A continuous bridge joint structure and a continuous box girder bridge structure

Abstract

The present invention relates to a continuous bridge joint structure and a continuous box girder bridge, comprising two prefabricated box girders and ultra-high performance concrete cast at the joint between the two prefabricated box girders; characterized in that at the continuous pier, only the top plates of the two prefabricated box girders are connected by cast-in-place ultra-high performance concrete to realize the transformation of the bridge structure from a simply supported to a partially continuous structure; the continuous box girder bridge structure adopts the above-mentioned continuous bridge joint structure. Compared with the prior art, the present invention optimizes the design of the joints on the tops of the piers of the traditional simply supported to continuous structure bridges, and only the top plates need to be connected at the joints, and the cumbersome process of jacking and dismantling after setting up temporary supports is omitted, which greatly reduces the construction difficulty and reduces the volume of concrete cast at the construction site, thereby improving the construction efficiency at the joints and the economy of bridge construction.

Description

Technical Field

[0001] The invention relates to the technical field of bridge engineering, and in particular to a continuous bridge joint structure and a continuous box girder bridge structure. Background Art

[0002] The transformation of a conventional simply supported bridge into a continuous structure system involves system conversion during construction. Temporary supports must be set up on the top of the continuous piers first, and then the temporary supports are removed and replaced with permanent supports after the bridge is transformed into a continuous structure system. In addition, cast-in-place ordinary concrete is usually used at the joints of the continuous pier tops, which requires a large amount of pouring and requires a lot of on-site steel bar welding. The construction process is relatively cumbersome and the construction period is long.

[0003] In order to improve joint performance and construction efficiency, ultra-high performance concrete (UHPC) has been applied to bridge joints. However, the current unit price of UHPC is relatively high. For the commonly used box girder sections with a full span greater than 50m, the beam height is relatively large, the volume of the full section cast at the joint is large, and the cost is relatively high.

[0004] Chinese patent CN108316132A discloses a structure of a simply supported to continuous bridge structure, in which a section of precast beam is arranged on both sides of the continuous pier top, and a spacing is provided between the beam end faces of the precast beams on both sides, characterized in that: at the continuous pier top of the simply supported to continuous structure, only the top plate and the bottom plate of the two sections of precast beams are connected, and the web part of the beam body is not connected, forming a transition from a simply supported state to a continuous state. This patented technology is a small box girder bridge with multiple transverse main beams for a small span. The proportion of live load bending moment is relatively high, and the top plate bending resistance alone cannot meet the force requirements. The top plate needs to be pulled and the bottom plate needs to be compressed to form a moment to resist the negative bending moment of the fulcrum. Therefore, the top plate and the bottom plate of the precast beam need to be connected to meet the force requirements. In addition, the connection structure of this patented technology is a plate-like structure, the connection strength at the joint is relatively weak, and the construction is relatively complicated. Summary of the invention

[0005] The purpose of the present invention is to provide a continuous bridge joint structure and a continuous box girder bridge structure in order to overcome the defects of the above-mentioned prior art, such as large concrete pouring volume, high construction difficulty and low construction efficiency. The present invention provides a continuous bridge joint structure of a part of the structure using cast-in-place ultra-high performance concrete. Through the use of UHPC, the joint design of the top of the pier of the traditional simply supported continuous structure bridge is optimized to the greatest extent under the premise of ensuring the bearing performance of the joint, so as to simplify the construction and improve the construction efficiency and economy. The present invention also provides a continuous box girder bridge of a part of the structure obtained by using the above-mentioned joint structure.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A continuous bridge joint structure comprises two prefabricated box girders and ultra-high performance concrete cast at the joint between the two prefabricated box girders; the structure is characterized in that at the continuous pier, only the top plates of the two prefabricated box girders are connected by cast-in-place ultra-high performance concrete to realize the transformation of the bridge structure from a simply supported state to a partially continuous structure state.

