A bridge structure with low shrinkage in negative bending moment area and construction method thereof

Abstract

The present invention discloses a low-shrinkage bridge structure in a negative bending moment area and a construction method thereof. The basic filling of the joints can be completed by prefabricated core blocks, thereby reducing the casting of concrete. Since the core blocks are prefabricated structures, the shrinkage effect of concrete has been basically eliminated, reducing the risk of cracking due to the concrete itself. Ultra-high performance concrete is cast in place between the joints and the core blocks, so that the quality of the joints can be guaranteed with only a small amount of ultra-high performance concrete, which is economical and reliable. In addition, at least one layer of first steel bars is embedded in the core blocks along the length direction of the bridge, and multiple layers of second steel bars are embedded in the corresponding positions in the composite beams along their own length direction. When the core blocks are placed in the joints, the second steel bars can be mechanically connected or welded to the first steel bars, thereby ensuring the stress-bearing performance of the core blocks and ensuring the safety of the overall structure of the bridge. The present invention aims to solve the technical problem that shrinkage cracking is prone to occur in existing joint structures in negative bending moment areas.

Description

Technical Field

[0001] The present invention relates to the field of bridges, and in particular to a bridge structure with low shrinkage in a negative bending moment zone and a construction method thereof. Background Art

[0002] Currently, the conventional approach to treating negative bending moments in concrete bridge structures is to first reserve joints and then cast concrete in situ. This approach requires a large amount of cast-in-situ concrete, and the stress state in the negative bending moment zone is significantly affected by the quality of the concrete poured on-site. Furthermore, the shrinkage effect of cast-in-situ concrete can cause cracks in the concrete at the pier top, compromising the safety and durability of the structure.

[0003] To improve shrinkage, some construction companies have adopted the solution of replacing cast-in-place concrete with cast-in-place UHPC (ultra-high performance concrete). However, this will lead to a large demand for UHPC and significantly increase the project cost.

[0004] In view of this, it is necessary to propose a bridge structure with low shrinkage in the negative bending moment area and a construction method thereof to overcome or at least alleviate the above-mentioned defects. Summary of the Invention

[0005] The main purpose of the present invention is to provide a bridge structure with low shrinkage in the negative bending moment area and a construction method thereof. The bridge structure and construction method are intended to solve the technical problem that the existing joint structure in the negative bending moment area is prone to shrinkage cracking.

[0006] To achieve the above-mentioned object, the present invention provides a bridge structure with low shrinkage in a negative bending moment zone, the bridge structure comprising: a composite beam overlapped on a bridge pier, the composite beam being provided with a T-shaped cross-section joint in a negative bending moment zone formed at the bridge pier, the composite beam comprising a left main beam prefabricated on the left side of the joint and a right main beam prefabricated on the right side of the joint, wherein the bridge structure further comprises:

[0007] At least one core block is disposed in the joint, each core block comprising a transverse block and a longitudinal block connected to the transverse block, the transverse block and the longitudinal block forming a T-shaped structure that cooperates with the joint; at least one layer of first steel bars is embedded in the core block along the length direction of the bridge, the first steel bar comprising a first load-bearing section extending from the core block and into the joint; the length of the first load-bearing section is greater than 5 times the diameter of the first steel bar and less than the distance between the surface of the first load-bearing section extending from the core block to the composite beam; shear steel bars are embedded in the core block along the longitudinal direction;

[0008] At least one layer of second steel bars is embedded in each of the left main beam and the right main beam along the length of the bridge; the second steel bars include a second load-bearing section extending from the left main beam or the right main beam and extending into the joint to cooperate with the first load-bearing section; the length of the second load-bearing section is greater than 5 times the diameter of the second steel bar and less than the distance between the surface of the second load-bearing section extending from the left main beam or the right main beam and the core block;

[0009] A casting layer is formed by casting ultra-high performance concrete in a gap formed between the core block and the joint to wrap the first load-bearing section and the second load-bearing section and connect the core block and the composite beam into one.

