Steel-concrete composite beam structure with increased height of steel beam in negative moment area and construction method

Abstract

The present invention relates to a steel-concrete composite beam structure with increased beam height in the negative moment zone and a construction method, which includes the following steps: steel beam processing and manufacturing; welding shear connectors; steel beam erection; constructing a concrete bridge deck; constructing guardrails or crash barriers; constructing the bridge deck pavement. Among them, the beam height of the steel beam is increased upward in the negative moment section, the concrete bridge deck is connected to the steel beam through shear connectors to form a composite beam, and the steel beam in the negative moment zone of the steel-concrete composite beam is embedded in the concrete bridge deck; the concrete bridge deck in the positive moment zone is located above the upper flange of the steel beam, and the concrete bridge deck in the negative moment zone is located below the upper wing plate of the steel beam or wraps the upper flange of the steel beam. The present invention circumvents the weakness of the low tensile strength of the concrete bridge deck in the negative moment zone of the continuous composite beam bridge, and makes full use of the tensile strength of the upper wing plate of the steel beam in the negative moment zone of the continuous beam through structural changes to reduce the tensile stress of the concrete bridge deck, making the force of the composite beam more reasonable, improving the disease conditions in the negative moment zone of the structure, and having good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a steel-concrete composite beam structure with increased height of steel beam in the negative moment area and a construction method thereof. Background Technique

[0002] The steel-concrete composite beam structure combines the advantages of steel and concrete materials. The material utilization is relatively reasonable, the construction speed is fast, and the practicability is strong, so it is widely used in the road and bridge and building fields. However, the concrete in the negative moment area of the composite continuous beam is prone to cracking under tension, resulting in poor durability of the composite beam. At present, there are mainly the following methods to solve this problem: First, change the construction sequence to make the steel beam in the negative moment area fully tensile before constructing the bridge deck to reduce the tensile stress of the bridge deck; Second, increase the reinforcement ratio of the bridge deck structure or use high-performance concrete to control the number and width of cracks; Third, improve the construction process and use methods such as prestressing to reduce or avoid the occurrence of tensile stress in the concrete slab. However, for the method of changing the construction sequence, the concrete bridge deck still bears the adverse effects of most of the long-term loads after the bridge is completed; when methods such as increasing the reinforcement are used alone, they work with cracks for a long time, which has an adverse impact on durability; methods such as applying prestress inevitably also apply additional stress to the shear connectors, which not only increases the burden on the steel beam, but also weakens the effect of the prestress applied to the concrete slab. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a steel-concrete composite beam structure with increased height of steel beam in the negative moment area and a construction method thereof, to avoid the weakness of the low tensile strength of the traditional concrete bridge deck, and to make full use of the tensile strength of the upper flange of the steel beam in the negative moment area of the continuous beam through structural changes, so as to reduce the tensile stress of the concrete bridge deck, make the force of the composite beam more reasonable, and improve the disease situation in the negative moment area of the structure. At the same time, there are two preferred solutions for the concrete bridge deck in the negative moment area. One is to use thin-layer ultra-high performance concrete to combine with the steel beam to jointly bear the force, and give full play to the characteristics of ultra-high performance concrete with high tensile strength and good crack resistance; the other is to use ECC concrete to make the steel beam the main load-bearing member, which overcomes the brittleness and weak tensile properties of traditional concrete and better adapts to the deformation of the steel beam. Both high-performance concretes have the characteristics of light self-weight, good durability and fatigue resistance, and have good application prospects.

[0004] To solve the above technical problems, the technical solution of the present invention is: A steel-concrete composite beam structure with increased height of steel beam in the negative moment area, including a steel beam, a concrete bridge deck and shear connectors, characterized in that: the steel beam extends upward in the negative moment section to increase the beam height, the concrete bridge deck is connected to the steel beam through shear connectors to form a composite beam, and the steel beam in the negative moment area of the steel-concrete composite beam is embedded in the concrete bridge deck.

[0005] Furthermore, the concrete bridge deck in the positive bending moment area of the steel-concrete composite beam is located above the upper flange of the steel beam; the concrete bridge deck in the negative bending moment area of the steel-concrete composite beam is located below the upper flange of the steel beam or wraps the upper flange of the steel beam.