[0008] In a simply supported to continuous bridge, when the span increases, the proportion of the structure's deadweight in the design load increases significantly, the proportion of the second-phase dead load and live load is relatively low, and the pier top joint basically only bears the negative bending moment that may be generated by the second-phase dead load, vehicle live load and other loads. Based on this analysis, the present invention optimizes the design of the pier top joint of the simply supported to continuous bridge, thereby simplifying the construction and improving the construction efficiency and economy.

[0009] Compared with the prior art, the present invention is mainly suitable for large box girders with a span greater than 50m, whose structural deadweight accounts for a high proportion of the total load, and the live load bending moment on the pier top is relatively small. This part of the negative bending moment can be borne by the local structural connection of the top plate, the volume of cast-in-place concrete is smaller, and the construction is fast; the joint of the present invention is a T-shaped structure, and an L-shaped notch is provided on the top plate of the prefabricated box girder to increase the contact surface between the cast-in-place UHPC joint and the prefabricated beam section, so that the internal force transition of the beam section is smooth, the connection strength is improved, and the volume of cast-in-place concrete is further reduced while ensuring the structural performance.

[0010] Furthermore, a notch is provided at the junction of the end face and the upper surface of the top plate of the prefabricated box beam, and the notches of the two prefabricated box beams and the end face of the top plate form a pouring space for pouring ultra-high performance concrete.

[0011] Furthermore, the notch is L-shaped, and the casting space is a T-shaped structure.

[0012] Furthermore, the distance between the top plate end surfaces of the two prefabricated box girders is 30 to 90 cm.

[0013] Furthermore, along the longitudinal direction of the continuous bridge, the width of the casting space is 2 to 4 times, preferably 3 times, the distance between the top plate end surfaces of the two prefabricated box girders.

[0014] Furthermore, the end of the top plate of the prefabricated box girder is a plate-like structure with uniform thickness, the height of the casting space is the same as the thickness of the plate-like structure at the end of the top plate, and the height of the casting space remains unchanged in the transverse direction of the continuous bridge.

[0015] Furthermore, the height of the notch of the top plate is one quarter to one third of the height of the casting space and is not less than 20 cm.

[0016] Furthermore, the prefabricated box girder is a prefabricated full-span box girder.

[0017] The construction method of the above-mentioned continuous bridge joint structure comprises the following steps:

[0018] (S-1) Prefabricate the whole box beam in the factory;

[0019] (S-2) The prefabricated box girder is transported to the bridge site, two rows of permanent supports are placed on the top of the continuous pier in the longitudinal direction of the bridge, and the prefabricated full-span box girder is hoisted so that it is placed on the corresponding supports to form a simply supported state. After it is in place, the formwork of the cast-in-place UHPC joint is installed between the notch and the end face of the top plate of the prefabricated box girder;

[0020] (S-3) After tying the steel bars at the joints and installing the top slab prestressed pipes and steel strands, pour the mixed UHPC into the joint formwork;

[0021] (S-4) UHPC curing: After the joint UHPC reaches the required strength, the formwork is removed and the top plate prestressing tendons are tensioned, completing the construction.

[0022] The present invention also provides a continuous box girder bridge structure adopting the above-mentioned continuous bridge joint structure.

[0023] Furthermore, two rows of permanent supports are arranged on the top of the continuous pier along the longitudinal direction of the continuous bridge, and the prefabricated box girder is supported by the permanent supports in a simply supported state.

