Construction method for reducing local section of existing structural beam

Abstract

The invention discloses a construction method for reducing the local section of an existing structural beam. The construction method comprises the following steps that S1, a cuboid beam section reducing area is divided at the bottom of the existing structural beam; a cuboid concrete removing area is divided at the bottom of the existing structural beam; s2, concrete in the concrete removing area is removed, and existing steel bars in the structural beam are exposed; s3, existing bottom ribs and existing stirrups in the area with the reduced beam section are cut off; s4, newly-added bottom bars are installed at the bottom of the post-pouring concrete area; and S5, concrete construction is conducted in the post-pouring concrete area, and construction for reducing the local section of the structural beam is completed after concrete is formed. According to the method, reliable connection is provided between the post-pouring concrete area and the existing structure by arranging the newly-added bottom bars in the post-pouring concrete area, so that the stress performance of the beam meets the requirements after local dismantling, the situation that the whole beam is constructed again after being completely dismantled is avoided, and the construction efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of building construction, and specifically relates to a construction method for reducing the local cross-section of an existing structural beam. Background Technology

[0002] In recent years, the pace of urban expansion has gradually slowed down in modern urban construction, and building construction has gradually shifted from new construction to the renovation and upgrading of existing structures. The renovation and demolition of existing buildings and the construction of new buildings are increasing, which has become an inevitable trend.

[0003] In the reinforcement and renovation of existing structures, due to changes in usage or planning, the original structure can no longer meet the requirements of the structural stress system and the functional needs. It is necessary to reduce the cross-section of the beam locally. If only the reduced section is partially demolished, the missing part will cause the remaining part of the beam to fail to meet the stress requirements. Therefore, in the general process of reducing the cross-section of a beam, the entire beam must be demolished and rebuilt to meet the requirements. Such solutions are costly and the construction process is complicated. Summary of the Invention

[0004] This invention discloses a construction method for partially reducing the cross-section of an existing structural beam. By adding new bottom reinforcement bars within the post-cast concrete area, a reliable connection is provided between the post-cast concrete area and the existing structure. This ensures that the load-bearing performance of the beam after partial demolition meets the requirements, avoids the need to completely demolish the entire beam and reconstruct it, and improves construction efficiency.

[0005] This invention discloses a construction method for reducing the local cross-section of an existing structural beam, comprising the following steps: S1. Define a beam section reduction area at the bottom of the existing structural beam; define a concrete removal area at the bottom of the existing structural beam, and place the beam section reduction area within the concrete removal area. The portion of the concrete removal area excluding the beam section reduction area is the post-cast concrete area. S2. Remove all concrete from the concrete removal area to expose the existing reinforcing bars inside the structural beam, including existing bottom bars and existing stirrups. S3. Remove the existing bottom reinforcement and existing stirrups within the area of ​​the reduced beam cross-section; S4. Install new bottom reinforcement bars at the bottom of the post-cast concrete area. The new bottom reinforcement bars are fixed along the entire length of the concrete removal area. The new bottom reinforcement bars are fixed to the bottom of the existing stirrups located above the area where the beam cross-section is reduced. The two ends of the new bottom reinforcement bars are fixed to the existing structure. S5. Concrete construction is carried out in the area of ​​the post-cast concrete. After the concrete is formed, the construction of reducing the local cross-section of the structural beam is completed.

[0006] A further improvement of the present invention is that a Z-shaped reinforcement is also provided. After the new bottom reinforcement is installed in step S4 and before concrete construction is carried out in the post-cast concrete area, the Z-shaped reinforcement is installed in the post-cast concrete area, so that the lower bend of the Z-shaped reinforcement is fixed to the existing bottom reinforcement, and the upper bend of the Z-shaped reinforcement is located at the top of the post-cast concrete area. The connecting segment between the upper bend and the lower bend is arranged vertically and located at the boundary between the post-cast concrete area and the area where the beam cross-section is reduced.

[0007] A further improvement of the present invention is that, before installing the new bottom reinforcement in step S4, a U-shaped reinforcement is provided, and the U-shaped reinforcement is fixed at the bottom of the existing stirrup above the area where the beam cross-section is reduced. The opening of the U-shaped reinforcement faces upward, and it is necessary to ensure that the bottom elevation of the U-shaped reinforcement is higher than the bottom elevation of the post-poured concrete area. When installing the new bottom reinforcement, the new bottom reinforcement is fixed inside the opening of the U-shaped reinforcement.

[0008] A further improvement of the present invention is that the U-shaped reinforcement is connected to the existing stirrup by welding; and the newly added bottom reinforcement is connected to the U-shaped reinforcement by welding.

[0009] A further improvement of the present invention is that, when installing the new bottom reinforcement in step S4, at least one end of the new bottom reinforcement is connected and fixed to the existing structure by anchoring.

[0010] A further improvement of the present invention is that, when concrete construction is carried out in the post-cast concrete area, a flared opening is made on the side formwork to facilitate the pouring of concrete.

