Negative moment zone uplift non-shear prefabricated composite beam and construction method thereof

Abstract

The application provides a negative bending moment area anti-pulling and non-shear prefabricated composite beam and a construction method thereof, the prefabricated beam section is used in the negative bending moment area of a continuous beam bridge, slippage and anti-pulling of a main beam and a concrete slab are realized through a sliding module, the prefabricated beam section comprises a steel beam, a prefabricated concrete slab and a sliding module, and the sliding module is composed of a T-shaped connecting piece and a T-shaped track slot.In the negative bending moment area of a steel-concrete continuous composite beam bridge, the composite beam can release the constraint between the concrete slab and the steel beam through bidirectional slippage, avoid the generation of larger tensile stress due to the cooperative deformation of the concrete slab and the steel beam, improve the longitudinal prestress introduction degree of the concrete slab, effectively improve the long-term performance and durability of the concrete slab, and has the anti-pulling effect, so that the separation of the concrete slab and the steel beam can be prevented.Meanwhile, the composite beam can be prefabricated in a factory to realize standardized production, splicing is carried out according to actual requirements at a construction site, the structure is simple, construction is fast, stress is reasonable, and good technical and economic benefits are obtained.

Description

Technical Field

[0001] This invention relates to a precast bridge structure, belonging to the field of bridge structure technology, specifically a precast composite beam with tensile strength but not shear strength in the negative bending moment zone and its construction method. Background Technology

[0002] Steel-concrete composite structures typically use shear connectors to link steel beams and concrete slabs into a unified structure that shares the load. Under positive bending moments, the concrete slab is in a state of compression, while the steel beams are in a state of tension, fully utilizing the mechanical properties of both components and improving the structure's stiffness and load-bearing capacity. However, in long-span continuous systems, the composite beam segments near the supports are subjected to negative bending moments. Under these negative bending moments, the concrete slab experiences significant tensile stress, leading to cracking and affecting the structure's durability.

[0003] There are two main methods to solve the problem of cracking in concrete slabs in the negative bending moment zone: one is to apply prestress to the concrete slab, thereby offsetting or reducing the tensile stress generated in the concrete slab during service by pre-applying pressure to the concrete. However, since the shear connectors connect the concrete slab to the steel beam to form a whole, a large part of the prestress is borne by the steel beam, resulting in a low prestress implementation rate. The other method is to apply pull-out resistance but not shear resistance technology, which allows relative movement between the concrete slab and the steel beam under negative bending moment, reducing the tensile stress in the concrete slab caused by the deformation of the steel beam. Moreover, the prestress can be fully applied to the concrete slab, resulting in a high prestress implementation rate and better performance.

[0004] Current tensile-resistant but not shear-resistant technologies mainly use shear connectors made of low-modulus materials, all of which require on-site concrete pouring, making construction complex. Therefore, there is an urgent need to invent a precast composite beam that is easy to construct, can meet standardized production and assembly construction requirements, and is not prone to cracking under negative bending moment, so as to improve the durability of continuous composite beams in the negative bending moment zone of continuous beam bridges. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides a precast composite beam with tensile strength but no shear strength in the negative bending moment zone and its construction method. The steel beam and concrete slab are assembled into a whole through sliding modules, achieving both sliding capability and tensile strength between the two.

[0006] This invention provides a precast composite beam with tensile strength but not shear strength in the negative bending moment zone, comprising steel main beams, crossbeams, a concrete bridge deck, sliding modules, and lifting rings. Several steel main beams are connected by several crossbeams to form a steel beam frame. The sliding module includes T-shaped connectors and T-shaped track grooves. The T-shaped connectors are welded to the steel main beams, and the T-shaped track grooves are anchored to the concrete bridge deck. The T-shaped connectors and T-shaped track grooves are connected in a one-to-one correspondence, allowing the steel main beams to slide along the T-shaped track grooves via the T-shaped connectors.

[0007] The steel beam frame is welded with lifting rings at both ends.

[0008] The T-shaped connectors are welded evenly at a certain interval to the center line of the upper flange of the steel beam.

[0009] This invention also provides a construction method for a precast composite beam that is tensile but not shear-resistant in the negative bending moment zone, comprising the following steps: S1: Factory prefabrication of steel beams and T-shaped connectors, with the T-shaped connectors evenly welded at a certain interval to the center line of the upper flange of the steel beam; S2: The T-shaped track groove is prefabricated in the factory. The T-shaped track groove is assembled with the already welded T-shaped connectors, and sealing plates are welded to both ends of the T-shaped track groove. S3: Weld crossbeams between the main steel beams to form a steel beam frame; S4: Factory-prefabricated concrete slabs are used to integrally cast the T-shaped track groove of the sliding module with the bridge deck reinforcement. S5: Weld lifting rings to both ends of the precast composite beam to facilitate the hoisting of the precast beam segments. These rings will also serve as shear connectors during the later on-site pouring of wet joints for the precast bridge deck.

