Construction methods and bearing capacity calculation methods for hybrid fiber UHPC assembled hollow bridge piers

Abstract

This invention relates to the structure, construction method, and bearing capacity calculation method of hybrid fiber UHPC assembled hollow bridge piers, belonging to the field of prefabricated structure engineering technology. It includes prefabricated hollow pier columns and foundations. By using hybrid fiber UHPC, pre-embedded large-diameter corrugated pipes, and high-strength stainless steel reinforcement in the prefabricated hollow pier columns, the prefabricated hollow bridge piers are connected by grouting and socket joints, ensuring the reliability and seismic safety of the connection structure. The connection between the high-strength stainless steel reinforcement and the pre-embedded large-diameter corrugated pipes in the foundation can resist pull-out forces in the joint area, while the horizontal forces are borne by the UHPC. This connection structure solves the problem of prefabricated bridge pier damage caused by pull-out forces and proposes a method for calculating and designing the bending bearing capacity of the prefabricated hollow pier column section and prefabricated joints, improving the reliability of the connection and the seismic performance of the piers. This invention optimizes the connection method between the prefabricated hollow pier columns and the foundation, improves bridge construction efficiency and seismic performance, and reduces the impact on the surrounding environment.

Description

Technical Field

[0001] This invention relates to the construction, construction method, and bearing capacity calculation method of hybrid fiber UHPC assembled hollow bridge piers, belonging to the field of prefabricated structure engineering technology. Background Technology

[0002] Against the backdrop of the national strategy to build a strong transportation nation, my country is comprehensively promoting the high-quality development of transportation infrastructure, actively driving development in transportation infrastructure construction, technological innovation, and management optimization. Bridges, as a crucial node and key link in transportation infrastructure construction, are experiencing a surge in demand. However, traditional on-site casting methods have significant drawbacks, including long construction cycles, substantial environmental pollution, high construction noise, and difficulty in controlling construction quality. These shortcomings are particularly prominent in the current context of pursuing high-quality development and green construction. Prefabricated construction technology offers an effective solution to these problems. This technology, through the factory prefabrication of components and rapid on-site assembly, can significantly shorten the construction cycle and reduce environmental pollution. Furthermore, it ensures standardized control of components during the production process, effectively guaranteeing the quality of prefabricated components.

[0003] However, many provinces in my country are located in seismically active zones, making the seismic performance of prefabricated bridge structures crucial. Existing prefabricated technologies still face numerous challenges in practical applications in seismically active areas. Due to inadequate design of connection nodes between prefabricated components, stress concentration easily occurs in these node areas under seismic loads, leading to concrete cracking, steel reinforcement yielding, and even overall failure. These problems not only threaten building safety but also increase maintenance costs. Summary of the Invention

[0004] In view of the above-mentioned defects in the existing technology, this invention proposes a hybrid fiber UHPC assembled hollow bridge pier structure, construction method and bearing capacity calculation method to solve the problem of precast bridge pier damage caused by pull-out force. It also proposes a calculation and design method for the bending bearing capacity of precast hollow pier column section and assembled node, which improves the reliability of connection and the seismic performance of bridge pier.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A hybrid fiber UHPC (ultra-high performance concrete) assembled hollow bridge pier structure includes a foundation and a precast hollow pier column inserted into a slot in the upper part of the foundation, and also includes a pre-embedded large-diameter corrugated pipe and UHPC grouting material. A large-diameter corrugated pipe is pre-embedded in the foundation at the bottom of the socket. The large-diameter corrugated pipe consists of multiple sets, which are evenly distributed around the socket. The precast hollow pier is equipped with several high-strength stainless steel bars. The bottom of the high-strength stainless steel bars extends out of the bottom surface of the precast hollow pier and is inserted vertically into the large-diameter corrugated pipe. The socket at the bottom of the precast hollow pier is connected to the interior of the large-diameter corrugated pipe and is filled with UHPC grout.

[0007] Furthermore, the precast hollow pier is a hollow column, and the interior of the precast hollow pier has a hollow area with a hollow ratio of 50% to 70%.