[0006] Furthermore, the length of the increased section of the steel beam height in the negative bending moment area of the steel-concrete composite beam is 0.2 - 0.5 times the length of a single-span bridge (i.e., the length of the bridge opening between adjacent steel beams), and the change in beam height is achieved through a gradually varying beam height, that is, the upper flange of the steel beam in the transition area from the positive bending moment area to the negative bending moment area of the steel-concrete composite beam extends obliquely upward.

[0007] Furthermore, the top plane of the upper flange of the steel beam cross-section in the negative bending moment area is higher than the bottom plane of the concrete bridge deck.

[0008] Furthermore, two layers of steel bar meshes are arranged in the concrete bridge deck, and the steel bar meshes are composed of longitudinal and transverse steel bars at a certain spacing; round holes for the transverse steel bars to pass through are opened in the web of the steel beam in the negative bending moment area of the steel-concrete composite beam, and the positions of the round holes correspond one by one to the transverse steel bars.

[0009] Furthermore, through holes are opened in the upper flange of the gradually varying section of the steel beam height, and the positions of the through holes correspond to the longitudinal steel bars of the concrete bridge deck, and the longitudinal steel bars of the concrete bridge deck penetrate through the through holes in the upper flange of the steel beam.

[0010] Furthermore, the shear connectors in the negative bending moment area of the steel-concrete composite beam are arranged at a certain spacing at the lower part of the upper flange of the steel beam or symmetrically arranged at the upper and lower parts of the upper flange of the steel beam.

[0011] Furthermore, shear connectors are arranged at a certain spacing on the upper and lower surfaces of the upper flange at the gradually varying section of the steel beam height of the steel-concrete composite beam.

[0012] Furthermore, a bridge deck pavement is laid on the concrete bridge deck or the upper flange of the steel beam and the upper part of the concrete bridge deck.

[0013] The construction method of the steel-concrete composite beam structure with the steel beam height increased in the negative bending moment area is carried out according to the following steps:

[0014] S1: Processing and manufacturing of the steel beam: During the construction of the bridge substructure, the processing and manufacturing of the steel beam are carried out simultaneously. The corners of the upper flange of the steel beam at the gradually varying section are smoothly processed to reduce stress concentration; according to the design positions of the longitudinal and transverse steel bars of the concrete bridge deck, round holes and through holes are opened at the web and upper flange of the steel beam corresponding to the steel bars.

[0015] S2: Welding of shear connectors: Shear connectors are welded to the steel beam at a certain spacing, and the shear connectors in the increased height section of the steel beam are welded to the lower part of the upper flange or the upper and lower parts.

[0016] S3: Erection of steel girders: The steel girders are erected by means of hoisting, jacking or towing, and the transverse connection structure between the installed steel girders is installed;

[0017] S4: Use steel formwork or profiled steel sheets as the bottom formwork. The profiled steel sheets can be left without removal after the construction of the concrete bridge deck. The bridge deck reinforcement mesh is tied on the bottom formwork. Note that the transverse reinforcement in the negative moment area needs to penetrate the web of the steel girder, and the longitudinal reinforcement needs to penetrate the upper flange of the variable-height section of the beam height. Then, concrete is poured, and natural curing, standard curing or hot water curing is selected for curing;

[0018] S5: Construct guardrails or crash barriers;

[0019] S6: Construct the bridge deck pavement.

[0020] Compared with the prior art, the present invention has the following beneficial effects: It circumvents the weakness of the low tensile strength of the concrete bridge deck in the negative moment area of the continuous composite beam bridge, and makes full use of the tensile strength of the upper flange of the steel girder in the negative moment area of the continuous beam through structural changes to reduce the tensile stress of the concrete bridge deck, making the force of the composite beam more reasonable and improving the disease conditions in the negative moment area of this structure, and having good application prospects.

[0021] The following further describes the present invention in detail with reference to the drawings and specific embodiments. Description of the Drawings

[0022] Figure 1 It is a schematic cross-bridge section structure diagram of Embodiment 1 of the present invention.

[0023] Figure 2 It is a schematic diagram of the variable-height structure of the steel girder in the negative moment area of Embodiment 1 of the present invention.

[0024] Figure 3 It is a schematic cross-bridge section structure diagram of Embodiment 2 of the present invention.

[0025] Figure 4 It is a schematic diagram of the variable-height structure of the steel girder in the negative moment area of Embodiment 2 of the present invention.