[0010] In step S2, before assembly, lubricating coating is evenly applied to the outer surface of the T-shaped connector and the inside of the T-shaped track groove.

[0011] In step S4, before pouring concrete, the T-shaped track groove is welded to the structural steel bars of the precast concrete slab, and the lower edge of the web of the T-shaped track groove is flush with the lower edge of the precast concrete slab.

[0012] After assembly is completed in step S5, the precast composite beams that are tensile but not shear-resistant in the negative bending moment zone are transported to the construction site as integral composite beam segments and installed in the negative bending moment zone of the continuous beam bridge.

[0013] The beneficial effects of this invention are as follows: (1) The pull-out but not shear-resistant connector of the present invention provides pull-out resistance in the vertical direction while having a high degree of freedom in the longitudinal sliding direction. It can effectively reduce the tensile stress caused by the deformation of the steel beam in the concrete slab, enhance the prestressing effect of the bridge deck, and effectively improve the crack resistance of the composite beam.

[0014] (2) The sliding module of the present invention uses a T-shaped connector with a shorter longitudinal length. When the beam undergoes a large bending deformation, the T-shaped track groove will also undergo bending moment deformation. Since the T-shaped connector is short in length, it will not get stuck.

[0015] (3) When the sliding module of the present invention is pulled out, there will be no stress concentration in the conventional shear connector. The pull-out force of the T-shaped connector is first transmitted to the T-shaped track groove, and then evenly transmitted to the inside of the concrete slab through the T-shaped track groove, which avoids the generation of concentrated pull-out force in the concrete slab and improves the pull-out resistance of the connector.

[0016] (4) The sliding module of the present invention is arranged in segments, unlike the continuous PBL connector, and will not cause longitudinal splitting effect on the concrete bridge deck.

[0017] (5) The present invention can determine the length of the precast composite beam according to the actual length requirements of the negative bending moment zone of the bridge. Within the precast composite beam, a sliding module is used to achieve pull-out resistance but not shear resistance; at the end of the precast composite beam, the lifting ring above the crossbeam is used as a shear connector, and the crossbeam is used as a wet joint template. The wet joint is poured above the crossbeam to end the pull-out resistance but not shear resistance zone and transition to the combined stress state of the bridge deck and steel beam in the positive bending moment zone.

[0018] (6) The pull-out but not shear-resistant connector of the present invention is adaptable to different main beam forms, and the size and quantity of prefabricated components can also be selected according to the load level and bridge layout.

[0019] (7) All components of the pull-out-resistant but not shear-resistant prefabricated composite beam of the present invention are prefabricated and assembled in the factory. The crossbeams and steel main beams form a steel beam frame with good integrity, which is convenient for hoisting and installation. Compared with the traditional plate beam on-site connection, the construction is more convenient and faster, which meets the prefabrication and standardization requirements of prefabricated bridges. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the prefabricated composite beam component that is resistant to pull-out but not to shear according to the present invention.

[0022] Figure 2 This is a cross-sectional view of the precast composite beam that is tensile-resistant but not shear-resistant according to the present invention.

[0023] Figure 3 This is a schematic diagram of the sliding module assembly of the present invention.

[0024] Figure 4 This is a cross-sectional view of the precast concrete slab of the present invention.

[0025] Figure 5 This is a schematic diagram of the assembled prefabricated composite beam that is resistant to pull-out but not to shear according to the present invention.

[0026] The markings in the diagram are: 1. Steel main beam; 2. Precast concrete slab; 3. T-shaped connector; 4. T-shaped track groove; 5. Crossbeam; 6. Lifting ring. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The present invention provides a precast composite beam that is tensile but not shear-resistant in the negative bending moment zone, such as... Figure 1 and Figure 5 As shown, it mainly includes a steel main beam 1, a precast concrete slab 2, a T-shaped connector 3, a T-shaped track groove 4, and a crossbeam 5.

[0029] like Figure 2 As shown, the steel main beam 1 and the precast concrete slab 2 can be assembled together using T-shaped connectors 3 and T-shaped track grooves 4. Two or more T-shaped connectors 3 and one T-shaped track groove 4 form a sliding module, which can slide relative to each other, as shown. Figure 3 As shown. The T-shaped connector 3 is welded to the steel main beam 1, and the T-shaped track groove 4 is cast into the precast concrete slab 2, as shown. Figure 4 As shown, when subjected to a negative bending moment, the steel main beam 1 and the precast concrete slab 2 can generate relative movement in the longitudinal direction, thereby reducing the tensile stress in the precast concrete slab 2 caused by the bending deformation of the steel main beam 1.