[0010] Preferably, the shear steel frame includes multiple rows of rectangular steel frames, the shear steel frame penetrates the longitudinal block in the longitudinal direction and is cast in the core block; one end of the shear steel frame extends from the free end of the longitudinal block into the joint and is cast in the casting layer; the other end of the shear steel frame is cast in the transverse block.

[0011] Preferably, all surfaces of the core block except the upper top surface are burred surfaces.

[0012] Preferably, the number of layers of the first steel bars and the second steel bars are both 2; one layer of the first steel bars is cast in the transverse block, and the other layer of the first steel bars is cast in the longitudinal block; the second steel bars are cast in the left main beam and the right main beam at a height position corresponding to the two layers of the first steel bars.

[0013] Preferably, the core block also includes a positioning block, which is arranged on the free end of the longitudinal block; the positioning block abuts against the bottom of the joint so that the sum of the heights of the longitudinal block and the positioning block is greater than the distance between the stepped surface of the joint and the bottom of the joint.

[0014] Preferably, there are a plurality of core blocks, and the plurality of core blocks are arranged at intervals in the joint, and the gaps between adjacent core blocks are filled with the ultra-high performance concrete to form a part of the casting layer.

[0015] In addition, the present invention also provides a joint construction method for the bridge structure with low shrinkage in the negative bending moment area as described above, comprising the following steps:

[0016] The composite beam is prefabricated by tying and embedding the second steel bars in a composite beam casting template, and then pouring concrete to prefabricate the composite beam;

[0017] Pre-tying the first steel bars and the shear steel frame in the core block casting template, and then pouring concrete to prefabricate the core block;

[0018] Positioning and splicing the two composite beams at the bridge pier, so that the splicing of the two composite beams forms the T-shaped joint;

[0019] placing the core block into the joint, and performing tack welding or binding on the first load-bearing section and the second load-bearing section;

[0020] Ultra-high performance concrete is poured in situ between the joint and the core block until the gap between the joint and the core block is filled to form the casting layer.

[0021] Preferably, the method further comprises the step of roughening all surfaces of the core block except the top surface.

[0022] Preferably, the method further includes the steps of: pre-positioning a steel main beam located below the concrete bridge deck of the composite beam in the composite beam casting template; wherein the steel main beam includes an I-beam and an end-bearing steel plate connected to the end of the I-beam, and the end-bearing steel plate is parallel to the width direction of the bridge.

[0023] Preferably, the method further comprises the step of welding a plurality of stud connectors on the end bearing steel plate, wherein the stud connectors are perpendicular to the end bearing steel plate.

[0024] In the solution of the present application, the basic filling of the joints can be completed by prefabricated core blocks, thereby reducing the pouring of concrete. Since the core blocks are prefabricated structures, the shrinkage effect of concrete has been basically eliminated, reducing the risk of cracking due to the concrete itself. Ultra-high performance concrete (UHPC) is cast in place between the joints and the core blocks, so that the quality of the joints can be guaranteed with only a small amount of ultra-high performance concrete (UHPC), which is economical and reliable. In addition, at least one layer of first steel bars is embedded in the core blocks along the length of the bridge, and multiple layers of second steel bars are embedded in the corresponding positions of the composite beams along their own length. When the core blocks are placed in the joints, the second steel bars can be mechanically connected or welded to the first steel bars, thereby ensuring the stress performance of the core blocks and the safety of the overall structure of the bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0026] Figure 1 is a schematic cross-sectional view of a bridge structure along the length direction according to an embodiment of the present invention;

[0027] Figure 2 A schematic cross-sectional view of a core block of a bridge structure according to an embodiment of the present invention;

[0028] Figure 3 A schematic cross-sectional view of a composite beam of a bridge structure according to an embodiment of the present invention;

[0029] Figure 4 is a schematic cross-sectional view of a bridge structure along the width direction according to an embodiment of the present invention;

[0030] Figure 5 A schematic cross-sectional view of another embodiment of a core block of a bridge structure according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic cross-sectional view along the length direction of another embodiment of the bridge structure according to the present invention.

