Large-section hollow slab beam end shear-resistant reinforcing method and structure

Abstract

The invention relates to a large-section hollow slab beam end shear-resistant reinforcing method and structure, the structure comprises a hollow slab beam, the hollow slab beam comprises a hollow slab top surface and a hollow slab bottom surface which are vertically arranged at an interval, and hollow slab side surfaces located between the front and rear sides and between the left and right sides of the hollow slab top surface and the hollow slab bottom surface; a cavity is defined by the hollow slab top face, the hollow slab bottom face and the hollow slab side faces, brick walls are built at the two ends of a reinforcing area in the cavity, and the reinforcing area is blocked through the brick walls at the two ends and the hollow slab beam side walls. A supporting steel bar set is fixedly arranged in the reinforcing area, a groove is formed in the inner space of the supporting steel bar set, a grouting hole is formed in the top face of the hollow slab, an air bag is placed in the groove, the air bag is placed in the groove through the grouting hole, and a first pouring layer, a second pouring layer and a third pouring layer are sequentially poured in the reinforcing area from bottom to top. Under the condition that the appearance of a bridge is not changed and traffic is not influenced, the shear bearing capacity of the hollow slab is obviously enhanced.

Description

Technical Field

[0001] The present application relates to the field of building construction technology, and in particular to a method and structure for shear reinforcement of ends of large-section hollow slab beams. Background Art

[0002] The 30m hollow slab bridges built earlier were designed according to the JTJ021-89 specification design load, and their web thickness was only 12cm, resulting in insufficient shear section and low shear reserve capacity. With the significant increase in traffic volume in recent years, oblique cracks and bottom transverse cracks frequently appear at the ends of the main beams of these bridges, seriously threatening the safety and durability of the bridges. Existing reinforcement methods mostly involve interrupting traffic, changing the shape of the bridge, or requiring a large amount of rebar planting operations, which not only have a long construction period and high cost, but also have a great impact on traffic. Therefore, it is particularly important to develop a reinforcement method that can effectively improve the shear resistance of the hollow slab beam ends without interrupting traffic while maintaining the original appearance of the bridge. Summary of the invention

[0003] The present invention is mainly aimed at the above-mentioned problems existing in the prior art, and provides a method and structure for shear reinforcement of the ends of large-section hollow slab beams. By opening holes at the ends of the beams and pouring high-strength concrete, the shear bearing capacity of the hollow slabs can be significantly enhanced without changing the shape of the bridge or affecting traffic, thereby improving the stability and safety of the overall structure of the bridge.

[0004] The purpose of the present invention is mainly achieved through the following solutions: A large-section hollow slab beam end shear reinforcement structure comprises a hollow slab beam, wherein the hollow slab beam comprises a hollow slab top surface and a hollow slab bottom surface spaced apart from each other, and hollow slab side surfaces located between the front and rear sides and the left and right sides of the hollow slab top surface and the hollow slab bottom surface, wherein the hollow slab top surface, the hollow slab bottom surface and the hollow slab side surfaces enclose a cavity, brick walls are built at both ends of the reinforcement area in the cavity, and the reinforcement area is blocked by the brick walls at both ends and the hollow slab beam side walls; a supporting steel bar group is fixedly arranged in the reinforcement area, a groove is formed in the internal space of the supporting steel bar group, a grouting hole is opened on the top surface of the hollow slab, an air bag is placed in the groove, and the air bag is placed in the groove through the grouting hole, the side wall of the air bag is connected to an air pipe, and a pressure gauge is installed on the air pipe; a first casting layer, a second casting layer and a third casting layer are cast in sequence from bottom to top in the reinforcement area.

