Mixing high-strength spiral stirrup reinforced UHPC centrifugal tube-NC combined pier column structure

Abstract

A mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC combined pier column structure is composed of a UHPC centrifugal tube (3) and an NC combined pier column (4). The UHPC centrifugal tube is formed by centrifugally pouring a first layer of steel reinforcement framework and ultra-high performance concrete; the NC combined pier column is formed by pouring common concrete by combining a second-layer steel reinforcement framework with a UHPC centrifugal tube outer mold; the second layer of steel reinforcement framework is arranged in the UHPC centrifugal tube, and the UHPC centrifugal tube and the NC combined pier column form a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC combined pier column structure. According to the bridge pier column, the centrifugal forming technology is combined, the mixed high-strength spiral stirrups are configured, on the basis that UHPC and NC interface deformation coordination is achieved, lateral constraint provided by the UHPC prefabricated pipe for the internal NC is enhanced through the high-strength spiral steel bars, the ultrahigh fracture toughness of UHPC materials is enhanced, and the anti-seismic performance of the bridge pier column is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of bridge construction, and particularly relates to a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC combined pier column structure. Background Art

[0002] At present, normal concrete (NC) has become the most widely used cement-based material in civil engineering due to its good performance, simple construction process and relatively low cost. However, it does not have an advantage in the field of structural seismic resistance due to the constraints of material durability, damage tolerance and energy dissipation capacity. The destruction of reinforced concrete piers under earthquakes occurs from time to time. Therefore, it is an important practical need to explore a pier structure with good durability and seismic energy dissipation capacity.

[0003] In recent years, some scholars have tried to use ultra-high performance concrete (UHPC) instead of NC for bridge piers and conducted research on its seismic performance. It is worth noting that although a series of results have been achieved in the research on the use of UHPC for structural seismic resistance at home and abroad, most of the current research applies UHPC to the overall structure. Considering that the cost of UHPC is relatively expensive at this stage, the use of all-UHPC structure is not conducive to its engineering promotion and application. For this reason, many composite pier structures based on UHPC materials, such as outer tube UHPC mold column-inner core reinforced concrete composite bridge piers, active powder concrete prefabricated pipe composite columns, and UHPC external reinforced concrete bridge piers, have been proposed one after another. Through the study of their seismic performance, researchers have shown that based on reasonable performance design, UHPC and NC composite piers not only have good economy, but also can give full play to the advantages of their respective materials and achieve good seismic expectations. However, the existing research also has the following problems:

[0004] (1) The external UHPC thin layer in the composite bridge pier is generally not equipped with steel bars or the steel bars are insufficient in strength, resulting in the superior mechanical properties of the UHPC material not being fully utilized.

[0005] (2) Considering the obvious interface effect of the combination of UHPC and ordinary concrete, there is little targeted research on how to ensure that the two have good interface deformation coordination performance under complex stress conditions (such as earthquake effects). Summary of the invention

[0006] The technical problem to be solved by the utility model is to propose a hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure in order to solve the problems existing in the durability and seismic energy dissipation capacity of the above-mentioned existing composite bridge piers.

[0007] The technical solution for realizing the utility model is as follows: a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure, which is composed of UHPC centrifugal tubes and NC composite pier columns.

[0008] The UHPC centrifugal tube is formed by centrifugally pouring a first layer of steel skeleton and ultra-high performance concrete; the NC composite pier is formed by pouring a second layer of steel skeleton with ordinary concrete; the second layer of steel skeleton is placed in the UHPC centrifugal tube, and the UHPC centrifugal tube and the NC composite pier constitute a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier structure.

[0009] The first layer of steel bar skeleton is formed by staggered arrangement of circular high-strength spiral stirrups and square high-strength spiral stirrups, which are tied together with the first longitudinal steel bars.

[0010] The second layer of steel bar skeleton is formed by binding the first longitudinal steel bars, square high-strength spiral stirrups and the second longitudinal steel bars.

[0011] The second longitudinal steel bar is placed in the middle of the partially exposed square high-strength stirrup in the centrifugal tube, and is connected to both ends of the entire square high-strength spiral stirrup by tying or welding in 1-2 layers.

[0012] The UHPC centrifugal tube has a suitable tube wall thickness selected according to the size of the combined pier structure required for the actual project.

[0013] The circular high-strength spiral stirrups and the square high-strength spiral stirrups have the same rotation direction and are arranged in a staggered manner. The first longitudinal steel bars and the second longitudinal steel bars are the same in number, and 4 to 6 are arranged according to the diameter of the centrifuge tube.