[0030] The construction process of this invention is as follows: 1) Factory prefabricate steel main beam 1 and T-shaped connector 3, and weld the T-shaped connector 3 evenly at a certain interval to the center line of the upper flange of steel beam 1.

[0031] 2) The T-shaped track groove 4 is prefabricated in the factory. The T-shaped track groove 4 is then assembled with the pre-welded T-shaped connector 3, such as... Figure 3 As shown, sealing plates are welded to both ends of the T-shaped track groove 4.

[0032] 3) Weld crossbeams 5 to the ends of each precast steel main beam 1 to form a steel beam frame.

[0033] 4) Factory-cast concrete slab 2: Before pouring concrete, the T-shaped track groove 4 is welded to the structural steel reinforcement of the precast concrete slab 2, ensuring that the lower edge of the web of the T-shaped track groove 4 is flush with the lower edge of the precast concrete slab 2. Figure 4 As shown.

[0034] 5) Weld lifting rings 6 at the upper flange positions of the main beams corresponding to the crossbeams at both ends of the composite beam to facilitate the overall hoisting of the precast beam segments.

[0035] 6) During on-site installation, the precast bridge deck is connected to the bridge deck of other beam segments through wet joints. When pouring the wet joint, the concrete is poured on the crossbeam 5 at the end of the precast slab. The crossbeam 5 serves as the bottom formwork of the wet joint, and the lifting ring 6 serves as the shear connector.

[0036] The precast composite beam with tensile strength but no shear strength in the negative bending moment zone described in this embodiment allows for the selection of component sizes and quantities based on different bridge widths and load levels. Each assembly component is prefabricated, and after assembly, the entire beam is transported to the construction site and connected to other beam segments for rapid bridge construction. The precast composite beam with tensile strength but no shear strength in the negative bending moment zone described in this invention features standardized production steps, effectively solving the problem of concrete slab cracking in the negative bending moment zone while simplifying the design and construction process, thus meeting the prefabrication and standardization requirements of prefabricated bridges.

[0037] The embodiments described in this specification are merely specific implementations of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A precast composite beam with tensile strength but not shear strength in the negative bending moment zone, comprising steel main beams, crossbeams, concrete bridge deck, sliding modules, and lifting rings, wherein a steel beam frame is formed by several crossbeams connected to several steel main beams, characterized in that: The sliding module includes a T-shaped connector and a T-shaped track groove. The T-shaped connector is welded to the steel main beam, and the T-shaped track groove is anchored to the concrete bridge deck. The T-shaped connector and the T-shaped track groove are connected in a one-to-one correspondence. The steel main beam slides along the T-shaped track groove through the T-shaped connector. Alternatively, two or more T-shaped connectors and one T-shaped track groove form a sliding module, and the two slide relative to each other.

2. The precast composite beam with tensile strength but not shear strength in the negative bending moment zone according to claim 1, characterized in that: The steel beam frame is welded with lifting rings at both ends.

3. A precast composite beam with tensile strength but not shear strength in the negative bending moment zone according to claim 1, characterized in that: The T-shaped connectors are welded evenly at a certain interval to the center line of the upper flange of the steel beam.

4. A construction method for a precast composite beam that is tensile-resistant but not shear-resistant in the negative bending moment zone, characterized in that, Includes the following steps: S1: Factory prefabrication of steel beams and T-shaped connectors, with the T-shaped connectors evenly welded at a certain interval to the center line of the upper flange of the steel beam; S2: The T-shaped track groove is prefabricated in the factory. The T-shaped track groove is assembled with the already welded T-shaped connectors, and sealing plates are welded to both ends of the T-shaped track groove. S3: Weld crossbeams between the main steel beams to form a steel beam frame; S4: Factory-prefabricated concrete slabs are used to integrally cast the T-shaped track groove of the sliding module with the bridge deck reinforcement. S5: Weld lifting rings to both ends of the prefabricated composite beam to complete the assembly.

5. The construction method of a precast composite beam with tensile strength but not shear strength in the negative bending moment zone according to claim 4, characterized in that: In step S2, before assembly, lubricating coating is evenly applied to the outer surface of the T-shaped connector and the inside of the T-shaped track groove.

6. The construction method of a precast composite beam with tensile strength but not shear strength in the negative bending moment zone according to claim 4, characterized in that: In step S4, before pouring concrete, the T-shaped track groove is welded to the structural steel bars of the precast concrete slab, and the lower edge of the web of the T-shaped track groove is flush with the lower edge of the precast concrete slab.

7. The construction method of the precast composite beam with tensile strength but not shear strength in the negative bending moment zone according to claim 4, characterized in that: After assembly is completed in step S5, the precast composite beams that are tensile but not shear-resistant in the negative bending moment zone are transported to the construction site as integral composite beam segments and installed in the negative bending moment zone of the continuous beam bridge.

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