[0005] On the other hand, the present invention provides a method for shear reinforcement of large-section hollow slab beam ends, comprising the following steps: S1. During the construction preparation stage, a small milling machine is used to mill the bridge deck pavement layer, with a range of 90×100cm, located in the area of ​​134cm-234cm at the bridge end; S2. During the grouting hole opening stage, a 70×80cm hole is opened on the leveling layer, with a 10cm wide offset between the hole in the asphalt pavement layer and a 50×60cm hole is opened on the hollow slab, with a 10cm wide offset between the hole in the leveling layer and the hole. When opening the hole, pay attention to retaining the original steel bars; S3, construct the enclosure structure, build brick walls at both ends of the reinforced area in the cavity, and form a closed space between the inner wall of the hollow slab beam; S4, pretreatment stage, use high pressure water gun to clean the internal debris of the reinforcement area and wet the inner wall, then spray concrete interface agent on the inner wall of hollow slab beam and brick wall, and drill holes on the bottom surface of hollow slab before cleaning; S5. Place the supporting steel bar group and the airbag. Install the supporting steel bar group inside the reinforcement area, then place the airbag into the groove of the supporting steel bar group from the grouting hole. Use an air compressor to inflate the airbag to 2Mpa±0.5Mpa. Monitor the air pressure with a pressure gauge to ensure that the airbag forms a stable inner membrane. After reaching the controlled air pressure value, stop inflating and tighten the valve at the end of the air pipe. S6. Concrete pouring: self-leveling concrete with strength grade C50 and initial setting time of no more than 30 minutes is used. Concrete is poured in layers. The height of the first pouring layer is 10 cm. After initial setting, the second pouring layer is 40 cm. After initial setting, the third pouring layer is poured to the bottom of the grouting hole. S7, seal the grouting holes, straighten the original steel bars retained at the grouting holes, tie and weld them, and use grouting material to pour above the top surface of the hollow slab; S8. Bridge deck restoration: According to the bridge deck paving reinforcement diagram, 6 cm thick C40 waterproof concrete is re-paved. After reaching the design strength, 10 cm thick AC-16C medium-grained modified asphalt concrete is paved and compacted with small machinery.

[0006] Preferably, the supporting steel bar group includes a first steel bar member, a second steel bar member and a third steel bar member, the second steel bar member includes two parallel transverse steel bars arranged at the upper part and two parallel transverse steel bars arranged at the lower part, the two ends of the transverse steel bars are respectively fixedly connected to the brick walls at the two ends, and the upper transverse steel bars are centrally arranged, and the lower transverse steel bars are distributed to the front and rear sides, the third steel bar member includes a plurality of longitudinally arranged longitudinal steel bars, the longitudinal steel bars are evenly distributed along the length direction of the transverse steel bars, and the two ends of the longitudinal steel bars are fixedly connected to the inner wall of the hollow slab beam, the longitudinal steel bars are located above the lower transverse steel bars and fixedly connected to the lower transverse steel bars, the first steel bar member includes a plurality of inverted U-shaped steel bars, and the inverted U-shaped steel bars are evenly distributed along the length direction of the transverse steel bars, the lower part of the inverted U-shaped steel bars is fixedly connected to the lower transverse steel bars, and the upper part of the inverted U-shaped steel bars is fixedly connected to the upper transverse steel bars.

[0007] In summary, compared with the prior art, the present invention has the following beneficial technical effects: (1) The present invention pours concrete by opening holes at the ends of beams, thereby increasing the cross-section of the beam ends and effectively improving the shear bearing capacity of the hollow slab; (2) The present invention performs reinforcement construction without interrupting traffic, thus reducing the impact on traffic; (3) The present invention does not change the appearance of the hollow slab beam, does not require planting reinforcement, is simple to operate, has high construction efficiency, and uses air bags as inner membranes, which facilitates construction and ensures the quality of concrete pouring. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 yes Figure 1 Sectional view at AA in the middle; Figure 3 It is a schematic diagram of the structure of the airbag in the present invention.

