CLT-based earthquake-resistant reinforcement for existing buildings

Abstract

To develop a seismic structure that reduces the overall weight of a building and improves seismic performance by replacing floor slabs and walls of existing buildings with CLT.SOLUTION: 1. There is provided a seismic reinforcement structure using CLT version 2 to renovate the floor of a building with an existing frame, in which a wire rod installed on an existing beam after dismantling the existing slab and a joint portion 6 with a bolt 51 planted on the wood end surface of the CLT version are filled with filler to be joined to each other. 2. The seismic reinforcement structure according to 1. is characterized in that the CLT version is located on a temporary support bracket 71 attached to the side of the existing beam. 3. The seismic reinforcement structure according to 1. or 2. is characterized in that the existing frame is made of reinforced concrete, the wire rods are slab reinforcements, the slab reinforcements are exposed in a plurality of levels above and below, and the bolts are arranged in an empty stack between the slab reinforcements in an elevational view.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technique for seismic reinforcement of existing buildings. [Background technology]

[0002] When reusing existing buildings through renovation or conversion, seismic retrofitting is necessary depending on factors such as when it was completed and its previous use. In recent years, policies have been implemented to promote the seismic reinforcement of existing buildings in urban areas, and technologies are being developed to efficiently reinforce existing buildings and provide seismic isolation. Earthquake resistance reinforcement includes reducing the weight of the building's live load to reduce the earthquake input to the building, and reinforcing the building's structural strength with braces, etc. Other methods include adopting seismic isolation devices, etc.

[0003] Patent Document 1 (JP 2017-214710 A) proposes a method of renovating an existing building that involves changing the use of a large non-residential building such as a department store to a building with private residential rooms, by providing a daylighting surface in a room that does not face the exterior of the existing building, by creating a daylighting space that penetrates from the roof slab to at least the slab one floor above the floor to which the room belongs, thereby renovating the building into a residential building. Patent Document 2 (JP 2015-190120 A) discloses a seismic retrofitting method in which the rooftop floor and exterior walls of a building are left in place, and some or all of the floor slabs located on the middle and upper floors of the building, which are floors above the lower floors, are removed, thereby reducing the weight of the building and reducing the seismic forces acting on the building. Patent Document 3 (Patent Publication No. 5575561) discloses an earthquake-resistant structure in which multiple reinforcing members, each made of rod-shaped wood material with a metal core embedded longitudinally, are arranged in a diagonal lattice pattern within a structural plane defined by pillars and beams, and both ends of each lightweight reinforcing member are connected to the pillars or beams to improve earthquake resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-214710 A [Patent Document 2] JP 2015-190120 A [Patent Document 3] Patent No. 5575561 Summary of the Invention [Problem to be solved by the invention]

[0005] The purpose of the present invention is to develop an earthquake-resistant structure that reduces the overall weight of a building and improves its earthquake resistance by replacing the floor slabs and walls of existing buildings with CLT. [Means for solving the problem]

[0006] 1. A seismic reinforcement structure in which the floor of an existing building frame is retrofitted using CLT panels, This earthquake-resistant reinforcement structure is characterized by dismantling the existing slab and filling the joints made by the wire rods attached to the existing beams and the bolts planted into the end faces of the CLT slabs with filler material. 2. A seismic reinforcement structure as described in 1., characterized in that the CLT panel is located on a temporary support bracket attached to the side of the existing beam. 3. An earthquake-resistant reinforcement structure as described in 1 or 2, characterized in that the existing structure is reinforced concrete, the wire rods are slab reinforcement, the slab reinforcement is exposed in multiple layers above and below, and bolts are arranged in an open overlap state between them when viewed from above. 4. A seismic reinforcement structure in which the walls of an existing building are retrofitted using CLT panels, A single earthquake-resistant wall is made up of multiple CLT panels installed on the same plane. Each CLT panel is an earthquake-resistant reinforcement structure in which bolts planted on the upper or lower end face of the board and anchors driven into the existing structure protrude opposite each other, and are joined at joints filled with filling material. 5. A seismic reinforcement structure as described in 4., characterized in that the joints at the end wood portions of adjacent CLT panels are on opposite sides above and below. 6. A seismic reinforcement structure as described in 4. or 5., characterized in that adjacent CLT slabs are joined with linear connectors cast from the surface. [Brief description of the drawings]