[0032] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments.

[0033] Description of Figure Numbers:

[0034] 100-composite beam, 110-joint, 111-step surface;

[0035] 120-second steel bar, 121-second load-bearing section;

[0036] 150-concrete bridge deck, 160-steel main beam;

[0037] 161-I-beam, 162-end bearing steel plate, 163-bolt connector;

[0038] 200-core block, 230-first steel bar, 231 first load-bearing section, 240-shear reinforcement frame;

[0039] 210- horizontal block, 220- vertical block, 250- positioning block;

[0040] 300-casting layer. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0044] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] Please refer to the attached Figure 1 To the attached Figure 3 The present invention provides a bridge structure with low shrinkage in a negative bending moment area, wherein the bridge structure comprises:

[0046] A composite beam 100 is overlapped on a bridge pier. The composite beam 100 is provided with a T-shaped cross-section joint 110 in a negative bending moment zone formed at the bridge pier. The composite beam 100 includes a left main beam prefabricated on the left side of the joint 110 and a right main beam prefabricated on the right side of the joint 110. The bridge structure further comprises:

[0047] At least one core block 200 is disposed within the joint 110. Each core block 200 includes a transverse block 210 and a longitudinal block 220 connected to the transverse block 210. The transverse block 210 and the longitudinal block 220 form a T-shaped structure that cooperates with the joint 110. At least one layer of first steel bars 230 is embedded in the core block 200 along the length of the bridge. The first steel bars 230 include a first load-bearing section 231 that extends from the core block 200 and into the joint 110. The length of the first load-bearing section 231 is greater than five times the diameter of the first steel bar 230 and less than the distance between the surface of the first load-bearing section 231 extending from the core block 200 and the composite beam 100. Shear reinforcement is embedded in the core block 200 along the longitudinal direction.

[0048] At least one layer of second steel bars 120 is embedded in both the left and right main beams along the length of the bridge. The second steel bars 120 include a second load-bearing section 121 extending from the left or right main beam and into the joint 110 to cooperate with the first load-bearing section 231. The length of the second load-bearing section 121 is greater than five times the diameter of the second steel bar 120 and less than the distance between the surface of the second load-bearing section 121 extending from the left or right main beam and the core block 200.

[0049] The casting layer 300 is formed by casting ultra-high performance concrete in the gap formed between the core block 200 and the joint 110 to wrap the first load-bearing section 231 and the second load-bearing section 121, and connect the core block 200 and the composite beam 100 as a whole.

[0050] It should be noted that the bridge structure of the present application is mainly applicable to a spliced ​​bridge structure, and the composite beam 100 is prefabricated in advance and then transported to the bridge pier for splicing. During splicing, the left main beam and the right main beam are placed in the bridge pier to form a T-shaped joint 110.

[0051] The core block 200 is used to complete the basic filling of the joint 110, thereby reducing the amount of concrete cast in place. At least one layer of first steel bars 230 is embedded in the core block 200, and shear steel bars are also embedded in the longitudinal direction. The first steel bars 230 are used to overlap with the second steel bars 120 in the left main beam or the right main beam to resist negative bending moments. The shear steel bars are used to enhance the shear resistance of the core block. Please refer to the attached Figure 4 In practical applications, considering the difficulty of construction and hoisting, multiple small core blocks 200 can be made and filled in sequence.

[0052] During pouring, less ultra-high performance concrete is needed because most of the space in the joint 110 is filled by the core blocks 200. The ultra-high performance concrete can be poured in from the side of the bridge or from the gaps between multiple core blocks 200.

