Socket Pier Hierarchical Energy Dissipation Structure and Method Adopting UHPC and ECC Layered Filling

Abstract

The present invention relates to a socket-type pier hierarchical energy dissipation structure filled with UHPC and ECC in layers, which includes a bearing platform and a precast pier column located on the bearing platform. A groove is provided on the upper surface of the bearing platform, and the bottom of the pier column is placed in the groove. A connecting sleeve is reserved at the inner bottom of the pier column. A number of reserved longitudinal bars inside the pier column and a number of reserved steel bars buried in the bearing platform are lapped through the connecting sleeve. The pier column and the bearing platform are tightened by prestressing tendons to ensure the integrity of the precast components and overcome the problem of poor overall stiffness of the connecting sleeve. A layer of UHPC concrete layer is poured on the inner wall of the groove, and the gap between the UHPC concrete layer and the outer wall of the root of the pier column is filled with an ECC concrete layer. The ECC material has low strength but good toughness, and will reach the ultimate load first and produce ductile failure. The UHPC has high strength and will fail after the ECC in the internal plastic hinge area fails, enabling the pier to dissipate energy hierarchically, facilitating the early detection of pier damage for repair, and increasing the safety of the bridge and the portability of repair.

Description

Technical Field

[0001] The present invention relates to a socket - type pier hierarchical energy - dissipation structure and method using UHPC and ECC for layered filling, belonging to the field of bridge engineering. Background Art

[0002] Since ancient times, bridges have not only played the role of transportation hubs in our daily lives but also been related to the economic and friendly exchanges between countries. Therefore, the construction and development of bridges are particularly important. However, currently, the service life of bridges is much shorter than the designed life. Whether due to overloading or factors such as earthquakes, it will cause losses of life and property, affect the progress of rescue work, and some bridges are difficult to repair after being damaged. These problems are gradually being solved with the development of technology. Many scholars have studied various new materials to reinforce or improve the overall performance of bridges, and some have developed assembled self - reset piers to accelerate the construction speed and post - earthquake repair speed, etc., which have created well - being for our human bridge construction and repair.

[0003] However, under the strong influence of earthquakes, bridge facilities will still suffer huge damage or even collapse, and the resulting impact often exceeds the huge financial expenditure required for bridge reconstruction or maintenance. Thus, in the construction of highway transportation in our country, it is necessary to strengthen and improve the seismic capacity of bridges to reduce some losses. Based on this, the present invention provides a socket - type pier hierarchical energy - dissipation structure and method using UHPC and ECC for layered filling to improve the seismic capacity of bridges. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a socket - type pier hierarchical energy - dissipation structure and method using UHPC and ECC for layered filling.

[0005] To solve the above - mentioned technical problem, the technical solution of the present invention is: a socket - type pier hierarchical energy - dissipation structure using UHPC and ECC for layered filling, including a bearing platform and a precast pier column located on the bearing platform. A groove is provided on the upper surface of the bearing platform, and the bottom of the pier column is placed in the groove. A connecting sleeve is reserved inside the pier column, and a number of reserved longitudinal bars inside the pier column are lapped with a number of reserved steel bars buried in the bearing platform through the connecting sleeve. The pier column and the bearing platform are tightened by prestressing tendons; a layer of UHPC concrete layer is poured on the inner wall of the groove, and the gap between the UHPC concrete layer and the outer wall of the root of the pier column is filled with an ECC concrete layer.

[0006] Preferably, the prestressing tendon is an unbonded prestressing tendon.

[0007] Preferably, the reserved steel bars inside the pedestal are L-shaped steel bars, which are fixed in the pedestal. The vertical section of the L-shaped steel bars is fixed in the pedestal in advance by pouring concrete, and partially extends outside the groove of the pedestal. The extended part is overlapped with the longitudinal reinforcement of the pier in the connecting sleeve.

[0008] Preferably, the connecting sleeve is a grouting bellows.

[0009] Preferably, the grouting in the connecting sleeve of the pier column is UHPC concrete.

[0010] A construction method for a socket-type bridge pier graded energy dissipation structure using UHPC and ECC layered filling is carried out in the following steps: 1) prefabricating a bridge pier column and a cap with a groove in a factory, wherein longitudinal reinforcement is reserved in the pier column, a grouting corrugated pipe is pre-embedded at the bottom of the pier column, and a plurality of L-shaped steel bars are reserved for the cap; 2) at the construction site, assembling the pier column and the cap, placing the pier column in the center of the groove, inserting the steel bars partially protruding from the cap groove into the grouting corrugated pipe reserved at the bottom of the pier column, so that the longitudinal reinforcement reserved in the pier column and the cap are aligned with each other. Reinforcement overlap is reserved in the cap; 3) Prestressed tendon fixing anchors are set at the bottom of the cap, and prestressed tendon tensioning anchors are set at the top of the pier, and the prestressed tendons are passed through the prestressed tendon holes of the pier column and the cap to tighten the pier column and the cap; 4) UHPC is poured into the grouting corrugated pipe to complete the overlap of the cap steel bars and the pier column longitudinal bars; 5) First, a layer of UHPC is poured in the groove, and then ECC is poured in the gap between the UHPC and the outer wall of the pier column root to form a whole, completing the final connection between the pier column and the cap.

