A high-performance lightweight connection structure for prefabricated capping beams and bridge piers

Abstract

A high-performance lightweight connection structure for prefabricated capping beams - bridge piers, belonging to the field of bridge structure details, includes a prefabricated capping beam, a bridge pier, and a UHPC cast-in-place joint. The prefabricated capping beam is provided with capping beam connecting steel bars and capping beam reserved holes, the bridge pier is provided with pier top reserved connecting steel bars and pier reserved holes, and the UHPC cast-in-place joint fixedly connects the capping beam - bridge pier by bonding the capping beam connecting steel bars, pier top reserved connecting steel bars, capping beam reserved holes, and pier reserved holes together. The connection structure of the present invention has the advantages of no stirrup connection structure in the UHPC cast-in-place joint segment, clear load transfer path, no welded connection between steel bars, no stress concentration, simple construction, accelerated construction speed, shortened construction period, large connection stiffness, and good durability. It has strong practicability and good economic benefits, and has broad application prospects in the field of bridge prefabrication construction.

Description

Technical Field

[0001] The present invention relates to the field of bridge structure details, and more specifically, to a high-performance lightweight connection structure for precast capping beams and piers. Background Art

[0002] Prefabrication is the main trend of the development of civil engineering in China and also the direction of the vigorous development of bridge engineering. Compared with the traditional cast-in-place bridge construction technology, prefabricated bridge construction has the following advantages: It does not require a large amount of on-site steel bar connection and formwork pouring, which can speed up the construction progress and shorten the construction period; Components are produced on a large scale in factories. Compared with in-situ pouring, various influencing factors in the component production process can be better controlled to ensure the quality of the project structure; Prefabricated components in the factory can reduce the required site for project construction and centrally handle various construction wastes, etc., which is beneficial to environmental protection.

[0003] As one of the key links in bridge prefabrication construction, if the connection construction between the capping beam and the pier can also be prefabricated, only the connection joint needs to be processed, which will be beneficial to shortening the construction period and saving resources. However, this will make the connection problem between the capping beam and the pier particularly prominent. At present, the common connection methods between the capping beam and the pier in engineering are as follows: Cast-in-place connection between the pier and the capping beam; Mortise-and-tenon connection between the pier and the capping beam; Welding connection with internal steel plates; Grouting sleeve connection; Grouting metal bellows connection; Slot connection, etc.

[0004] The connection part between the capping beam and the pier is an important part of the bridge structure. It needs to support the upper structure of the bridge and transfer the load to the foundation. Therefore, the force of the connection structure is relatively complex. Due to the low bonding performance between normal concrete (NC) and steel bars, in order to meet the bearing capacity requirements, the main reinforcement diameter of the pier is usually large, and the connecting steel bars with the capping beam also need a long lap length. If conventional concrete materials are used as the grouting material for the connection between the capping beam and the pier, the lap length is generally greater than 1m. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention discloses a high-performance lightweight connection structure for precast capping beams and piers, providing a connection structure for the connection between the capping beam and the pier that can improve the local compressive strength and stiffness, effectively prevent cracks from occurring at the connection, has good durability, has no stirrups in the connection area, no welding between steel bars, has a simple structure, and is easy to construct.

[0006] To achieve the above object, the present application is realized through the following technical solutions:

[0007] A high-performance lightweight connection structure for precast capping beam - pier, comprising a precast capping beam, a pier and a cast-in-place UHPC joint. The precast capping beam is provided with capping beam connecting steel bars and capping beam reserved holes. The pier is provided with pier top reserved connecting steel bars and pier reserved holes. The cast-in-place UHPC joint bonds the capping beam connecting steel bars, the pier top reserved connecting steel bars, the capping beam reserved holes and the pier reserved holes to fixedly connect the capping beam - pier.

[0008] Preferably, the cast-in-place UHPC joint comprises reactive powder concrete and / or ultra-high performance fiber-reinforced concrete.