[0007] [Figure 1] Diagram showing an example of a cross section of a fire-resistant structural material [Diagram 2] 1F, Example of underground beam plan [Diagram 3] Example of 1st floor wall and 2nd floor beam plan [Figure 4] Diagram showing an example of earthquake-resistant reinforcement structure (joint between short side CLT floor slab and RC beam) [Diagram 5] Diagram showing an example of earthquake-resistant reinforcement structure (joint between long side CLT floor slab and RC beam) [Figure 6] Diagram showing earthquake-resistant reinforcement structure 20 (attachment diagram of existing RC frame and CLT wall panel) [Figure 7] Diagram showing earthquake-resistant reinforcement structure 30A (attachment diagram of existing S beams and CLT panels) [Figure 8] Diagram showing earthquake-resistant reinforcement structure 30B (attachment diagram of existing S beam and CLT plate) [Figure 9] Diagram showing earthquake-resistant reinforcement structure 30C (attachment diagram of existing S beam and CLT panel) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention is a seismic reinforcement structure that can be applied to buildings that have been seismically retrofitted by reducing the weight of the structure by retrofitting the floor slabs or walls of existing reinforced concrete or steel-framed buildings with CLT slabs. The present invention is applicable when reusing existing buildings through renovation, conversion, etc., and when carrying out seismic retrofitting in accordance with revised building standards, etc. In addition to seismic resistance, the present invention can also improve design by adding a wooden texture to architectural spaces. The present invention is a reinforcement structure that simplifies the joining of floor slabs or wall slabs.

[0009] The floor reinforcement structure is made by joining wires (such as rebars and bolts) attached to the existing beams to bolts attached to the CLT side at the joints. The wire rod is, for example, a reinforcing bar (existing slab main bar or post-installed anchor, etc.) installed in an existing RC beam, or a bolt (existing or newly installed) installed in an existing steel beam. For existing RC beams, existing slab reinforcement bars and bolts installed on the CLT side can be overlapped and joined. When pouring concrete into the joints, temporary support brackets and angle irons for temporarily supporting the CLT slab can be used as formwork. By removing the floor slabs of the existing building and replacing them with CLT slabs, the weight of the structure was reduced while maintaining the floor area of ​​the building. The surface of the seismically reinforced CLT can be used as a finishing surface, giving the architectural space a wooden texture after renovation.

[0010] In the reinforcement structure of the wall, the anchors installed in the existing structure such as the beams and the bolts installed on the CLT side are overlapped and joined. It is also possible to use the rebar of the existing wall without installing new anchors. When renovating the walls of existing buildings, CLT panels are added to or replaced with existing walls, adding the rigidity of the CLT to the building and improving its earthquake resistance. As with the floors, the surface of the seismically reinforced CLT can be used as the finishing surface for the walls as well, giving the architectural space a wooden texture after renovation.

[0011] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a seismically retrofitted building in which a seismic reinforcement structure has been applied to a building 1 having an existing reinforced concrete structure 11, where (a) is a vertical cross-sectional front view and (b) is a vertical cross-sectional side view. The figure shows a seismic reinforcement structure 10 in which the floor slab has been retrofitted to a CLT plate, and a seismic reinforcement structure 20 in which the walls have been retrofitted to a CLT plate. In the figure, the seismic reinforcement structure 10 is installed on the second and third floors, and two rows of the seismic reinforcement structure 20 are installed. The reinforcement structure can be applied to the entire structure or to part of it.

[0012] Figure 2 shows the plan of the first floor and underground beams. The walls that will be seismically reinforced from the first floor to the upper floors are shown as seismically reinforced structure 20. The wall portions that will not be renovated are shown as existing beams 13. In this renovation, the slab that makes up the first floor is left as the existing slab 12, without being renovated.

[0013] Figure 3 shows the plan of the first floor walls and second floor beams. The earthquake-resistant reinforcement structure 10, which is a floor reinforcement, is installed on most of the second floor. The earthquake-resistant reinforcement structure 20 for wall reinforcement is installed in the same location as in FIG.