[0053] In the solution of the present application, the basic filling of the joint 110 can be completed by prefabricating the core block 200, thereby reducing the pouring of concrete. Since the core block 200 is a prefabricated structure, the shrinkage effect of concrete has been basically eliminated, reducing the risk of cracking due to the concrete itself. Ultra-high performance concrete (UHPC) is cast in place between the joint 110 and the core block 200, so that the quality of the joint 110 can be guaranteed with only a small amount of ultra-high performance concrete (UHPC), which is economical and reliable. In addition, at least one layer of first steel bars 230 is embedded in the core block 200 along the length direction of the bridge, and multiple layers of second steel bars 120 are embedded in the corresponding position of the composite beam 100 along its own length direction. When the core block 200 is placed in the joint 110, the second steel bars 120 can be mechanically connected or welded to the first steel bars 230, thereby ensuring the stress performance of the core block 200 and ensuring the safety of the overall structure of the bridge.

[0054] As a preferred embodiment of the present invention, the shear reinforcement frame 240 includes multiple layers of rectangular frame-shaped reinforcement frames. A portion of the shear reinforcement frame 240 extends from one end of the longitudinal block 220 away from the transverse block 210 into the joint 110 and is cast in the casting layer 300. The shear reinforcement frame 240 is used to resist shear force and can be composed of multiple layers of frame-shaped reinforcement. The shear reinforcement frame 240 passes through the longitudinal block 220 in the longitudinal direction and is cast in the core block 200. Specifically, one end of the shear reinforcement frame 240 extends from the bottom (free end) of the core block 200, so that after casting, this portion of the shear reinforcement frame 240 is consolidated by concrete, thereby improving the longitudinal connection stability of the core block 200. Furthermore, the other end of the shear reinforcement frame 240 can be cast in the transverse block 210. Being arranged in the transverse block 210 can improve the tightness of the connection between the transverse block 210 and the longitudinal block 220.

[0055] Furthermore, all surfaces of the core block 200 except the top surface are roughened. The top surface is the side of the horizontal block 210 facing away from the vertical block 220. The other surfaces are roughened by a chiseling process to facilitate connection between the core block 200 and the cast-in-place ultra-high performance concrete.

[0056] Preferably, the number of layers of first and second steel bars 230 and 120 is two; one layer of first steel bars 230 is cast in the transverse block 210, and the other layer of first steel bars 230 is cast in the longitudinal block 220. The second steel bars 120 are cast in the left and right main beams at heights corresponding to the two layers of first steel bars 230. Since both the transverse and longitudinal blocks 210 and 220 are provided with first steel bars 230, they cooperate with the corresponding second steel bars 120 to further enhance the compressive strength of the joints and the reliability of the connection.

[0057] Please refer to Figure 5 and Figure 6 As an optional embodiment of the present invention, core block 200 further includes a positioning block 250, which is disposed on the end of longitudinal block 220 away from transverse block 210. Positioning block 250 abuts the bottom of joint 110, such that the sum of the heights of longitudinal block 220 and positioning block 250 is greater than the distance between the stepped surface 111 of joint 110 and the bottom of joint 110. This embodiment addresses the situation where only one core block 200 is used. When a single, large core block 200 is used for filling, to prevent the casting gap on the bridge surface from being completely covered, a positioning block 250 is disposed at the bottom of core block 200, such that the sum of the heights of longitudinal block 220 and positioning block 250 is greater than the distance between the stepped surface 111 of joint 110 and the bottom of joint 110. This allows concrete to be poured between transverse block 210 and the stepped surface 111 of joint 110. The shape of the positioning block 250 is not particularly limited and may be a rectangular block or a trapezoidal block, as long as it can stably support the vertical block 220 .

[0058] As another optional embodiment of the present invention, please refer to the attached Figure 4 The number of core blocks 200 can also be multiple, and multiple core blocks 200 are placed in the joint 110 at intervals. The gaps between adjacent core blocks 200 are filled with ultra-high performance concrete, forming part of the casting layer 300. Prefabricating multiple core blocks 200 can reduce the difficulty of construction and hoisting.