[0024] Furthermore, both ends of the prefabricated box beam are provided with end cross beams.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention uses ultra-high performance concrete (UHPC) and its excellent mechanical properties to simplify the pier top joint structure of the traditional simply supported continuous bridge, eliminating the cumbersome process of setting up temporary supports and then lifting and removing them. On the basis of the simply supported beam, only the top plate is connected to form a partially structural continuous bridge, which not only retains the advantages of the traditional simply supported continuous bridge, but also has a simple structure and greatly reduces the difficulty of construction;

[0027] (2) The joints only need to connect the top plate, which greatly reduces the amount of concrete poured on the construction site. In addition, due to the good anchoring performance of UHPC and steel bars, the steel bar layout can be simplified, so the economy is better;

[0028] (3) The notches set on the top plate of the prefabricated full-span box beam increase the contact surface between the UHPC and the prefabricated beam section, improve the connection strength, and facilitate the stress at the joint;

[0029] (4) Due to the early strength characteristics of UHPC, prestressing can generally be done 1 to 5 days after pouring, which can greatly improve the efficiency of joint construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the present invention;

[0031] Figure 2 is a cross-sectional view of the present invention;

[0032] Figure 3 for Figure 2 The cross-sectional view at the middle AA;

[0033] Figure 4 for Figure 2 Sectional view at the middle BB;

[0034] Figure 5 for Figure 2 Cross-section at mid-CC;

[0035] Figure 6 for Figure 2 Sectional view at DD;

[0036] In the figure, 1 is the precast box girder, 2 is the notch, 3 is the ultra-high performance concrete, 4 is the center line of the support, 5 is the manhole, 6 is the permanent support, h1 is the height of the casting space, h2 is the height of the notch, L1 is the distance between the top plate end faces of the two precast box girders, and L2 is the width of the casting space. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0038] Example 1

[0039] A continuous bridge joint structure is a bridge joint structure with a continuous part of the structure using cast-in-place ultra-high performance concrete, such as Figure 1As shown, it includes two prefabricated full-hole box beams 1 and ultra-high performance concrete 3 poured at the joint between the two prefabricated box beams 1. At the continuous pier, the two prefabricated box beams 1 are spaced apart, and the ultra-high performance concrete 3 is cast between the top plates of the prefabricated box beams 1, that is, only the top plates of the two prefabricated box beams 1 are connected at the continuous pier, so that the bridge structure is changed from a simply supported to a partially continuous state of structure. In this embodiment, the prefabricated box beam 1 is a prefabricated full-hole large box beam, and the prefabricated box beam 1 includes a top plate, a middle beam body belly and a bottom plate. The bottom plates of the two prefabricated box beams 1 are provided with a gap. It should be specifically explained here that ultra-high performance concrete (UHPC) has excellent mechanical properties, and has a high bonding strength with the interface of ordinary concrete, and has better anchoring performance with steel bars than ordinary concrete. Therefore, using it in the joint structure of the continuous pier top can optimize the joint design to the greatest extent, and only the top plate is connected on the basis of the simply supported beam to form a partially continuous bridge of structure, simplifying the construction steps, greatly reducing the amount of concrete cast-in-place, thereby reducing the construction difficulty and improving the construction efficiency.

[0040] like Figure 1 and Figure 2 As shown, a notch 2 is provided at the junction of the end face and the upper surface of the top plate of the precast box beam 1. The structure of the notch is L-shaped. The notches 2 of the two precast box beams 1 and the end face of the top plate form a pouring space for pouring ultra-high performance concrete. In this embodiment, the pouring space is a T-shaped structure. The provision of the notch 2 increases the contact surface between the UHPC and the precast beam section, which can smoothly transition the internal force of the beam section, improve the connection strength, and facilitate the stress at the joint. In this embodiment, the spacing L1 between the end faces of the top plates of the two precast box beams is 60 cm; along the longitudinal direction of the continuous bridge, the width L2 of the pouring space is twice the spacing L1 between the end faces of the top plates of the two precast box beams.

[0041] Combination Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, it can be seen that the end of the top plate of the prefabricated box beam 1 is a plate-like structure with uniform thickness, the height h1 of the casting space is the same as the thickness of the plate-like structure at the end of the top plate, and the height h1 of the casting space remains unchanged in the transverse direction of the continuous bridge; in this embodiment, the height h2 of the notch of the top plate is one third of the height h1 of the casting space and is not less than 20 cm. Figure 5 As shown, the notch 2 is arranged along the width direction of the prefabricated box girder and is a through notch.