[0008] Furthermore, the precast hollow pier column is also provided with several precast hollow pier column longitudinal bars and several precast hollow pier column stirrups; wherein, the precast hollow pier column stirrups are respectively tied to the high-strength stainless steel bars and the precast hollow pier column longitudinal bars.

[0009] Furthermore, the foundation top is provided with horizontal longitudinal and transverse reinforcement bars, the bearing socket bottom is provided with horizontal longitudinal and transverse reinforcement bars, the foundation bottom is provided with horizontal longitudinal and transverse reinforcement bars, the foundation stirrups are respectively tied to the foundation top horizontal longitudinal and transverse reinforcement bars and the foundation bottom horizontal longitudinal and transverse reinforcement bars, and the bearing socket bottom stirrups are respectively tied to the bearing socket bottom horizontal longitudinal and transverse reinforcement bars and the foundation bottom horizontal longitudinal and transverse reinforcement bars.

[0010] Furthermore, the diameter of the high-strength stainless steel reinforcement is greater than or equal to the diameter of the longitudinal reinforcement of the precast hollow pier column. Furthermore, the UHPC grouting material has a compressive strength of not less than 120 MPa and a tensile strength of not less than 10 MPa.

[0011] Furthermore, a 10-30mm grouting joint is arranged around the connection between the precast hollow pier and the foundation; the insertion depth of the precast hollow pier is greater than 0.6 times the side length of the precast hollow pier.

[0012] Furthermore, a grout layer with a thickness of 10-30mm is provided at the bottom of the socket.

[0013] The construction method for the above-mentioned hybrid fiber UHPC assembled hollow bridge pier structure specifically includes the following steps: S1. In the factory, tie high-strength stainless steel bars, precast hollow pier longitudinal bars, and precast hollow pier stirrups, support the formwork, pour concrete, cure the specimens, remove the formwork, and complete the production of the precast hollow pier. S2. On the construction site, tie the horizontal longitudinal and transverse reinforcement bars at the top of the foundation, the horizontal longitudinal and transverse reinforcement bars at the bottom of the socket, the horizontal longitudinal and transverse reinforcement bars at the bottom of the foundation, the foundation stirrups, and the stirrups at the bottom of the socket. After tying the foundation steel reinforcement frame, reserve the socket, place the pre-embedded large-diameter corrugated pipe, support the formwork, pour concrete, cure the test specimens, remove the formwork, and complete the foundation construction. S3. Transport the precast hollow pier to the construction site, lay a 10-30mm layer of grout on the bottom surface of the foundation socket, insert the high-strength stainless steel bars of the precast hollow pier into the pre-embedded large-diameter corrugated pipe of the foundation through the socket assembly method, adjust the horizontality and verticality of the precast hollow pier, and complete the placement of the precast hollow pier. S4. Mix the mixed fiber UHPC on site and fill the gap between the precast hollow pier and the foundation bearing slot with UHPC grout. Let the UHPC grout flow into the large-diameter corrugated pipe until the UHPC grout is flush with the top surface of the foundation, so that the precast hollow pier and the foundation are connected as a whole, and the assembly of the precast hollow pier and the foundation is completed.

[0014] The above-mentioned method for calculating the flexural bearing capacity of the hybrid fiber UHPC assembled hollow pier structure includes: axial force and bending moment at the bottom of the precast hollow pier column, bending moment generated by load at the joint of the assembled hollow pier, and bending moment generated by the joint load on the center of the precast hollow pier section. (a) Axial force and bending moment at the bottom of precast hollow piers: The precast hollow pier-foundation socket joint is analyzed. For the bottom section of the precast hollow pier, the bending moment bearing capacity under the combined action of horizontal force and axial force is calculated using the strain compatibility method. The calculation formulas for axial force and bending moment at the bottom section of the precast hollow pier are as follows: Formula for calculating axial force N in precast hollow pier section:

[0015] Formula for calculating the bending moment of precast hollow pier sections:

[0016] in: The resultant force of the concrete stress block in the compression zone; The resultant force of the compressive steel bars; The resultant force of the tensile reinforcement; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; and These are the distances from the edge of the concrete on the compression side of the precast hollow pier section to the center of the compression reinforcement and the tension reinforcement, respectively. The side length of the precast hollow pier section; This is the depth coefficient of the rectangular block; (ii) Bending moment generated by loads at the joints of assembled hollow piers and bending moment generated by nodal loads on the center of the precast hollow pier section. The analysis of the precast hollow pier-foundation socket joint reveals the following formula for calculating the bending moment generated by the joint load at the center of the precast hollow pier section: In the bending moment model, the vertical friction force on the compression side of the pier column... Vertical friction force on the tension side of the pier column Each is determined by the horizontal bearing capacity of the compression side. and tension side horizontal bearing capacity Provides horizontal friction force on the bottom surface of the pier column. Vertical bearing capacity from the bottom of the pier supply:

[0017]

[0018] in: This is the distance between the top of the stress block and the neutral axis. This is the distance between the bottom of the stress block and the neutral axis. The effective width of the stress block. Take the side length of the precast hollow pier column perpendicular to the direction of the horizontal load; This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the top. This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the bottom. Horizontal load:

[0019] Axial bearing capacity at the end:

[0020] in, For axial loads; For the vertical friction force on the compression side of the pier column, For the vertical friction force on the tension side of the pier column, The horizontal friction force on the bottom surface of the pier column; For pulling force; The coefficient of friction between different concrete materials; The bending moment generated by the nodal load on the center of the precast hollow pier section:

[0021] in, This is the distance from the horizontal loading point to the top surface of the foundation. The depth of the precast hollow pier column; and They are respectively and The horizontal distance to the center of the precast hollow pier is always taken as half the size of the precast hollow pier. End bearing capacity Horizontal distance to the center ; The thickness of the protective layer for precast hollow piers; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; The bending moment in the nodal region satisfies: .

[0022] By adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art: First, this invention effectively disperses seismic energy and delays crack propagation through optimized connection structure design. Second, this invention also establishes a precise design method for the flexural bearing capacity of sections and nodes, ensuring the flexural mechanical performance of the structure, enhancing its seismic safety and reliability, and reducing safety hazards.

[0023] This invention addresses the shortcomings of existing prefabricated bridge connection technologies in terms of seismic performance, durability, and ease of construction. It innovatively proposes a novel prefabricated bridge connection structure based on UHPC (Ultra-High-Potential Carbon). UHPC possesses excellent durability and impermeability, significantly improving the stability of prefabricated hollow bridge piers and effectively resisting chloride ion corrosion. This invention is suitable for harsh environments such as nearshore high-salt-spray environments, urban road high-load, high-frequency environments, and seismically active areas. It can significantly extend the service life of prefabricated bridges, reduce the total life-cycle maintenance cost, and provide important technical support for the high-quality and green development of transportation infrastructure. Details are as follows: 1. Due to various uncertainties such as weather and environment, the quality of traditional cast-in-place piers is difficult to guarantee. Therefore, this invention adopts advanced technology of standardized prefabricated hollow pier processing in a factory. By centrally prefabricating hollow piers in a specialized factory, the quality of each prefabricated hollow pier can be ensured. Furthermore, the application of high-strength stainless steel reinforcement further enhances the structural stability of the prefabricated components, improving the overall reliability and durability of the structure.

[0024] 2. Compared with traditional bridge construction techniques, prefabricated construction methods can significantly reduce on-site operations, improve construction efficiency, and shorten the construction cycle while ensuring construction quality and component precision. Simultaneously, by reducing on-site concrete mixing and vibration processes, it can significantly reduce noise, dust, and waste emissions during construction, effectively minimizing pollution to the surrounding environment and aligning with modern green construction principles. Furthermore, the corrugated pipe connection method used in this invention effectively reduces the component insertion depth, facilitating the transportation, hoisting, and installation of prefabricated components, further enhancing construction convenience, indirectly shortening the construction cycle, and reducing construction costs.