[0009] Preferably, the positions of the capping beam reserved holes correspond to those of the pier top reserved connecting steel bars, and the positions of the pier reserved holes correspond to those of the capping beam connecting steel bars.

[0010] Preferably, the capping beam connecting steel bars and the pier top reserved steel bars are respectively inserted into the pier top reserved holes and the capping beam reserved holes.

[0011] Preferably, the connecting length of the capping beam connecting steel bars is more than four times the diameter of the steel bars.

[0012] Preferably, the connecting length of the pier top reserved steel bars is more than 35 cm. The connecting length of the steel bars is short, and the reinforcement ratio in the connecting area is low.

[0013] Preferably, the connection sections of the precast capping beam, the pier and the cast-in-place UHPC joint are all serrated.

[0014] In the technical solution of this application, the bonding force between UHPC (Ultra-High Performance Concrete) and steel bars is stronger than that between ordinary concrete and steel bars. The lap length can be reduced to 35 cm, so the height of the capping beam can be reduced, the structure can be simplified, made lighter, convenient for hoisting, and at the same time, the integrity of the capping beam - pier connection structure can be improved; UHPC has a low porosity and non-connected voids, has strong carbonation resistance, can prevent chloride ion erosion, and its impermeability is much higher than that of ordinary concrete (NC) materials, which can protect the steel bars in the connection structure from corrosion. The durability of the capping beam - pier connection can reach more than 200 years. Moreover, using UHPC to treat the joints can effectively reduce the risk of cracks in the connection area and extend the service life of the connection structure; further, the reserved steel bars at the top of the pier and the connecting steel bars of the capping beam do not need to be welded. Compared with the steel bar welding of the conventional connection structure, the non-welding connection process will not cause stress concentration and the construction is also simpler. There is no stirrup structure in the UHPC cast-in-place joint segment. Compared with the conventional structure, this application makes the structure simple, the load transfer path clear, and the construction convenient; further, the lightweight connection structure can realize the prefabricated construction of the pier - capping beam. The capping beam is prefabricated in the factory and only joint treatment is required on site, which can speed up the construction progress and greatly shorten the construction period; furthermore, the connection sections of the prefabricated capping beam, pier and UHPC cast-in-place joint are all serrated. Compared with the conventional structure, it can effectively increase the shear area and thus improve the shear bearing capacity of the connection surface.

[0015] In summary, compared with the prior art, the obvious advantages of the present invention are:

[0016] (1) It can greatly improve the strength, stiffness and integrity of the capping beam - pier connection, and effectively reduce the risk of cracks in the connection area;

[0017] (2) The UHPC cast-in-place joint has high self-compressive strength, no stirrup connection structure, clear load transfer path, excellent bonding performance between UHPC and steel bars, and no stress concentration phenomenon will occur due to non-welding connection between steel bars;

[0018] (3) Using UHPC as the grouting material to connect the capping beam and the pier, the lap length only needs to be more than 35 cm, which greatly reduces the height of the capping beam, reduces its self-weight, and saves building resources;

[0019] (4) As the main load-bearing member of the bridge superstructure, the structure of the present invention can safely and reliably transfer the loads of the superstructure to the foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the connection structure of the prefabricated capping beam - pier with the UHPC cast-in-place joint of the present invention;

[0021] Figure 2 It is the A - A sectional view of the UHPC cast-in-place joint of the present invention.

[0022] 1. Prefabricated bent cap; 2. Pier; 3. UHPC cast-in-place joint; 4. Bent cap connecting steel bars; 5. Reserved connecting steel bars at the top of the pier; 6. Reserved holes in the bent cap; 7. Reserved holes in the pier. Specific implementation manners

[0023] The present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the raw materials and methods used in the embodiments of the present invention are the raw materials commonly purchased in the market and the methods commonly used in the art.