[0042] In this embodiment, the prefabricated box girder is a prefabricated large box girder with a whole span, and a manhole 5 is provided near the end of the prefabricated box girder 1 .

[0043] The construction method of the above-mentioned continuous bridge joint structure comprises the following steps:

[0044] (S-1) Prefabricate the whole-span large box beam in the factory and store it for 3 months;

[0045] (S-2) The prefabricated beam segments are transported to the bridge site, two rows of permanent supports 6 are placed in the longitudinal direction of the bridge on the top of the continuous pier, and the prefabricated full-hole box beams of each hole are hoisted onto the corresponding supports 6. The support centerline 4 of the prefabricated full-hole box beam is as follows: Figure 1 As shown, a simply supported state is formed, and after being in place, a formwork for cast-in-place ultra-high performance concrete (UHPC) joints is installed between the notch and the top plate end face of the precast box girder;

[0046] (S-3) After tying the steel bars at the joints and installing the top slab prestressed pipes and steel strands, pour the mixed ultra-high performance concrete (UHPC) into the joint formwork;

[0047] (S-4) UHPC curing: When the joint UHPC reaches the required strength, the formwork is removed and the top slab prestressing tendons are tensioned, completing the construction.

[0048] The joint structure has a simple construction process. The technical solution of the present invention simplifies the pier top joint structure of the traditional simply supported bridge to continuous bridge, greatly reduces the construction difficulty, and improves the construction efficiency and economy.

[0049] The above-mentioned continuous bridge joint structure optimizes the design of the joints on the top of the piers of the traditional simply supported to continuous structure bridge. The joints only need to connect the top plates, and the tedious process of setting up temporary supports and then lifting and removing them is eliminated, which greatly reduces the construction difficulty and the amount of concrete poured on the construction site, thereby improving the construction efficiency of the joints and the economy of bridge construction.

[0050] In the continuous box girder bridge structure using the above continuous bridge joint structure, Figure 6 As shown, two rows of permanent supports 6 are arranged on the top of the continuous pier along the longitudinal direction of the continuous bridge. The supports of the prefabricated box girder 1 in the simply supported state are the permanent supports 6, and the prefabricated box girder 1 is designed as a simply supported beam with end cross beams at both ends.

[0051] Example 2

[0052] A continuous bridge joint structure is a continuous bridge joint structure using cast-in-place ultra-high performance concrete for a part of the structure, such as Figure 1 As shown, it includes two precast box beams 1 and ultra-high performance concrete 3 poured at the joint between the two precast box beams 1. At the continuous pier, the two precast box beams 1 are spaced apart, and ultra-high performance concrete 3 is poured between the top plates of the precast box beams 1, that is, only the top plates of the two precast box beams 1 are connected at the continuous pier, so that the bridge structure is changed from a simply supported state to a partially continuous state. Figure 1 and Figure 2As shown, a notch 2 is provided at the junction of the end face and the upper surface of the top plate of the precast box beam 1. The notches 2 of the two precast box beams 1 and the end face of the top plate form a pouring space for pouring ultra-high performance concrete. In this embodiment, the pouring space is a T-shaped structure. The provision of the notch 2 increases the contact surface between the UHPC and the precast beam section, which can smoothly transition the internal force of the beam section, improve the connection strength, and facilitate the stress at the joint. In this embodiment, the spacing L1 between the end faces of the top plates of the two precast box beams is 30 cm; along the longitudinal direction of the continuous bridge, the width L2 of the pouring space is 4 times the spacing L1 between the end faces of the top plates of the two precast box beams.

[0053] Combination Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, it can be seen that the end of the top plate of the prefabricated box girder 1 is a plate-like structure with uniform thickness, the height h1 of the casting space is the same as the thickness of the plate-like structure at the end of the top plate, and the height h1 of the casting space remains unchanged in the transverse direction of the continuous bridge; in this embodiment, the height h2 of the notch of the top plate is one third of the height h1 of the casting space, and is not less than 20 cm.