[0014] The beneficial effects of the utility model are:

[0015] (1) Achieve coordinated deformation of the interface between UHPC and NC. The circular high-strength spiral stirrups and the square high-strength spiral stirrups of the utility model are tied with the longitudinal steel bar 1, so that the UHPC centrifugal tube is closely combined with the post-cast NC, effectively improving the overall force performance of the pier column. At the same time, the spirally tied square high-strength spiral stirrups are tied with the longitudinal steel bar 2 to form the steel skeleton of the core concrete column. The partially exposed square stirrups pass through the core concrete column layer by layer, which enhances the restraining effect on the lateral deformation of the core concrete column.

[0016] (2) Fully utilize the fracture toughness of UHCP. In existing composite bridge piers, the external UHPC thin layer is generally not equipped with steel bars or the strength of the steel bars is insufficient, resulting in the superior mechanical properties of UHPC materials not being fully utilized. The utility model uses a hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure to fully utilize the ultra-high fracture toughness of UHPC materials, improve the ductility of concrete pier columns, and enhance the seismic performance of pier columns. At the same time, the lateral constraints provided by the high-strength stirrup reinforced UHPC centrifugal tube to the internal NC are comprehensively considered to further improve the ductility and enhance the bearing capacity of the pier column.

[0017] (3) Achieve a balance between economy and applicability. The utility model adopts the combination of UHPC and NC to solve the problem that the full UHPC structure is expensive and not conducive to engineering promotion and application. While reducing the cost, the utility model uses the circular high-strength spiral stirrups arranged in the center of the UHPC centrifugal tube to fully utilize the superior performance of UHPC. Achieve a balance between economy and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the elevation view of the utility model of hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube;

[0019] Figure 2 This is the elevation view of the utility model of a hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier;

[0020] Figure 3 This is the AA cross-sectional view of the hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column of the utility model;

[0021] Figure 4 It is a schematic diagram of the layout of the first layer of steel bar skeleton of the utility model;

[0022] Figure 5 It is a schematic diagram of the layout of the second layer of steel reinforcement skeleton of the utility model;

[0023] In the figure, 101 is the first longitudinal steel bar; 102 is the second longitudinal steel bar; 201 is the circular high-strength spiral stirrup; 202 is the square high-strength spiral stirrup; 3 is the UHPC centrifugal tube; 4 is the NC composite pier column. DETAILED DESCRIPTION

[0024] This embodiment is a hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure. Figure 2 shown.

[0025] The present embodiment provides a hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure, which is composed of a UHPC centrifugal tube 3 and a NC composite pier column 4.

[0026] The UHPC centrifugal tube is formed by centrifugally pouring a first layer of steel skeleton and ultra-high performance concrete; the NC composite pier is formed by pouring a second layer of steel skeleton with ordinary concrete; the second layer of steel skeleton is placed in the UHPC centrifugal tube, and the UHPC centrifugal tube and the NC composite pier constitute a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier structure.

[0027] In this embodiment, the UHPC centrifugal tube 3 is connected to form a first layer of steel skeleton by circular high-strength spiral hoops 201, square high-strength spiral hoops 202 and the first longitudinal steel bar 101; centrifugal forming technology is used to form a prefabricated tube reinforced with circular high-strength spiral hoops and partially exposed square high-strength hoops in the tube; the square corners of the square high-strength hoops are cast in the middle of the prefabricated tube contour, and the middle of the straight part of the square high-strength hoops is exposed outside the prefabricated tube contour. The second longitudinal steel bar 102 is arranged in the center of the UHPC tube after centrifugal forming, and combined with the square high-strength hoops 202 and the first longitudinal steel bar 101 exposed inside and outside the centrifugal tube to form a second layer of steel skeleton connecting the UHPC centrifugal tube 3 and the post-cast NC. Then, NC is cast in the UHPC centrifugal tube 3 to form a mixed high-strength spiral hoops reinforced UHPC centrifugal tube-NC composite pier column structure.

[0028] The ultra-high performance concrete (UHPC) used in this embodiment has a compressive strength of 116 MPa, a tensile strength of 7.7 MPa, and a steel fiber content of 2%. Ordinary concrete uses C40 concrete commonly used in bridge piers; the first longitudinal steel bar 101 and the mixed high-strength spiral stirrup 2 both use HRB500 threaded steel bars with a diameter of 10 mm, and the second longitudinal steel bar 102 uses HRB400 threaded steel bars with a diameter of 6 mm.