[0009] Figure numerals: 1-top surface of hollow slab, 2-bottom surface of hollow slab, 3-side surface of hollow slab, 4-brick wall, 5-supporting steel bar group, 6-groove, 7-air bag, 8-air pipe, 9-air pressure gauge, 10-first casting layer, 11-second casting layer, 12-third casting layer, 51-first steel bar member, 52-second steel bar member, 53-third steel bar member. DETAILED DESCRIPTION

[0010] The following is a specific embodiment, and combined with the attached Figure 1-3 It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0011] Example: like Figure 1 , 2 As shown, the present invention discloses a technical solution, a large-section hollow slab beam end shear reinforcement structure, including a hollow slab beam, the hollow slab beam is composed of a hollow slab top surface 1 and a hollow slab bottom surface 2 arranged at intervals from top to bottom, and a hollow slab side surface 3 located between the front and rear sides and between the left and right sides of the hollow slab top surface 1 and the hollow slab bottom surface 2, the hollow slab top surface 1, the hollow slab bottom surface 2 and the hollow slab side surface 3 enclose and form a cavity.

[0012] Brick walls 4 are built at both ends of the reinforcement area in the above-mentioned cavity. In this embodiment, the brick walls 4 are 24 walls or 12 walls, and the reinforcement area is blocked by the brick walls 4 at both ends and the side walls of the hollow slab beam; a support steel bar group 5 is fixed in the reinforcement area, and a groove 6 is formed in the internal space of the support steel bar group 5. A grouting hole is opened on the top surface 1 of the hollow slab, and an air bag 7 is placed in the groove 6, and the air bag 7 is placed in the groove 6 through the grouting hole. Figure 3As shown, the side wall of the airbag 7 is connected to an air pipe 8, and a pressure gauge 9 is installed on the air pipe 8; the first casting layer 10, the second casting layer 11 and the third casting layer 12 are cast in sequence from bottom to top in the reinforcement area.

[0013] The present invention also provides another technical solution, a reinforcement method for a large-section hollow slab beam end shear reinforcement structure, comprising the following steps: S1. During the construction preparation stage, prepare the materials and equipment required for the construction, such as small milling machines, high-pressure water guns, air compressors, air bags, positioning steel bars, self-leveling concrete, grouting materials, C40 waterproof concrete, AC-16C medium-grained modified asphalt concrete, etc., and conduct technical briefings for the construction personnel to ensure that they are familiar with the construction process and technical requirements; first use a small milling machine to mill the bridge deck pavement layer, with a range of 90×100cm, located within the 134cm-234cm area at the bridge end; S2. During the grouting hole opening stage, a 70×80cm hole is opened on the leveling layer, forming a 10cm wide offset with the hole in the asphalt pavement layer, and a 50×60cm hole is opened on the hollow slab, forming a 10cm wide offset with the hole in the leveling layer. When opening the holes, it is important to retain the original steel bars. The staggered design can form a step-like structure, which can increase the bite force between the new and old concrete after pouring the concrete. When the load acts on the beam end, this bite force can better resist the shear force and prevent the concrete interface from sliding or separating, thereby enhancing the reinforcement effect; S3. Construct the enclosure structure, build 12 walls and 24 walls at both ends of the reinforced area in the cavity, with a clear distance of 3m between the two walls, and form a solid and closed space between the two walls and the inner wall of the hollow slab beam to prevent grouting from exploding during grouting; S4, pretreatment stage, use a high-pressure water gun to clean the internal debris in the reinforcement area and wet the inner wall, then spray the concrete interface agent on the inner wall of the hollow slab beam and the inner wall of the brick wall 4 to ensure the combination of new and old concrete. To prevent water accumulation in the hollow slab, holes are drilled in the bottom surface 2 of the hollow slab before cleaning to remove water and debris. The holes on the bottom surface 2 of the hollow slab need to be blocked during the later pouring; S5. Place the support steel bar group 5 and the airbag 7. Install the support steel bar group 5 inside the reinforcement area, then put the airbag 7 into the groove 6 of the support steel bar group 5 from the grouting hole, use an air compressor to inflate the airbag 7 to 2Mpa±0.5Mpa, monitor the air pressure through the pressure gauge 9 to ensure that the airbag 7 forms a stable inner membrane, and stop inflating and tighten the valve at the end of the air pipe 8 after reaching the control pressure value. Observe the pressure gauge reading at any time during the pouring process, and immediately add pressure when the air pressure is insufficient to ensure the construction quality; S6. Concrete pouring: self-leveling concrete should be used. It should have good self-flowing properties, high early strength, no shrinkage, slight expansion and strong bonding ability. The main performance indicators should meet the national standards, strength C50, initial setting time should not exceed 30 minutes, and it should be poured in layers. The first pouring layer 10 is 10cm high. After initial setting, the second pouring layer 1140cm is poured. After initial setting, the third pouring layer 12 is poured to the bottom of the grouting hole; S7, sealing the grouting holes, straightening the original steel bars retained at the grouting holes, binding and welding them, and pouring the grouting material above the top surface 1 of the hollow slab; S8. Bridge deck restoration: According to the bridge deck paving reinforcement diagram, 6 cm thick C40 waterproof concrete is re-paved. After reaching the design strength, 10 cm thick AC-16C medium-grained modified asphalt concrete is paved and compacted with small machinery.