[0054] Example 3

[0055] A continuous bridge joint structure is a continuous bridge joint structure using cast-in-place ultra-high performance concrete for a part of the structure, such as Figure 1 As shown, it includes two precast box beams 1 and ultra-high performance concrete 3 poured at the joint between the two precast box beams 1. At the continuous pier, the two precast box beams 1 are spaced apart, and ultra-high performance concrete 3 is poured between the top plates of the precast box beams 1, that is, only the top plates of the two precast box beams 1 are connected at the continuous pier, so that the bridge structure is changed from a simply supported state to a partially continuous state. Figure 1 and Figure 2 As shown, a notch 2 is provided at the junction of the end face and the upper surface of the top plate of the precast box beam 1. The notches 2 of the two precast box beams 1 and the end face of the top plate form a pouring space for pouring ultra-high performance concrete. In this embodiment, the pouring space is a T-shaped structure. The provision of the notch 2 increases the contact surface between the UHPC and the precast beam section, which can smoothly transition the internal force of the beam section, improve the connection strength, and facilitate the stress at the joint. In this embodiment, the spacing L1 between the end faces of the top plates of the two precast box beams is 90 cm; along the longitudinal direction of the continuous bridge, the width L2 of the pouring space is 4 times the spacing L1 between the end faces of the top plates of the two precast box beams.

[0056] Combination Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, it can be seen that the end of the top plate of the prefabricated box girder 1 is a plate-like structure with uniform thickness, the height h1 of the casting space is the same as the thickness of the plate-like structure at the end of the top plate, and the height h1 of the casting space remains unchanged in the transverse direction of the continuous bridge; in this embodiment, the height h2 of the notch of the top plate is one quarter of the height h1 of the casting space, and is not less than 20 cm.

[0057] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A continuous bridge joint structure, comprising two prefabricated box girders (1) and ultra-high performance concrete (3) poured at the joint between the two prefabricated box girders (1); characterized in that: At the continuous pier, only the top plates of two prefabricated box girders (1) are connected by cast-in-place ultra-high performance concrete (3) to change the bridge structure from a simply supported state to a partially continuous structure; A notch (2) is provided at the junction of the end face and the upper surface of the top plate of the prefabricated box beam (1); the notches (2) of the two prefabricated box beams (1) and the end face of the top plate form a pouring space for pouring ultra-high performance concrete (3); the notch is L-shaped, and the pouring space is a T-shaped structure; The height (h2) of the notch of the top plate is one quarter to one third of the height (h1) of the casting space and is not less than 20 cm.

2. A continuous bridge joint structure according to claim 1, characterized in that: The distance (L1) between the top plate end faces of two prefabricated box girders is 30 to 90 cm.

3. The continuous bridge joint structure according to claim 1, characterized in that: Along the longitudinal direction of the continuous bridge, the width (L2) of the casting space is 2 to 4 times the distance (L1) between the top plate end surfaces of the two prefabricated box girders.

4. The continuous bridge joint structure according to claim 1, characterized in that: The end of the top plate of the prefabricated box girder (1) is a plate-like structure with uniform thickness, the height (h1) of the casting space is the same as the thickness of the plate-like structure at the end of the top plate, and the height (h1) of the casting space remains unchanged in the transverse direction of the continuous bridge.

5. A continuous box girder bridge structure, characterized in that: The continuous bridge joint structure as claimed in claim 1 is adopted.

6. A continuous box girder bridge structure according to claim 5, characterized in that: Two rows of permanent supports (6) are arranged on the top of the continuous pier along the longitudinal direction of the continuous bridge, and the prefabricated box girder (1) is supported by the permanent supports (6) in a simply supported state.

7. The continuous box girder bridge structure according to claim 5, characterized in that: Both ends of the prefabricated box beam (1) are provided with end cross beams.

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