[0025] 3. This invention utilizes hybrid fiber UHPC material, which possesses excellent impermeability and durability. Its impermeability effectively prevents the penetration of corrosive media such as moisture and chloride ions, while its durability ensures the structure's service life. Furthermore, the use of high-strength stainless steel reinforcement not only further enhances the overall strength of the structure but also significantly improves the reliability and durability of the connections. This ensures the bridge piers can operate stably and sustainably in extreme environments such as frigid conditions, reducing frequent construction work required for structural repairs. Consequently, it significantly lowers the operational costs of inspection, maintenance, and upkeep throughout the entire lifecycle, providing a solid guarantee for bridge engineering.

[0026] 4. This invention relates to a hybrid fiber UHPC prefabricated hollow bridge pier connection structure and a method for calculating flexural bearing capacity. The flexural bearing capacity calculation method accurately calculates the flexural bearing capacity, preventing pier cracking or deformation due to insufficient bearing capacity during construction, while ensuring flexural mechanical properties, reducing the degree of earthquake damage to the pier, and minimizing safety hazards. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the elevation of the invention; Figure 2 This is the present invention. Figure 1 A schematic diagram of the AA cross-section; Figure 3 This is the present invention. Figure 1 BB cross-sectional diagram; Figure 4 This is a schematic diagram of the prefabricated hollow pier column processing of the present invention, wherein (a) is a schematic diagram of the reinforcing steel of the prefabricated hollow pier column and (b) is an overall schematic diagram of the prefabricated hollow pier column; Figure 5 This is a schematic diagram of the basic processing of the present invention, wherein (a) is a schematic diagram of the basic reinforcement and (b) is a schematic diagram of the overall foundation; Figure 6This is a schematic diagram of the prefabricated assembly process of the prefabricated hollow pier column-foundation of the present invention; wherein (a) is an overall schematic diagram of the prefabricated hollow pier column, (b) is an overall schematic diagram of the foundation, (c) is an assembly diagram of the prefabricated hollow bridge pier, (d) is a schematic diagram of the UHPC filling slot and large-diameter corrugated pipe, and (e) is an overall schematic diagram of the assembly of the prefabricated hollow pier column-foundation. Figure 7 This is the bending moment analysis diagram of the precast hollow reinforced concrete pier section of the present invention. Figure 8 This is the bending moment analysis diagram of the precast hollow pier-foundation socket joint of the present invention. Detailed Implementation The following is in conjunction with the appendix Figure 1-8 The present invention will be further described in detail below to facilitate a clear understanding of the invention, but these descriptions do not constitute a limitation thereof.

[0028] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] Example 1 As attached Figure 1-5 As shown, this embodiment of a hybrid fiber UHPC (ultra-high performance concrete) assembled hollow bridge pier structure includes a foundation 2 and a precast hollow pier column 1 inserted into a socket 3 on the upper part of the foundation 2, and also includes a pre-embedded large-diameter corrugated pipe 4 and UHPC grouting material 13; in this embodiment, the precast hollow pier column 1 is a hollow column, and the precast hollow pier column 1 has a precast hollow pier column hollow area 14 inside, with a hollowness of 60%.

