material hardens. This ensures that the upper and lower ends of the seismic wall 20 are fixed to the intermediate joint member 30 via the solidified filler material portion 52. Alternatively, the lower end of the seismic wall 20 may have the central joint member 30 pre-fixed at a factory, while the upper end may be filled with filler material and the central joint member 30 fixed at the construction site. It is preferable to waterproof the inner surface of the central groove portion 21 to prevent the seismic wall 20 from absorbing moisture from the filler material when filling the central groove portion 21.

The side joint member 40 comprises a side fixing portion 41 that is fixed to the RC beam 10, and a flat side plate portion 42 that extends from the side fixing portion 41 in the direction of the wall surface (vertical direction) of the seismic wall 20.

Here, the side fixing portion 41 consists of a rectangular steel plate with multiple through holes. The side flat plate portion 42 consists of a rectangular steel plate extending upward or downward toward the seismic wall 20 to which it is joined, and one of its vertical ends is fixed to the central part of the side fixing portion 41 by welding or the like. The side flat plate portion 42 has numerous through holes.

The side connecting members 40 are fixed to the upper and lower surfaces of the RC beam 10, respectively, by inserting anchor bolts 53 through through holes formed vertically in the RC beam 10 and through holes formed in the side flat plate portion 42.

Furthermore, at the upper and lower ends of the seismic wall 20, side grooves (slits) 22 are formed on both the left and right sides, following the outer shape of the side flat plate portion 42 of the side connecting member 40. Also, at the upper and lower ends of the seismic wall 20, numerous through holes are formed, penetrating in the thickness direction, corresponding to the positions of the through holes formed in the side flat plate portion 42.

The side flat plate portion 42 is inserted into the side groove portion 22 of the seismic wall 20, and numerous drift pins 54 are inserted through the through holes formed in the seismic wall 20 and the side flat plate portion 42.

Thus, the seismic wall 20 is joined to the RC beam 10 via a central joint member 30 having a central projection 33 that receives horizontal bearing pressure. The gap between the central joint member 30 and the central groove 31 is filled by a portion 52 made of solidified filler material. Therefore, in the initial stage of load application, the portion 52 made of solidified filler material can bear the horizontal stress from the RC beam 10, while the side joint member 40 can bear the vertical stress from the RC beam 10.

As a result, the horizontal stress from the RC beam 10 is transmitted from the central connecting member 30 to the shear wall 20 even when there is no initial displacement, so the central connecting member 30 mainly bears the shear force acting on the shear wall 20.

The seismic wall 20 is also connected to the RC beam 10 at the side connecting members 40. These are connected by drift pins 54, and a small gap inevitably exists between the drift pins 54 and the through-holes in the seismic wall 20. Therefore, stress from the RC beam 10 is transmitted to the seismic wall 20 only after initial displacement has occurred. As a result, the side connecting members 40 primarily bear the bending stress acting on the seismic wall 20. Bending stress is a stress acting in a direction that rotates around the central connecting member 30, and since it involves a large displacement in the vertical direction, the drift pins 54 function effectively. Therefore, it is possible to appropriately design the central connecting member 30 and the side connecting members 40 according to the stress they bear.

Furthermore, it is preferable that the seismic wall 20 be installed by stacking multiple layers of CLT material with two types of fiber orientations—vertical and horizontal—to be effective against stress in both directions.

Furthermore, if the stress borne by the seismic wall 20 is large, and all connections between the seismic wall 20 and the connecting members are made using drift pins, the connecting members may become large in order to secure the required number of drift pins, potentially making it impossible to arrange the connecting members. However, in this embodiment, the connection between the seismic wall 20 and the central connecting member 30 is made via a portion 52 made of solidified filler material, making it possible to suppress the size of the central connecting member 30.

Next, the beam-and-shear wall joint structure 200 according to the second embodiment of the present invention will be described with reference to Figures 5 to 7. Note that the schematic cross-sectional view along line II-II in Figure 5 is the same as the schematic cross-sectional view along line II-II in Figure 1 of the first embodiment, as shown in Figure 2.

The connection structure 200 with the seismic wall according to this embodiment is a connection structure between the reinforced concrete (RC) beam 70 and the seismic wall 20 via a wooden beam (wooden beam) 60. However, the seismic wall 20 may also be connected to columns of the frame, such as those made of RC construction. The wooden beam 60 corresponds to the portion of the beam made of wood material according to the present invention.

The wooden beam 60 is fixed to the underside of the reinforced concrete beam 70 using fasteners such as bolts (not shown), and its outer surface has a surface layer 62 made of wood, via a fire-resistant coating 61 such as reinforced gypsum board.

In a front view, the seismic wall 20 is joined at its upper end to the wooden beam 60 or RC beam 70 via connecting members 80 and 40, and at its lower end to the RC beam 70 via connecting members 30 and 40. The connecting members 80, 30, and 40 consist of two types of central connecting members 80 and 30 and one type of side connecting member 40.

The first central connecting member 80 connects the central part of the upper end of the seismic wall 20 to the wooden beam 60 located above it, in a front view. The second central connecting member 30 connects the central part of the lower end of the seismic wall 20 to the reinforced concrete beam 70 located below it, in a front view.

The second central joint member 30 is configured identically to the central joint member 30 described above. The first central joint member 80 is configured similarly to the central joint member 30 described above, but here, the central fixing portion 81 is extended in both left and right directions, and the number of through holes is also increased. The side joint member 40 is configured identically to the side joint member 40 described above.

A recess 63 is formed on the underside of the wooden beam 60. The first central joint member 80 is fixed to the underside of the wooden beam 60 by embedding fasteners 91, such as structural screws (panel lead steel, etc.), into the wooden beam 60, through holes formed in the central fixing portion 81, so that the central fixing portion 81 is pressed against the upper surface of the recess 63. A portion 92 made of heat sink material exists in the remaining space of the recess 63.