[0014] Figure 4 shows the earthquake-resistant reinforcement structure 10. It shows the structure of the joint between the CLT slab and the RC beam on the short side of the floor. The existing slab connected to the existing beam 13 is removed and replaced with a CLT panel 2. A joint 6 is provided between the existing beam 13 and the CLT panel 2 to connect the two. At the joint 6, the slab reinforcement 41 extending from the existing beam 13 is left to a length approximately equal to the width of the joint 6, while the heads of the bolts 51 inserted into the CLT slab protrude by a length approximately equal to the width of the joint 6, so that the slab reinforcement 41 and the bolts 51 intersect. The joint 6 is filled with a cement-based material such as grout as a filler 61.

[0015] The slab reinforcement 41 has main reinforcements arranged above and below, and the bolts 51 are provided at a different height from the slab reinforcement 41, so that the slab reinforcement 41 and the bolts 51 are arranged in an overlapping state. The rebar is placed in an open overlapping state at the joint and then solidified with filler, creating a strong bond. An L-shaped temporary support bracket 71 is attached to the existing beam 13, and the end of the CLT panel is placed on this temporary support bracket 71, and temporarily set so that a gap of 6 cm is created at the joint. The temporary support bracket 71 also serves as a formwork. The temporary support bracket 71 is fixed by drilling a through hole 73 in the existing beam 13 and passing a through bolt 72 through the through hole 73.

[0016] Figure 5 shows the seismic reinforcement structure 10 on the long side of the floor. This is the structure of the joint between the CLT slab on the long side of the floor and the RC beam. Similar to the seismic reinforcement structure on the short side of the floor shown in Figure 4, there is a gap between the existing beam 13 and the end 24 of the CLT slab 2, and the slab reinforcement 41 and bolts 51 are arranged in an open overlap state at different heights and are solidified with filler material. On this long side, a formwork 7 is provided below the joint 6, and the bottom surface of the formwork is supported by a support 74, and the filling material 61 is filled in.

[0017] Fig. 6 shows an earthquake-resistant reinforcement structure 20 for wall reinforcement. (a) is an elevational structural view, (b) is a cross-sectional view of a joint, and (c) is a vertical cross-sectional view of the joint. In the figure, the CLT panel is attached to an existing wall 18. However, the existing wall can be demolished and replaced with the CLT panel. Also, a new CLT wall can be installed.

[0018] A seismic reinforcement structure 20 is constructed by erecting multiple CLT panels 2 (2a, 2b, 2c, 2d, etc.) between the existing beams 13 above and below the existing structure 11. The upper or lower side of the CLT panel 2 is shortened to form a joint 6. A bolt 52 is planted on the joint 6 side of the CLT panel 2 so that the head protrudes into the joint. Post-installed anchors 42 are provided from the existing beam 13 side toward the joint 6, and the heads of bolts 52 are positioned so as to overlap with the post-installed anchors 42. In this state, filler 61 is filled in and the joint 6 is hardened, thereby forming the earthquake-resistant reinforcement structure 20.

[0019] Figure (b), which shows the cross section of the joint, shows the state in which the CLT panel 2 has been installed along the existing wall 18. The existing wall 18 has been installed on the top surface of the existing beam 13, shifted to the right side, and a new CLT panel wall has been constructed on the open left side. Post-installed anchors 42 are raised from the existing beam 13. Long bolts 52 are planted on the lower end side of the CLT panel 2 and are positioned between the post-installed anchors 42. On the upper side of the existing beam 13, the CLT end is in contact with the existing beam, and no bolt joints are used. However, if an independent CLT wall is to be constructed, strong joints can be constructed above and below using post-installed anchors and bolts.

[0020] The joint state of the adjacent CLT panels 2a and 2b is shown in Figure (c). The top figure shows the plan view of the joint, and the bottom figure shows the longitudinal section. Linear connectors (such as nails or bolts) 53 are driven from the front side of the CLT panels 2a, 2b toward the side of the other CLT panel, firmly joining them to each other to form an earthquake-resistant reinforcement structure 20 in which multiple CLT panels are integrated.

[0021] The earthquake-resistant reinforcement structure 10 and the earthquake-resistant reinforcement structure 20 described based on the drawings are just examples, and the present invention is an earthquake-resistant reinforcement structure in which a gap is provided between the existing beam and the CLT plate, and existing reinforcement bars and post-installed anchors are arranged to overlap with bolts planted to extend from the ends of the CLT plate, and the gap is filled with grout or the like. By providing this earthquake-resistant reinforcement structure, the load on the building structure can be reduced, and earthquake-resistant reinforcement and renovation can be carried out without reducing the floor area more than necessary, making it possible to effectively reuse existing buildings. By using the outer surface of the CLT for the design, it is possible to omit the need for finishing processing for the design.