[0011] Compared with the prior art, the present invention has the following beneficial effects: the present invention has a novel structure, convenient and fast construction, good mechanical properties, safety and reliability. A layer of UHPC is first poured into the groove of the pier, and then ECC is filled, so that the pier dissipates energy in stages, can be not damaged or only slightly damaged in an earthquake, and is easy to repair after the earthquake; UHPC has good toughness, durability and corrosion resistance, and improves the tensile, compressive, bending, shear and impact resistance properties, so that the pier can achieve "no damage in a small earthquake, repairable in a medium earthquake, and not collapsed in a large earthquake" as much as possible in an earthquake to ensure the safety of people's lives and property; at the same time, ECC will be damaged first because of its low strength. When the earthquake level increases, secondary energy dissipation occurs, cracks appear in the plastic hinge area at the bottom of the pier column and it is damaged. If the earthquake level is higher, tertiary energy dissipation occurs, and the steel bars at the bottom of the pier column bend and yield; the prestressed tendons provide self-resetting ability, the residual deformation after the earthquake is small, and the pier can be easily repaired after damage, and the construction is convenient.

[0012] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of an embodiment of the present invention.

[0014] In the figure: 1 - prestressed tendon; 2 - longitudinal reinforcement; 3 - pier column; 4 - connecting sleeve; 5 - ECC concrete layer; 6 - reserved reinforcement; 7 - pile cap; 8 - UHPC concrete layer; 9 - anchor. Specific embodiments

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0016] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0018] As Figure 1 shown, this embodiment provides a socket-type pier hierarchical energy dissipation structure filled with UHPC and ECC in layers, including a pile cap and a precast pier column located on the pile cap. A groove is provided on the upper surface of the pile cap, and the bottom of the pier column is placed in the groove. A connecting sleeve is reserved at the inner bottom of the pier column. A number of reserved longitudinal reinforcements inside the pier column are lapped with a number of reserved reinforcements buried in the pile cap through the connecting sleeve. The pier column and the pile cap are tightened by prestressed tendons to ensure the integrity of the precast components and overcome the problem of poor overall stiffness of the connecting sleeve. A layer of UHPC concrete layer is poured on the inner wall of the groove, and the gap between the UHPC concrete layer and the outer wall of the root of the pier column is filled with an ECC concrete layer. The ECC material has low strength but good toughness and will reach the ultimate load first and produce ductile failure. The UHPC has high strength and will fail after the ECC in the internal plastic hinge area fails, enabling the pier to dissipate energy hierarchically, facilitating the early detection of pier damage for repair, and increasing the safety and repair portability of the bridge. That is, the failure process: first, after the ECC in the internal plastic hinge area fails, cracks appear in the plastic hinge area at the bottom of the pier column, and finally the embedded steel bars at the bottom of the pile cap bend and yield, enabling the pier to dissipate energy hierarchically, facilitating the early detection of pier damage for repair, and increasing the safety and convenience of repair of the bridge.

[0019] In the embodiment of the present invention, the prestressed tendon is an unbonded prestressed tendon.

[0020] In an embodiment of the present invention, the reserved steel bars inside the pedestal are L-shaped steel bars, which are fixed in the pedestal. The vertical section of the L-shaped steel bars is fixed in the pedestal by pouring concrete in advance, and partially extends outside the groove of the pedestal. The extended part is overlapped with the longitudinal reinforcement of the pier in the connecting sleeve.

[0021] In the embodiment of the present invention, the connecting sleeve is a grouting bellows. A hole is opened in the side wall of the metal grouting bellows, and then the grouting pipe and the grouting pipe are welded at the hole, and the grouting pipe and the grouting pipe are buried in the cap, which is convenient for grouting after the steel bars are overlapped, and the grouting bellows has high rigidity, high fault tolerance when the steel bars are overlapped, and is convenient for construction.

[0022] In the embodiment of the present invention, the grouting in the connection sleeve of the pier column is UHPC concrete. UHPC has high tensile strength, which can prevent the steel bars from being pulled out and improve the integrity of the bridge pier.