A recess 71 is formed on the upper surface of the RC beam 70. The second central joint member 30 is fixed to the upper surface of the RC beam 70 by an anchor bolt 72, embedded in the RC beam 70, which passes through a through-hole formed in the central fixing portion 31, so that the central fixing portion 31 is pressed against the bottom surface of the recess 71. The remaining space in the recess 71 contains a portion 93 made of heat sink material.

Furthermore, at the upper and lower ends of the seismic wall 20, a central groove (slit) 21 is formed in the central portion, following the outer shape of the central flat portion 82, 32 and the central protruding portion 83, 33 of the first and second central joint members 80, 30, respectively.

The central groove 21 of the seismic wall 20 is formed by inserting central flat sections 82, 32 and central protrusions 83, 33, with a solidified filler section 52 between them. It is preferable to waterproof the inner surface of the central groove 21 to prevent the seismic wall 20 from absorbing moisture from the filler when filling the central groove 21.

The side connecting members 40 are fixed to the upper surface of the RC beam 70 and the lower surface of the timber beam 60, respectively, by inserting anchor bolts 94 through through holes formed vertically between two recesses 73 formed on the upper surface of the RC beam 70 and two recesses 64 formed on the lower surface of the timber beam 60, and through holes formed in the side fixing portion 41.

Furthermore, a portion 93 made of heat sink material exists in the remaining space of the recess 71 in the RC beam 70. Similarly, a portion 92 made of heat sink material exists in the remaining space of the recess 63 in the wooden beam 60. Thus, a heat sink is formed by portions 92 and 93 made of heat sink material, making it difficult for heat generated when the seismic wall burns in a fire to be transferred to the wooden beam 60. The heat sink material is, for example, solidified mortar, but other materials may also be used.

Furthermore, a compression prevention rod 97, made of steel, is inserted into a through-hole formed vertically through the RC beam 70 and the wooden beam 60 to prevent compression of the wooden beam 60. Its upper and lower end faces abut against the side fixing portion 41 of the side joining member 40.

Furthermore, at the upper and lower ends of the seismic wall 20, side grooves (slits) 22 are formed on both the left and right sides, following the outer shape of the side flat plate portion 42 of the side connecting member 40. Also, at the upper and lower ends of the seismic wall 20, numerous through holes are formed, penetrating in the thickness direction, corresponding to the positions of the through holes formed in the side flat plate portion 42.

The side flat plate portion 42 is inserted into the side groove portion 22 of the seismic wall 20, and numerous drift pins 98 are inserted through the through holes formed in the seismic wall 20 and the side flat plate portion 42.

Thus, in the second embodiment, as in the first embodiment described above, the central connecting members 80 and 30 primarily bear the shear force acting on the seismic wall 20. On the other hand, the side connecting member 40 primarily bears the bending force acting on the seismic wall 20. Therefore, it becomes possible to appropriately design the central connecting members 80 and 30 and the side connecting member 40 according to the stress they bear.

Furthermore, the present invention is not limited to the beam-and-shear wall joint structures 100 and 200 specifically described in the embodiments above, and can be modified as appropriate within the scope of the claims. For example, the beam may be made of steel or the like.

10, 70...RC beam (beam), 20...Seismic wall, 30...Central joint member, second central joint member, joint member, 21...Central groove, 22...Side groove, 31...Central fixing part, 32...Central flat plate, 33...Central protrusion, 40...Side joint member, joint member, 41...Side fixing part, 42...Side flat plate, 51, 53...Anchor bolt, 52...Part made of solidified filler (part made of solidified filler), 54...Drift pin, 60...Wooden beam (part made of wood material of the beam), 61...Fireproof coating, 62...Surface layer, 63, 64...Depression, 71, 73...Depression, 72...Anchor bolt, 80...First central joint member, joint member, 81...Central fixing part, 82...Central flat section, 83...Central protruding section, 91...Fastener, 92, 93...Parts made of heat sink material, 94...Anchor bolt, 97...Compression prevention rod, 98...Drift pin, 100, 200...Joining structure between beam and seismic wall.

Claims (4)

A joint structure between a structural beam and a seismic wall made of wood material,
A central joining member that connects the central part of the upper and lower ends of the seismic wall to the beam,
The seismic wall has two side joining members that connect the upper and lower ends of each side to the beam,
The central joint member comprises a central fixing portion fixed to the beam, a flat central plate portion extending vertically from the central fixing portion, and central protruding portions projecting from the central plate portion in both directions in the thickness direction of the seismic wall.
The side joint member comprises a side fixing portion fixed to the beam and a flat side plate portion extending vertically from the side fixing portion and having a plurality of through holes formed therein.
The central flat portion and the central protruding portion are inserted into the central groove formed in the center of the upper and lower ends of the seismic wall, with a portion in between which a filler having greater compressive strength than the aforementioned wood material has been solidified.
A joint structure between a beam and a seismic wall, characterized in that the side flat plate portion is inserted into side grooves formed on both sides of the upper and lower ends of the seismic wall, and drift pins are inserted through through holes formed in the seismic wall and through holes formed in the side flat plate portion. The aforementioned seismic wall is made of CLT material.
The beam-to-shear wall joint structure according to claim 1, characterized in that the fiber direction of the sawn slab constituting the CLT material is in the vertical and horizontal directions. The beam-and-shear wall joint structure according to claim 1, characterized in that the filler is a cement-based solidifying agent. The beam has a portion made of wood material,
The beam-to-shear wall joint structure according to claim 1, characterized in that a portion made of heat sink material is provided between the aforementioned portion and the shear wall.