[0029] In this embodiment, the UHPC centrifugal tube 3 is composed of 4 first longitudinal steel bars 101 with a length of 1500mm and circular high-strength spiral stirrups 201 and square high-strength spiral stirrups 202 of equal height and centrally staggered arrangement, forming a cage to form a first layer of steel skeleton, with a stirrup spacing of 80mm. The UHPC centrifugal tube 3 is cast in a centrifugal forming machine using centrifugal forming technology, with a thickness of 50mm. In this embodiment, the four first longitudinal steel bars 101 are arranged in a square with a side length of 282mm; the inner diameter of the circular high-strength spiral stirrup 201 is 400mm; and the square high-strength spiral stirrup 202 has a side length of 282mm. The inner diameter of the cross section of the UHPC centrifugal tube is 350mm and the outer diameter is 450mm.

[0030] The height of the post-cast NC pier in this embodiment is 1500 mm and the diameter is 350 mm. The second longitudinal reinforcement 102 in the NC pier column is made of 4 HRB400 threaded reinforcements, which together with the square high-strength spiral stirrups 202 and the first longitudinal reinforcement 101 form a second layer of reinforcement skeleton.

[0031] In this embodiment, the circular high-strength spiral stirrups 201 and the square high-strength spiral stirrups 202 are both right-handed.

[0032] The construction method of a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure in this embodiment is as follows:

[0033] (1) Fabrication of the first layer of steel skeleton. First, the circular high-strength spiral stirrups 201 are wrapped around four first longitudinal steel bars 101 to form a steel cage for reinforcing the UHPC centrifugal tube 3. Then, square high-strength spiral stirrups 202 are used to wrap around the first longitudinal steel bars 101 in the same direction of rotation in the middle of the circular spiral stirrups 201 to form the first layer of steel skeleton.

[0034] (2) Forming of UHPC centrifugal tubes. Place the first layer of steel bar skeleton in a supporting wheel centrifugal forming machine. Cast UHPC and use the rotating centrifugal force to compact and form a prefabricated tube with circular high-strength spiral stirrups and partially exposed square high-strength stirrups inside the tube. After demolding, steam cure at 90°C for 48 hours and cool to room temperature.

[0035] (3) Production of the second layer of steel skeleton. After the UHPC centrifugal tube 3 is formed, it is cut and trimmed to 1500mm, erected, and four second longitudinal steel bars 102 are placed at the midpoint of the inner side of each square high-strength spiral stirrup 202, and the first layer at both ends of the entire square high-strength spiral stirrup 202 is connected by welding to form a second layer of steel skeleton composed of the first longitudinal steel bar 101, the second longitudinal steel bar 102 and the square high-strength spiral stirrup 202. In this way, the deformation coordination of the interface between UHPC and the post-cast NC is achieved.

[0036] (4) Combination pier column forming. After the second layer of steel skeleton in the UHPC centrifugal tube 3 is completed, ordinary concrete is poured in the tube, and steam-cured at 90°C for 48 hours and cooled to room temperature to form the hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC combination pier column structure of the present invention.

Claims

1. A hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure, characterized in that: The structure consists of a UHPC centrifugal tube and an NC composite pier column; the UHPC centrifugal tube is formed by centrifugally pouring a first layer of steel skeleton and ultra-high performance concrete; the NC composite pier column is formed by pouring ordinary concrete in combination with a second layer of steel skeleton and an outer mold of the UHPC centrifugal tube; the second layer of steel skeleton is placed in the UHPC centrifugal tube, and the UHPC centrifugal tube and the NC composite pier column constitute a mixed high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure.

2. A hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure according to claim 1, characterized in that: The first layer of steel bar skeleton is formed by staggered arrangement of circular high-strength spiral stirrups and square high-strength spiral stirrups, which are tied together with the first longitudinal steel bars.

3. The hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure according to claim 1, characterized in that: The second layer of steel bar skeleton is formed by binding the first longitudinal steel bars, square high-strength spiral stirrups and the second longitudinal steel bars.

4. A hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure according to claim 3, characterized in that: The second longitudinal steel bar is placed in the middle of the partially exposed square high-strength stirrup in the centrifugal tube, and is connected to both ends of the entire square high-strength spiral stirrup by tying or welding in 1-2 layers.

5. The hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure according to claim 2, characterized in that: The circular high-strength spiral stirrups and the square high-strength spiral stirrups have the same rotation direction and are staggered and centrally arranged.

6. The hybrid high-strength spiral stirrup reinforced UHPC centrifugal tube-NC composite pier column structure according to claim 2, characterized in that: The first longitudinal steel bars and the second longitudinal steel bars are the same in number, and 4 to 6 of them are arranged according to the diameter of the centrifuge tube.

Images