[0059] As a specific embodiment of the present invention, a composite beam 100 includes a concrete bridge deck 150 and a steel main beam 160 (primarily an I-beam 161) disposed beneath the concrete bridge deck 150. The ends of the composite beam 100 are stepped, forming a joint 110 between adjacent composite beams 100. The concrete bridge deck 150 and the steel main beam 160 disposed beneath the concrete bridge deck 150 form a steel-concrete composite beam. The stepped ends of the composite beam 100 allow for the formation of the joint 110 when joined. The transverse groove of the joint 110 is located in the concrete bridge deck 150, while the longitudinal groove of the joint 110 is primarily located in the steel main beam 160.

[0060] Furthermore, the core block 200 and the concrete bridge deck 150 are made of the same type of concrete. The core block 200 and the concrete bridge deck 150 are made of the same type of concrete to better bond them together, thereby avoiding shrinkage or other quality defects.

[0061] Furthermore, the steel main beam 160 comprises an I-beam 161 and an end-bearing steel plate 162 connected to the end of the I-beam 161. The end-bearing steel plate 162 is parallel to the width of the bridge. Multiple stud connectors 163 can be provided on the end-bearing steel plate 162. These stud connectors 163 ensure a stronger bond between the steel main beam 160 and the UHPC, preventing interlayer slippage. Furthermore, the end-bearing steel plate 162 also serves as a casting formwork.

[0062] In addition, the present invention also provides a joint construction method for the bridge structure with low shrinkage in the negative bending moment area as described above, comprising the following steps:

[0063] S10, pre-binding and embedding second steel bars 120 in the composite beam casting template, and pouring concrete to prefabricate the composite beam 100;

[0064] A prefabricated composite beam 100, wherein the end of the composite beam 100 is stepped, and the composite beam is embedded with at least one layer of second steel bars 120 along its length, and the second steel bars 120 include a second load-bearing section 121 extending from the composite beam;

[0065] Specifically, composite beam 100 may include a concrete deck 150 and a steel main beam 160 (primarily an I-beam 161) disposed below the concrete deck 150. The concrete deck 150 and the steel main beam 160 disposed below the concrete deck 150 form a steel-concrete composite beam. The ends of the composite beam are stepped to form a joint 110 when spliced ​​together. The transverse groove of joint 110 is located in the concrete deck 150, while the longitudinal groove of joint 110 is mainly located in the steel main beam 160.

[0066] S20, pre-binding the first steel bars 230 and the shear reinforcement frame 240 in the core block casting template, and pouring concrete to prefabricate the core block 200;

[0067] A prefabricated core block 200 includes a transverse block 210 and a longitudinal block 220 connected to the transverse block 210. The transverse block 210 and the longitudinal block 220 form a T-shaped structure that matches the joint 110. At least one layer of first steel bars 230 is embedded in the core block 200 along the length of the bridge. The first steel bars 230 include a first load-bearing section 231 that extends from the core block 200 and into the joint 110. A shear reinforcement frame 240 longitudinally penetrates the longitudinal block 220 and is cast within the core block 200. Specifically, one end of the shear reinforcement frame 240 extends from the bottom (free end) of the core block 200 so that after casting, this portion of the shear reinforcement frame 240 is cemented with concrete, thereby improving the longitudinal connection stability of the core block 200. The other end of the shear reinforcement frame 240 can be cast within the transverse block 210. Being disposed within the transverse block 210 can improve the tightness of the connection between the transverse block 210 and the longitudinal block 220.