[0014] Specifically, the above-mentioned supporting steel bar group 5 is composed of a first steel bar member 51, a second steel bar member 52 and a third steel bar member 53. The second steel bar member 52 is composed of two parallel transverse steel bars at the upper part and two parallel transverse steel bars at the lower part. The two ends of the transverse steel bars are respectively fixedly connected to the brick walls 4 at the two ends, and the upper transverse steel bars are centrally arranged, and the lower transverse steel bars are distributed to the front and rear sides. The third steel bar member 53 is composed of a plurality of longitudinally arranged longitudinal steel bars. The longitudinal steel bars are evenly distributed along the length direction of the transverse steel bars, and the two ends of the longitudinal steel bars are fixedly connected to the inner wall of the hollow slab beam. The longitudinal steel bars are located above the lower transverse steel bars and are fixedly connected to the lower transverse steel bars. The first steel bar member 51 is composed of a plurality of inverted U-shaped steel bars, and the inverted U-shaped steel bars are evenly distributed along the length direction of the transverse steel bars. The lower part of the inverted U-shaped steel bar is fixedly connected to the lower transverse steel bar, and the upper part of the inverted U-shaped steel bar is fixedly connected to the upper transverse steel bar.

[0015] When placing the support steel bar group 5 in step S5 of the present invention, first, corresponding holes need to be punched on the inner walls of the two brick walls, and then the transverse steel bars are inserted into the holes, and finally they are fixed to the wall with steel nails. Expansion bolts, concrete anchors, etc. can also be used to fix the two ends of the transverse steel bars to the inner walls of the brick walls; then, corresponding holes are punched on the front and rear inner walls of the hollow slab beam, and then the longitudinal steel bars are inserted into the holes, and finally they are fixed to the hollow slab with steel nails, and the longitudinal steel bars are fixedly connected to the lower transverse steel bars by binding welding; finally, the inverted U-shaped steel bars are fixedly connected to the transverse steel bars by binding welding, and the installation of the support steel bar group 5 is now complete.

[0016] The present invention provides a method and structure for shear reinforcement of the ends of large-section hollow slab beams. By pouring concrete through holes in the beam ends, the cross-section of the beam ends is increased, thereby effectively improving the shear bearing capacity of the hollow slab. The reinforcement construction is carried out without interrupting traffic, thereby reducing the impact on traffic. The shape of the hollow slab beam is not changed, and there is no need for embedding reinforcement. The operation is simple and the construction efficiency is high. In addition, an air bag is used as an inner membrane to facilitate construction and ensure the quality of concrete pouring.

[0017] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A large-section hollow slab beam end shear reinforcement structure, comprising a hollow slab beam, wherein the hollow slab beam comprises a hollow slab top surface (1) and a hollow slab bottom surface (2) spaced apart from each other, and a hollow slab side surface (3) located between the front and rear sides and between the left and right sides of the hollow slab top surface (1) and the hollow slab bottom surface (2), wherein the hollow slab top surface (1), the hollow slab bottom surface (2) and the hollow slab side surface (3) enclose and form a cavity, characterized in that: Brick walls (4) are built at both ends of the reinforcement area in the cavity, and the reinforcement area is blocked by the brick walls (4) at both ends and the side walls of the hollow slab beam; a support steel bar group (5) is fixed in the reinforcement area, and a groove (6) is formed in the internal space of the support steel bar group (5); a grouting hole is opened on the top surface (1) of the hollow slab, an air bag (7) is placed in the groove (6), and the air bag (7) is placed in the groove (6) through the grouting hole; the side wall of the air bag (7) is connected to an air pipe (8), and a pressure gauge (9) is installed on the air pipe (8); a first casting layer (10), a second casting layer (11) and a third casting layer (12) are cast in sequence from bottom to top in the reinforcement area.