[0011] A further improvement of the present invention is that, when performing concrete construction in the post-cast concrete area, the selected concrete strength is equal to or one grade higher than the concrete strength of the existing structural beam.

[0012] This invention discloses a construction method for partially reducing the cross-section of an existing structural beam. By setting additional bottom reinforcement bars in the post-cast concrete area and adding Z-shaped reinforcement bars on this foundation, a reliable connection is provided between the post-cast concrete area and the existing structure. This further improves the load-bearing performance of the beam after partial demolition, avoids the need to completely demolish the entire beam and reconstruct it, and improves construction efficiency. Attached Figure Description

[0013] Figure 1 This is a side view of the internal structure of the present invention. Figure 1 ; Figure 2 This is a front view of the internal structure of the present invention; Figure 3 This is a side view of the internal structure of the present invention. Figure 2 ; Figure 4 This is a three-dimensional view of the internal structure of the present invention; Figure 5 This is a three-dimensional view of the internal structure of the present invention located at the existing structural column; Figure 6 This is a schematic diagram of the molded product of the present invention; In the diagram: 1. Area with reduced beam cross-section; 2. Area with post-cast concrete; 31. Existing stirrups; 32. Existing bottom reinforcement; 41. Newly added bottom reinforcement; 42. Z-shaped reinforcement; 43. U-shaped reinforcement; 5. Existing structural column; 6. Beam after molding; 7. Existing structural beam. Detailed Implementation

[0014] like Figures 1-6 As shown, the present invention provides a construction method for reducing the local cross-section of an existing structural beam, comprising the following steps: S1. Divide the bottom of the existing structural beam 7 into a beam section reduction area 1; divide the bottom of the existing structural beam 7 into a concrete removal area, and make the beam section reduction area 1 located within the concrete removal area. The part of the concrete removal area excluding the beam section reduction area 1 is the post-cast concrete area 2. S2. Remove all concrete in the concrete removal area and expose the existing steel reinforcement inside the existing structural beam 7. The steel reinforcement includes the existing bottom reinforcement 31 and the existing stirrups 32. S3. Remove the existing bottom reinforcement 31 and existing stirrups 32 in the reduced beam section area 1; S4. Install new bottom reinforcement bars 41 at the bottom of the post-cast concrete area 2. The new bottom reinforcement bars 41 are fixed along the entire length of the concrete removal area. The new bottom reinforcement bars 41 are fixed to the bottom of the existing stirrups 31 located above the beam section reduction area 1. The two ends of the new bottom reinforcement bars 41 are fixed to the existing structure. S5. Concrete construction is carried out in post-cast concrete area 2. After the concrete is formed, the local section reduction construction of the structural beam is completed.

[0015] In this embodiment, both the beam section reduction area 1 and the concrete removal area are cuboids, and the beam section reduction area 1 and the concrete removal area are close to one side of the existing structural column 5. The width of the beam section reduction area 1 is equal to the width of the existing structural beam 7.

[0016] In this embodiment, one end of the newly added bottom reinforcement 41 is fixed to the existing structural column 5 and the other end is fixed to the existing structural beam 7; like Figures 1-5As shown, a Z-shaped reinforcement 42 is also provided. After the new bottom reinforcement 41 is installed in step S4 and before concrete construction is carried out in the post-cast concrete area 2, the Z-shaped reinforcement 42 is installed in the post-cast concrete area 2, so that the lower bend of the Z-shaped reinforcement 42 is fixed with the existing bottom reinforcement 32, and the upper bend of the Z-shaped reinforcement 42 is located at the top of the post-cast concrete area 2. The connecting section between the upper bend and the lower bend is set in the vertical direction and located at the boundary between the post-cast concrete area 2 and the beam section reduction area 1.

[0017] By setting Z-shaped reinforcement 42, the overall strength of the structural beam after the cross-section is reduced is improved. Specifically, the lower bend of the Z-shaped reinforcement 42 is fixed to the existing bottom reinforcement 32, which is integrated with the existing structural beam, thus connecting the lower bend to the existing structure. The upper bend of the Z-shaped reinforcement 42 is located at the top of the post-cast concrete area 2, thus supporting the top of the post-cast concrete area 2. Since one end of the Z-shaped reinforcement 42 is located in the post-cast concrete area 2 and the other end is connected to the structural structure, it can provide a tie force between the post-cast concrete area 2 and the existing structural beam, preventing cracking and separation at the connection between the newly cast part and the existing structure. It can withstand tensile force and provide shear resistance, preventing relative slippage between the newly cast area and the existing structure, thereby ensuring that the load-bearing capacity of the modified structure is not reduced.