[0068] S30, positioning and splicing the two composite beams 100 at the bridge pier, forming a T-shaped joint 110 at the splicing point of the two composite beams 100;

[0069] S40, placing the core block 200 into the joint 110, and performing positioning welding or binding on the first force-bearing section 231 and the second force-bearing section 121;

[0070] The length of the first load-bearing section 231 satisfies the following requirements: greater than 5 times the diameter of the first steel bar 230 and less than the distance between the surface of the first load-bearing section 231 extending out of the core block 200 and the composite beam 100; the length of the second load-bearing section 121 satisfies the following requirements: greater than 5 times the diameter of the second steel bar 120 and less than the distance between the surface of the second load-bearing section 121 extending out of the composite beam and the core block 200;

[0071] S50 , ultra-high performance concrete is poured between the joint 110 and the core block 200 until the gap between the joint 110 and the core block 200 is filled to form a pouring layer 300 .

[0072] After the core block 200 is placed, ultra-high performance concrete (UHPC) is cast in situ between the joint 110 and the core block 200, so that the quality of the joint 110 can be guaranteed with only a small amount of ultra-high performance concrete (UHPC), which is economical and reliable.

[0073] In the solution of the present application, the basic filling of the joint 110 can be completed by prefabricating the core block 200, thereby reducing the pouring of concrete. Since the core block 200 is a prefabricated structure, the construction quality can be reliably guaranteed, and the shrinkage effect of the concrete has been basically eliminated, reducing the risk of cracking due to the concrete itself. Ultra-high performance concrete (UHPC) is cast in place between the joint 110 and the core block 200, so that the quality of the joint 110 can be guaranteed with only a small amount of ultra-high performance concrete (UHPC), which is economical and reliable. In addition, at least one layer of first steel bars 230 is embedded in the core block 200 along the length direction of the bridge, and multiple layers of second steel bars 120 are embedded in the corresponding position of the composite beam 100 along its own length direction. When the core block 200 is placed in the joint 110, the second steel bars 120 can be mechanically connected or welded to the first steel bars 230, thereby ensuring the stress performance of the core block 200 and ensuring the safety of the overall structure of the bridge.

[0074] Preferably, all surfaces of the core block 200 except the top surface are roughened. The top surface is the side of the horizontal block 210 facing away from the vertical block 220. The other surfaces are roughened to obtain burrs, thereby facilitating connection between the core block 200 and the cast-in-place ultra-high performance concrete.

[0075] Preferably, the joint construction method also includes the steps of: pre-positioning a steel main beam 160 located below the concrete bridge deck 150 of the composite beam 100 in the composite beam casting template; wherein the steel main beam 160 includes an I-beam 161 and an end-bearing steel plate 162 connected to the end of the I-beam 161, and the end-bearing steel plate 162 is parallel to the width direction of the bridge.

[0076] In this embodiment, the composite beam includes a concrete deck 150 and a steel main beam 160 (primarily an I-beam 161) disposed below the concrete deck 150. When casting the composite beam 100, the steel main beam 160, located below the concrete deck 150 of the composite beam 100, is first pre-positioned within the composite beam casting formwork. The concrete deck 150 and the steel main beam 160 disposed below the concrete deck 150 form a steel-concrete composite beam, and the ends of the composite beam are stepped to form a joint 110 when spliced ​​together. The transverse groove of the joint 110 is located in the concrete deck 150, and the longitudinal groove of the joint 110 is mainly located in the steel main beam 160. The end bearing steel plate 162 can serve as a casting formwork.

[0077] Preferably, the joint construction method further comprises the step of welding a plurality of stud connectors 163 on the end bearing steel plate 162, wherein the stud connectors 163 are perpendicular to the end bearing steel plate.