[0022] Figure 7 shows an example of a seismic reinforcement structure 30A in which the floor of an existing building, which uses steel beams for its existing beams, has been retrofitted with a CLT floor slab. The structure of the joint between the CLT slab 2 and the existing steel beam 14 is shown in Figure 7. The steel beam 14 is an H-shaped steel consisting of upper and lower flanges 15 and a web 16. The existing concrete slab that was placed on the flanges 15 is to be removed and replaced with the CLT panel 2. A joint 6 is provided between the steel beam 14 and the CLT panel 2 to connect the two. At the joint 6, a stud bolt 43 is provided on the flange 15 above the steel beam 14, while a bolt 51 inserted into the CLT slab protrudes into the joint 6, and a reinforcing bar 62 is placed between the stud bolt 43 and the bolt 51. The joint 6 is filled with a cement-based material such as grout as a filler 61.

[0023] The stud bolts 43 to be provided on the flanges 15 of the steel beams 14 may be those buried in the existing floor slab and left in place. Also, new stud bolts may be installed on the flanges 15. 7, a bolt 51 protrudes from the end surface of the CLT panel 2 to the joint 6. Reinforcing bars 62 are placed so as to connect the bolt 51 and the stud bolt 43, and the steel beam 14 and the CLT panel 2 are joined. In the figure, the bolt 51 and the stud bolt 43 are spaced apart, but they can also be arranged so that they overlap. During construction, an L-shaped angle bar 75 is attached to the end face 17 of the flange 15 of the steel beam 14, and the end of the CLT is placed on the L-shaped angle bar 75 and temporarily set with a gap equal to the width of the joint 6. The L-shaped angle bar 75 also serves as a formwork. Concrete is filled into this gap to form the earthquake-resistant reinforcement structure 30A. The L-shaped angle members 75 can be attached by welding or the like.

[0024] Figure 8 shows an example of an earthquake-resistant reinforcement structure 30B in which the floor of an existing building, which uses steel beams, has been retrofitted with a CLT floor slab. The difference from the earthquake-resistant reinforcement structure 30A shown in Figure 7 is that no angle iron is required, since the tip of the CLT slab 2 is supported on the flange 15 of the steel beam 14. The rest is the same, so it will be omitted.

[0025] Figure 9 shows an example of earthquake-resistant reinforcement structure 30C in which the floor of an existing building, which uses steel beams for its existing beams, has been retrofitted with a CLT floor slab. The difference from earthquake-resistant reinforcement structure 30A shown in Figure 7 is that an angle iron 76 is attached to end face 17 of flange 15 so that the receiving surface 77 of angle iron 76 is lower than flange 15. By lowering the receiving surface of angle iron 76, a thicker CLT slab can be used, allowing the floor load to be increased. Alternatively, the floor level can be lowered to increase the interior height. The rest is the same, so it will be omitted here. [Explanation of symbols]

[0026] 1. Building 11 Existing structure 12 Existing slab 13 Existing beam 14 Steel beam 15 Flange 16 Web 17 End face 18 Existing wall 2 CLT version 21 End of wood 24 End 3 Beds 41 Slab Reinforcement 42 Post-installed anchor 43 Stud bolt 51, 52 volts 53 Linear Connectors 6 Joint 61 Filling material 62 Reinforcement Bars 7 Formwork 71 Temporary support bracket 72 Volts 73 Through hole 74 Support 75, 76 L-shaped angle material 77 Receiving surface 8 Earthquake-resistant walls 10, 20, 30A, 30B, 30C seismic reinforcement structure

Claims

1. This is a seismic reinforcement structure in which an existing wall of a building with an existing framework is retrofitted with CLT panels, and one seismic wall is composed of the existing wall and multiple CLT panels installed in the same plane on one side of the existing wall. Each CLT panel is fitted with bolts on the upper or lower end of the board and installed in the existing structure. The joints filled with the filler are alternately provided above and below, with the anchors facing each other and protruding from the opposite sides. A seismic reinforcement structure characterized in that a CLT panel and the existing wall are joined.

2. Adjacent CLT panels are connected with linear connectors cast into the surface.

2. The earthquake-resistant reinforcement structure according to claim 1.

Images