[0018] like Figures 1-5 As shown, before installing the new bottom reinforcement 41 in step S4, a U-shaped reinforcement 43 is provided, and the U-shaped reinforcement 43 is fixed at the bottom of the existing stirrup 31 above the area where the beam cross-section is reduced. The opening of the U-shaped reinforcement 43 faces upward, and it is necessary to ensure that the bottom elevation of the U-shaped reinforcement 43 is higher than the bottom elevation of the post-poured concrete area 2. When installing the new bottom reinforcement 41, the new bottom reinforcement 41 is fixed in the opening of the U-shaped reinforcement 43. By setting the U-shaped reinforcement 43, the bottom of the new bottom reinforcement 41 is supported, thereby improving the overall load-bearing performance.

[0019] Preferably, in this embodiment, the U-shaped reinforcement 43 is connected to the existing stirrup 31 by welding; the newly added bottom reinforcement 41 is connected to the U-shaped reinforcement 43 by welding.

[0020] In this embodiment, when installing the new bottom reinforcement 41 in step S4, at least one end of the new bottom reinforcement 41 is connected and fixed to the existing structure by anchoring. In this embodiment, as shown... Figure 1 As shown, one end of the newly added bottom reinforcement bar 41 is anchored into the existing structural column 5, and the other end is fixed to the existing structural beam 7. The anchoring method can further improve the connection strength between the newly added bottom reinforcement bar 41 and the existing structure.

[0021] Preferably, in this embodiment, as Figure 4 , Figure 5 As shown, this includes multiple newly added bottom reinforcement bars 41 and Z-shaped reinforcement bars 42.

[0022] Preferably, in this embodiment, when concrete construction is carried out in the post-cast concrete area 2, a flared opening is made on the side formwork to facilitate concrete pouring.

[0023] Preferably, in this embodiment, when carrying out concrete construction, concrete with the same strength as or higher than that of the existing structural beam 7 is selected for pouring to ensure construction quality and appearance requirements.

[0024] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for reducing the local cross-section of an existing structural beam, characterized in that, Includes the following steps: S1. Define a beam section reduction area at the bottom of the existing structural beam; define a concrete removal area at the bottom of the existing structural beam, and place the beam section reduction area within the concrete removal area. The portion of the concrete removal area excluding the beam section reduction area is the post-cast concrete area. S2. Remove all concrete from the concrete removal area to expose the existing reinforcing bars inside the structural beam, including existing bottom bars and existing stirrups. S3. Remove the existing bottom reinforcement and existing stirrups within the area of ​​the reduced beam cross-section; S4. Install new bottom reinforcement bars at the bottom of the post-cast concrete area. The new bottom reinforcement bars are fixed along the entire length of the concrete removal area. The new bottom reinforcement bars are fixed to the bottom of the existing stirrups located above the area where the beam cross-section is reduced. The two ends of the new bottom reinforcement bars are fixed to the existing structure. S5. Concrete construction is carried out in the area of ​​the post-cast concrete. After the concrete is formed, the construction of reducing the local cross-section of the structural beam is completed.

2. The construction method for reducing the local cross-section of an existing structural beam as described in claim 1, characterized in that, Z-shaped reinforcement is also provided. After the new bottom reinforcement is installed in step S4 and before concrete construction is carried out in the post-cast concrete area, the Z-shaped reinforcement is installed in the post-cast concrete area, so that the lower bend of the Z-shaped reinforcement is fixed to the existing bottom reinforcement, and the upper bend of the Z-shaped reinforcement is located at the top of the post-cast concrete area. The connecting segment of the upper bend and the lower bend is set in the vertical direction and located at the boundary between the post-cast concrete area and the beam section reduction area.

3. The construction method for reducing the local cross-section of an existing structural beam as described in claim 1, characterized in that, Before installing the new bottom reinforcement in step S4, a U-shaped reinforcement is provided, and the U-shaped reinforcement is fixed at the bottom of the existing stirrups above the area where the beam cross-section is reduced. The opening of the U-shaped reinforcement faces upward, and it is necessary to ensure that the bottom elevation of the U-shaped reinforcement is higher than the bottom elevation of the post-poured concrete area. When installing the new bottom reinforcement, the new bottom reinforcement is fixed inside the opening of the U-shaped reinforcement.

4. The construction method for reducing the local cross-section of an existing structural beam as described in claim 3, characterized in that, The U-shaped reinforcement is connected to the existing stirrup by welding; the newly added bottom reinforcement is connected to the U-shaped reinforcement by welding.

5. The construction method for reducing the local cross-section of an existing structural beam as described in claim 1, characterized in that, When installing the new bottom reinforcement in step S4, at least one end of the new bottom reinforcement is connected and fixed to the existing structure by anchoring.

6. The construction method for reducing the local cross-section of an existing structural beam as described in claim 1, characterized in that, When constructing concrete in the post-cast concrete area, a flared opening is made on the side formwork to facilitate concrete pouring.

7. The construction method for reducing the local cross-section of an existing structural beam as described in claim 1, characterized in that, When constructing concrete in the post-cast concrete area, the selected concrete strength is equal to or one grade higher than that of the existing structural beam concrete.

Images