[0078] In this embodiment, a plurality of stud connectors 163 may be provided on the end bearing steel plate 162 . The stud connectors 163 can make the steel main beam 160 and the UHPC bond more firmly, thereby avoiding interlayer slippage.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A bridge structure with low shrinkage in a negative bending moment area, the bridge structure comprising a composite beam overlapped on a bridge pier, the composite beam being provided with a T-shaped cross-section joint in the negative bending moment area formed at the bridge pier, the composite beam comprising a left main beam prefabricated on the left side of the joint and a right main beam prefabricated on the right side of the joint; the composite beam comprising a concrete bridge deck and a steel main beam disposed below the concrete bridge deck; the transverse groove of the joint being located in the concrete bridge deck, and the longitudinal groove of the joint being mainly located in the steel main beam; the bridge structure is characterized in that: The bridge structure further comprises: At least one core block is disposed in the joint; each core block includes a transverse block and a longitudinal block connected to the transverse block, the transverse block and the longitudinal block forming a T-shaped structure, and the T-shaped structure cooperates with the joint; at least one layer of first steel bars is embedded in the core block along the length direction of the bridge, the first steel bar includes a first load-bearing section extending from the core block and into the joint; the length of the first load-bearing section is greater than 5 times the diameter of the first steel bar and less than the distance between the surface of the core block and the composite beam; shear steel bars are embedded in the core block along the longitudinal direction; at least one layer of second steel bars embedded in the left main beam and the right main beam along the length of the bridge; the second steel bars include a second load-bearing section extending from the left main beam or the right main beam, the second load-bearing section extending into the joint and connected to the first load-bearing section; the length of the second load-bearing section is greater than 5 times the diameter of the second steel bar and less than the distance between the surface of the left main beam or the right main beam and the core block; and Casting layer; the casting layer is formed by casting ultra-high performance concrete in the gap formed between the core block and the joint to wrap the first load-bearing section and the second load-bearing section and connect the core block and the composite beam into one; Among them, the shear steel bar is a shear steel bar frame, which penetrates the longitudinal block in the longitudinal direction and is cast in the core block; one end of the shear steel bar frame extends from the free end of the longitudinal block into the joint and is cast in the casting layer; the other end of the shear steel bar frame is cast in the transverse block.

2. The bridge structure with low contraction in the negative bending moment area according to claim 1, characterized in that: All surfaces of the core block except the upper top surface are burred surfaces.

3. The bridge structure with low contraction in the negative bending moment area according to claim 1, characterized in that: The number of layers of the first and second steel bars is two; one layer of the first steel bars is cast in the transverse block, and the other layer of the first steel bars is cast in the longitudinal block; the second steel bars are cast in the left main beam and the right main beam at heights corresponding to the two layers of the first steel bars; The core block also includes a positioning block, which is arranged on the free end of the longitudinal block; the positioning block abuts against the bottom of the joint so that the sum of the heights of the longitudinal block and the positioning block is greater than the distance between the step surface of the joint and the bottom of the joint; there are multiple core blocks, and the multiple core blocks are arranged at intervals in the joint, and the gaps between adjacent core blocks are filled by casting the ultra-high performance concrete to form part of the casting layer.

4. A construction method for a bridge structure with low shrinkage in a negative bending moment zone as claimed in any one of claims 1 to 3, characterized in that: include: The second steel bars are pre-bundled and embedded in the composite beam casting template, and the composite beam is prefabricated after concrete is cast; a steel main beam located below the concrete bridge deck of the composite beam is pre-positioned in the composite beam casting template; wherein the steel main beam includes an I-beam and an end bearing steel plate connected to the end of the I-beam, the end bearing steel plate being parallel to the width direction of the bridge; a plurality of bolt connectors are welded to the end bearing steel plate, the bolt connectors being perpendicular to the end bearing steel plate; The first steel bars and the shear steel frame are pre-tied in the core block casting template, and the core block is prefabricated after concrete is poured; and all surfaces of the core block except the top surface are roughened; Positioning and splicing the two composite beams at the bridge pier, so that the splicing of the two composite beams forms the T-shaped joint; placing the core block into the joint, and performing tack welding or binding on the first load-bearing section and the second load-bearing section; Ultra-high performance concrete is poured in situ between the joint and the core block until the gap between the joint and the core block is filled to form the casting layer.

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