[0026] In the figure: 1 - steel girder, 2-1 - positive moment area concrete bridge deck, 2-2 - negative moment area concrete bridge deck of Embodiment 1, 2-3 - negative moment area concrete bridge deck of Embodiment 2, 3 - shear connectors, 4 - through holes, 5 - round holes. Specific Embodiments

[0027] To make the above features and advantages of the present invention more obvious and understandable, the following specific embodiments are given in conjunction with the drawings and described in detail as follows.

[0028] As Figures 1 to 4As shown in the figure, the steel-concrete composite beam structure with the steel beam height increased in the negative moment area includes a steel beam 1, a concrete bridge deck 2 and shear connectors 3. The steel beam 1 increases its beam height upward in the negative moment section. The concrete bridge deck 2 is connected to the steel beam 1 through the shear connectors 3 to form a composite beam. The steel beam 1 in the negative moment area of the steel-concrete composite beam is embedded in the concrete bridge deck 2.

[0029] In the first embodiment of the present invention, as Figures 1 to 2 shown, the concrete bridge deck 2-1 in the positive moment area is located above the upper flange of the steel beam 1, and the concrete bridge deck 2-2 in the negative moment area is located below the upper flange of the steel beam 1; the shear connectors 3 are arranged at a certain interval on the lower part of the upper flange of the steel beam 1 in the negative moment area and on the upper and lower surfaces of the upper flange at the height transition section of the steel beam 1; a number of circular holes 5 are opened in the web of the steel beam 1 in the negative moment area, and the positions of the circular holes correspond to the transverse steel bars of the concrete bridge deck 2-2. A number of through holes 4 are opened in the upper flange of the height transition section of the steel beam 1, and the positions of the through holes correspond to the longitudinal steel bars of the concrete bridge deck 2-2; the upper and lower layers of steel bar meshes of the concrete bridge deck 2-2 in the negative moment area are both located below the upper flange of the steel beam 1 in the negative moment area.

[0030] In the second embodiment of the present invention, as Figures 3 to 4 shown, the main difference between the second embodiment and the first embodiment is that: the concrete bridge deck 2-3 in the negative moment area wraps the upper flange of the steel beam 1; the shear connectors 3 are arranged at a certain interval on the upper and lower parts of the upper flange of the steel beam 1 in the negative moment area; the upper and lower layers of steel bar meshes of the concrete bridge deck 2-3 in the negative moment area are respectively located above and below the upper flange of the steel beam 1 in the negative moment area.

[0031] As Figures 1 to 4 shown, the construction method of the steel-concrete composite beam structure with the steel beam height increased in the negative moment area includes the following steps:

[0032] S1: Steel beam processing and manufacturing: During the construction of the bridge substructure, the processing and manufacturing of the steel beam are carried out simultaneously. The corners of the upper flange of the height transition section of the steel beam are smoothly processed to reduce stress concentration; according to the design positions of the longitudinal and transverse steel bars of the concrete bridge deck, circular holes and through holes are opened at the web and upper flange of the steel beam corresponding to the steel bars.

[0033] S2: Welding shear connectors: Weld the shear connectors to the steel beam at a certain interval. The shear connectors in the height increased section of the steel beam are welded to the lower part or both the upper and lower parts of the upper flange.

[0034] S3: Steel beam erection: The steel beam is erected by using hoisting, jacking or towing methods, and the transverse connection structure between the steel beams is installed.

[0035] S4: Use steel formwork or profiled steel sheet as the bottom formwork. The profiled steel sheet does not need to be removed after the construction of the concrete bridge deck. Tie the bridge deck reinforcement mesh on the bottom formwork. Note that the transverse reinforcement in the negative moment area needs to penetrate the web of the steel girder, and the longitudinal reinforcement needs to penetrate the upper flange of the beam height transition section. Then pour the concrete, and the curing can be natural curing, standard curing or hot water curing;

[0036] S5: Construct the guardrail or crash barrier;

[0037] S6: Construct the bridge deck pavement.

[0038] In the embodiment of the present invention, there are two preferred schemes for the concrete material of the negative moment area concrete bridge deck 2-2 or 2-3: First, use thin-layer ultra-high performance concrete to combine with the steel girder to jointly bear the load, giving play to the characteristics of ultra-high performance concrete with high tensile strength and good crack resistance; Second, use ECC concrete to make the steel girder the main load-bearing member, overcoming the brittleness and weak tensile properties of traditional concrete and better adapting to the deformation of the steel girder. In addition, both of these high-performance concretes have the characteristics of light self-weight, good durability and fatigue resistance, and have good application prospects.