[0023] A construction method for a socket-type bridge pier graded energy dissipation structure using UHPC and ECC layered filling is carried out in the following steps: 1) prefabricating a bridge pier column and a cap with a groove in a factory, wherein longitudinal reinforcement is reserved in the pier column, a grouting corrugated pipe is pre-embedded at the bottom of the pier column, and a plurality of L-shaped steel bars are reserved for the cap; 2) at the construction site, assembling the pier column and the cap, placing the pier column in the center of the groove, inserting the steel bars partially protruding from the cap groove into the grouting corrugated pipe reserved at the bottom of the pier column, so that the longitudinal reinforcement reserved in the pier column and the cap are aligned with each other. Reinforcement overlap is reserved in the cap; 3) Prestressed tendon fixing anchors are set at the bottom of the cap, and prestressed tendon tensioning anchors are set at the top of the pier, and the prestressed tendons are passed through the prestressed tendon holes of the pier column and the cap to tighten the pier column and the cap; 4) UHPC is poured into the grouting corrugated pipe to complete the overlap of the cap steel bars and the pier column longitudinal bars; 5) First, a layer of UHPC is poured in the groove, and then ECC is poured in the gap between the UHPC and the outer wall of the pier column root to form a whole, completing the final connection between the pier column and the cap.

[0024] In this structure, the reserved steel bars in the prefabricated piers and the abutments make the construction more convenient, improve the construction efficiency, and reduce the difficulty of on-site pouring; the reserved grouting bellows in the piers are used to grout the UHPC, which improves the strength, toughness and durability. UHPC has the characteristics of high early strength and fast development speed, so the construction speed is accelerated; at the same time, a layer of UHPC is first poured in the gap between the prefabricated piers and the abutments, and then ECC is filled between the UHPC and the root. Due to its low strength, ECC first produces ductile failure, followed by crack failure in the plastic hinge area at the bottom of the pier, and finally the reserved steel bars at the bottom of the abutment show bending yield. The bridge piers dissipate energy in stages, so they will not be damaged or will be damaged very little in an earthquake, and the size of the prefabricated components does not need to be very precise, which reduces the difficulty of construction.

[0025] As described above, it is only the preferred embodiment of the present invention, and it is not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A socket-type pier hierarchical energy dissipation structure using UHPC and ECC for layered filling, characterized in that: It includes a cap and a prefabricated pier column located on the cap. The upper surface of the cap is provided with a groove, the bottom of the pier column is placed in the groove, a connecting sleeve is reserved inside the pier column, a number of reserved longitudinal reinforcements inside the pier column are overlapped with a number of reserved reinforcements buried in the cap through the connecting sleeve, and the pier column and the cap are tightened by prestressed reinforcements; a layer of UHPC concrete is cast on the inner wall of the groove, and the gap between the UHPC concrete layer and the outer wall of the pier column root is filled with an ECC concrete layer; the prestressed reinforcement is an unbonded prestressed reinforcement; and the connecting sleeve is a grouting corrugated pipe.

2. The socket-type pier hierarchical energy dissipation structure using UHPC and ECC for layered filling according to claim 1, characterized in that: The reserved steel bars inside the pedestal are L-shaped steel bars, which are fixed in the pedestal. The vertical section of the L-shaped steel bars is fixed in the pedestal by pouring concrete in advance, and partially extends outside the groove of the pedestal. The extended part is overlapped with the longitudinal reinforcement of the pier column in the connecting sleeve.

3. The socket pier hierarchical energy dissipation structure using UHPC and ECC for layered filling according to claim 1, characterized in that: The grouting in the connecting sleeve of the pier column is UHPC concrete.

4. A construction method of a socket-type pier hierarchical energy dissipation structure filled with UHPC and ECC in layers as described in any one of claims 1-3, characterized in that, The following steps are followed: 1) Prefabricate bridge piers and caps with grooves in the factory, wherein longitudinal reinforcement is reserved in the piers, grouting corrugated pipes are embedded at the bottom of the piers, and a number of L-shaped steel bars are reserved for the caps; 2) At the construction site, assemble the piers and caps, place the piers in the exact center of the grooves, insert the steel bars partially protruding from the cap grooves into the grouting corrugated pipes reserved at the bottom of the piers, so that the longitudinal reinforcement reserved in the piers and the steel bars reserved in the caps overlap; 3) Set prestressed tendon fixing anchors at the bottom of the caps, set prestressed tendon tensioning anchors at the top of the piers, pass the prestressed tendons through the prestressed tendon channels of the piers and caps, and tighten the piers and caps; 4) Pour UHPC into the grouting corrugated pipes to complete the overlap of the cap steel bars and the pier longitudinal reinforcement; 5) First, cast a layer of UHPC at the grooves, and then cast ECC in the gap between the UHPC and the outer wall of the pier root to form a whole, thus completing the final connection between the piers and caps.

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