2. A method for reinforcing a large-section hollow slab beam end shear reinforcement structure according to claim 1, characterized in that: The following steps are involved: S1. During the construction preparation stage, a small milling machine is used to mill the bridge deck pavement layer, with a range of 90×100cm, located in the area of ​​134cm-234cm at the bridge end; S2. During the grouting hole opening stage, a 70×80cm hole is opened on the leveling layer, with a 10cm wide offset between the hole in the asphalt pavement layer and a 50×60cm hole is opened on the hollow slab, with a 10cm wide offset between the hole in the leveling layer and the hole. When opening the hole, pay attention to retaining the original steel bars; S3, constructing a protective structure, building brick walls (4) at both ends of the reinforced area in the cavity, and forming a closed space between the inner wall of the hollow slab beam; S4, pretreatment stage, using a high-pressure water gun to clean the internal debris of the reinforcement area and wet the inner wall, and then spraying a concrete interface agent on the inner wall of the hollow slab beam and the inner wall of the brick wall (4), and drilling holes in the bottom surface of the hollow slab (2) before cleaning; S5, placing the support steel bar group (5) and the air bag (7), installing the support steel bar group (5) inside the reinforcement area, and then placing the air bag (7) into the groove (6) of the support steel bar group (5) from the grouting hole, using an air compressor to inflate the air bag (7) to 2Mpa±0.5Mpa, monitoring the air pressure through a pressure gauge (9) to ensure that the air bag (7) forms a stable inner membrane, and after reaching the control air pressure value, stop inflating and tighten the valve at the end of the air pipe (8); S6, concrete pouring, using self-leveling concrete, strength grade C50, initial setting time not exceeding 30 minutes, pouring in layers, the first pouring layer (10) is 10 cm high, after initial setting, pour the second pouring layer (11) 40 cm high, after initial setting, pour the third pouring layer (12) to the bottom of the grouting hole; S7, sealing the grouting holes, straightening the original steel bars retained at the grouting holes, binding and welding them, and pouring grouting material onto the top surface (1) of the hollow slab; S8. Bridge deck restoration: According to the bridge deck paving reinforcement diagram, 6 cm thick C40 waterproof concrete is re-paved. After reaching the design strength, 10 cm thick AC-16C medium-grained modified asphalt concrete is paved and compacted with small machinery.

3. A method for shear reinforcement of large-section hollow slab beam ends according to claim 2, characterized in that: The supporting steel bar group (5) comprises a first steel bar member (51), a second steel bar member (52) and a third steel bar member (53), the second steel bar member (52) comprising two upper parallel transverse steel bars and two lower parallel transverse steel bars, the two ends of the transverse steel bars being fixedly connected to the brick walls (4) at the two ends respectively, and the upper transverse steel bars being centrally arranged, and the lower transverse steel bars being distributed to the front and rear sides, the third steel bar member (53) comprising a plurality of longitudinally arranged longitudinal steel bars, the longitudinal steel bars being evenly distributed along the length direction of the transverse steel bars, and the two ends of the longitudinal steel bars being fixedly connected to the inner wall of the hollow slab beam, the longitudinal steel bars being located above the lower transverse steel bars and being fixedly connected to the lower transverse steel bars, the first steel bar member (51) comprising a plurality of inverted U-shaped steel bars, and the inverted U-shaped steel bars being evenly distributed along the length direction of the transverse steel bars, the lower part of the inverted U-shaped steel bars being fixedly connected to the lower transverse steel bars, and the upper part of the inverted U-shaped steel bars being fixedly connected to the upper transverse steel bars.

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