[0039] The present invention is not limited to the above best implementation manner. Anyone can obtain other various forms of the steel-concrete composite continuous beam structure with the steel girder height increased in the negative moment area and its construction method under the inspiration of the present invention. All equal changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A steel-concrete composite beam structure with the steel beam height increased in the negative moment area, comprising a steel beam, a concrete bridge deck and shear connectors, characterized in that: The steel beam extends upward in the negative moment section to increase the beam height. The concrete bridge deck is connected to the steel beam through shear connectors to form a composite beam. The steel beam in the negative moment area of the steel-concrete composite beam is embedded in the concrete bridge deck. The concrete bridge deck in the positive moment area of the steel-concrete composite beam is located above the upper flange of the steel beam. The concrete bridge deck in the negative moment area of the steel-concrete composite beam is located below the upper flange of the steel beam or wraps the upper flange of the steel beam. The length of the increased section of the steel beam height in the negative moment area of the steel-concrete composite beam is 0.2 to 0.5 times the spacing between adjacent steel beams. The change in beam height is achieved through a gradually changing beam height, that is, the upper flange of the steel beam in the transition area from the positive moment area to the negative moment area of the steel-concrete composite beam extends obliquely upward. The top plane of the upper flange of the steel beam cross-section in the negative moment area is higher than the bottom plane of the concrete bridge deck.

2. The steel-concrete composite beam structure with increased height of steel beam in the negative moment area according to claim 1, characterized in that: Two layers of steel bar meshes are arranged in the concrete bridge deck. The steel bar mesh is composed of longitudinal and transverse steel bars at a certain spacing. Circular holes for the transverse steel bars to pass through are opened in the web of the steel beam in the negative moment area of the steel-concrete composite beam, and the positions of the circular holes correspond to the transverse steel bars one by one.

3. The steel-concrete composite beam structure with the increased height of the steel beam in the negative moment area according to claim 2, characterized in that: Through holes are opened in the upper flange of the gradually changing section of the steel beam height. The positions of the through holes correspond to the longitudinal steel bars of the concrete bridge deck, and the longitudinal steel bars of the concrete bridge deck penetrate through the through holes in the upper flange of the steel beam.

4. The steel-concrete composite beam structure with increased height of the steel beam in the negative moment area according to claim 1, wherein: The shear connectors in the negative moment area of the steel-concrete composite beam are arranged at a certain spacing at the lower part of the upper flange of the steel beam or symmetrically arranged at the upper and lower parts of the upper flange of the steel beam.

5. The steel-concrete composite beam structure with increased height of steel beam in the negative moment area according to claim 1, characterized in that: Shear connectors are arranged at a certain spacing on the upper and lower surfaces of the upper flange at the gradually changing section of the steel beam height of the steel-concrete composite beam.

6. The steel-concrete composite beam structure with increased height of the steel beam in the negative moment area according to claim 1, characterized in that: The concrete bridge deck or the upper flange of the steel beam and the upper part of the concrete bridge deck are paved with bridge deck pavement.

7. Construction method of steel-concrete composite beam structure with increased height of steel beam in negative moment area, characterized in that Adopt the steel-concrete composite beam structure with the steel beam height increased in the negative moment area as described in any one of claims 1-6, and proceed as follows: S1: Processing and manufacturing of the steel beam: During the construction of the bridge substructure, the processing and manufacturing of the steel beam are carried out simultaneously. The corners of the upper flange of the gradually changing section of the steel beam height are smoothly processed to reduce stress concentration. Circular holes and through holes are opened at the web and upper flange of the steel beam corresponding to the steel bars according to the design positions of the longitudinal and transverse steel bars of the concrete bridge deck. S2: Welding of shear connectors: Weld shear connectors on the steel beam at a certain spacing. The shear connectors in the increased height section of the steel beam are welded to the lower part of the upper flange or the upper and lower parts. S3: Erection of the steel beam: The steel beam is erected by using hoisting, jacking or dragging methods, and the transverse connection structure between the steel beams is installed. S4: Use the steel formwork as the bottom formwork, bind the steel bar mesh of the bridge deck on the bottom formwork, pay attention that the transverse steel bars in the negative moment area need to penetrate through the web of the steel beam, and the longitudinal steel bars need to penetrate through the upper flange of the gradually changing section of the beam height, and then pour concrete. The curing can be natural curing, standard curing or hot water curing. S5: Construct the guardrail or crash barrier. S6: Construct the bridge deck pavement.

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