[0024] Embodiment 1

[0025] As Figure 1 shown, the high-performance lightweight connection structure of the prefabricated bent cap - pier mainly consists of a prefabricated bent cap 1, a pier 2, a UHPC (ultra-high performance concrete) cast-in-place joint 3, bent cap connecting steel bars 4, reserved steel bars 5 at the top of the pier, reserved holes 6 in the bent cap and reserved holes in the pier. The A - A sectional view of the UHPC cast-in-place joint is as Figure 2 shown.

[0026] In this embodiment, the cross-sectional height of the prefabricated bent cap 1 is 45 cm, the width is 120 cm, the cross-sectional diameter of the pier 2 is 120 cm, the lap length of the bent cap connecting steel bars 4 and the top of the pier is 15 cm, the lap length of the reserved steel bars 5 at the top of the pier and the bent cap segment 1 is 35 cm, and the connecting steel bars 4 and the reserved steel bars 5 are respectively made of HRB400 grade steel bars with diameters of 28 mm and 30 mm.

[0027] In this embodiment, the prefabricated bent cap segment 1 is prefabricated and formed with ordinary concrete (NC). The UHPC (ultra-high performance concrete) cast-in-place joint 3 in this embodiment is poured with ultra-high performance fiber-reinforced concrete (generally refers to the concrete prepared based on the principle of maximum packing density and having ultra-high strength, high durability, high toughness, high ductility and good construction technology). Compared with ordinary concrete and high-strength concrete, ultra-high performance concrete is a material with more excellent mechanical properties and durability.

[0028] Embodiment 2

[0029] The assembly principle of the high-performance lightweight connection structure of the prefabricated bent cap - pier disclosed in this embodiment:

[0030] According to the specification requirements, the prefabricated bent cap 1 is prefabricated in the factory, and the bent cap connecting steel bars 4 and the reserved holes 6 in the bent cap are reserved. After reaching the design strength, it is transported to the construction site for waiting for installation; the pier 2 is poured at the construction site, and at the same time, the reserved steel bars 5 and the reserved holes 7 are reserved at the top of the pier.

[0031] Then, use professional hoisting machinery and equipment to lift the capping beam 1, so that the connecting steel bars 4 of the capping beam and the reserved steel bars 5 of the pier are inserted into the reserved holes 7 of the pier and the reserved holes 6 of the capping beam respectively; finally, cast the UHPC (ultra-high performance concrete) joint 3, and carry out the next process after the connection structure reaches the design strength.

[0032] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. A high-performance lightweight connection structure for prefabricated capping beam - pier, comprising a prefabricated capping beam, a pier and a UHPC cast-in-place joint, characterized in that, The precast capping beam is provided with capping beam connecting steel bars and capping beam reserved holes, the pier is provided with pier top reserved connecting steel bars and pier reserved holes, and the UHPC cast-in-place joint bonds the capping beam connecting steel bars, pier top reserved connecting steel bars, capping beam reserved holes and pier reserved holes, so that the capping beam - pier is fixedly connected; the positions of the capping beam reserved holes correspond to those of the pier top reserved connecting steel bars, and the positions of the pier reserved holes correspond to those of the capping beam connecting steel bars; the capping beam connecting steel bars and the pier top reserved connecting steel bars respectively penetrate into the pier top reserved holes and the capping beam reserved holes.

2. The high-performance lightweight connection structure according to claim 1, characterized in that, The UHPC cast-in-place joint comprises reactive powder concrete and / or ultra-high performance fiber reinforced concrete.

3. The high-performance lightweight connection structure according to claim 1, characterized in that, The connecting length of the capping beam connecting steel bars is more than four times the diameter of the steel bars.

4. The high-performance lightweight connection structure according to claim 1, characterized in that, The connecting length of the pier top reserved connecting steel bars is more than 35 cm. The connecting length of the steel bars is short, and the reinforcement ratio in the connecting area is low.

5. The high-performance lightweight connection structure according to claim 1, characterized in that, The connection sections of the precast capping beam, pier and UHPC cast-in-place joint are all serrated.

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