[0031] like Figure 1-2 and Figure 4As shown, the precast hollow pier 1 also contains several precast hollow pier longitudinal bars 6 and several precast hollow pier stirrups 7; wherein, the precast hollow pier stirrups 7 are respectively tied to the high-strength stainless steel bars 5 and the precast hollow pier longitudinal bars 6. The precast hollow pier 1 contains several high-strength stainless steel bars 5, the bottom of the high-strength stainless steel bars 5 extends out of the bottom surface of the precast hollow pier 1 and is correspondingly inserted vertically into the large-diameter corrugated pipe 4; at the same time, in this embodiment, the diameter of the high-strength stainless steel bars 5 is greater than or equal to the diameter of the precast hollow pier longitudinal bars 6; like Figure 1-3 as well as Figure 5 As shown, the top of foundation 2 is provided with horizontal longitudinal and transverse staggered reinforcement bars 8, the bottom of foundation 3 is provided with horizontal longitudinal and transverse staggered reinforcement bars 9, the bottom of foundation 2 is provided with horizontal longitudinal and transverse staggered reinforcement bars 10, the foundation stirrups 11 are tied to the top of foundation horizontal longitudinal and transverse staggered reinforcement bars 8 and the bottom of foundation horizontal longitudinal and transverse staggered reinforcement bars 10 respectively, and the bottom of foundation stirrups 12 are tied to the bottom of foundation horizontal longitudinal and transverse staggered reinforcement bars 9 and the bottom of foundation horizontal longitudinal and transverse staggered reinforcement bars 10 respectively.

[0032] like Figure 1 , Figure 3 as well as Figure 5 As shown, a large-diameter corrugated pipe 4 is pre-embedded in the foundation 2 at the bottom of the socket 3. Multiple sets of large-diameter corrugated pipes 4 are evenly distributed around the socket 3. The socket 3 at the bottom of the precast hollow pier 1 is connected to the interior of the large-diameter corrugated pipe 4 and is filled with UHPC grout 13. In this embodiment, the compressive strength of the UHPC grout 13 is not less than 120 MPa, and the tensile strength is not less than 10 MPa. Furthermore, a 20 mm thick bedding grout layer is provided at the bottom of the socket 3.

[0033] In this embodiment, a 20mm grouting joint is arranged around the connection between the precast hollow pier 1 and the foundation 2; the insertion depth of the precast hollow pier 1 is 0.8 times the side length of the precast hollow pier 1.

[0034] Example 2 like Figure 6 The diagram illustrates the construction method for the hybrid fiber UHPC assembled hollow bridge pier structure described in Example 1, specifically including the following steps: S1. Bind high-strength stainless steel bars 5, precast hollow pier longitudinal bars 6, and precast hollow pier stirrups 7 in the factory, support the formwork, pour concrete, cure the specimens, remove the formwork, and complete the production of precast hollow pier 1. S2. On the construction site, tie the horizontal longitudinal reinforcement 8 at the top of the foundation 2, the horizontal longitudinal reinforcement 9 at the bottom of the socket, the horizontal longitudinal reinforcement 10 at the bottom of the foundation, the foundation stirrups 11, and the socket stirrups 12. After tying the foundation steel reinforcement frame, reserve the socket 3, place the pre-embedded large-diameter corrugated pipe 4, support the formwork, pour concrete, cure the test specimens, remove the formwork, and complete the construction of foundation 2. S3. Transport the precast hollow pier 1 to the construction site, lay a 20mm layer of grout on the bottom surface of the foundation socket 3, insert the high-strength stainless steel reinforcement 5 of the precast hollow pier into the pre-embedded large-diameter corrugated pipe 4 of the foundation through the socket assembly method, adjust the horizontality and verticality of the precast hollow pier 1, and complete the placement of the precast hollow pier. S4. Mix the mixed fiber UHPC on site and fill the gap between the precast hollow pier 1 and the foundation bearing slot 3 with UHPC grout 13. Let the UHPC grout 13 flow into the large diameter corrugated pipe 4 until the UHPC grout 13 is flush with the top surface of the foundation 2, so that the precast hollow pier 1 and the foundation 2 are connected into a whole, and the assembly of the precast hollow pier 1 and the foundation 2 is completed.

[0035] Example 3 like Figure 7-8 The diagram illustrates the method for calculating the flexural bearing capacity of the hybrid fiber UHPC assembled hollow bridge pier structure described in Example 1, including... Figure 7 The axial force and bending moment at the bottom of the precast hollow pier column shown are as follows Figure 8 The bending moment generated by the load at the joint of the assembled hollow pier and the bending moment generated by the joint load on the center of the precast hollow pier section are shown. (a) Axial force and bending moment at the bottom of precast hollow piers: An analysis of the precast hollow pier-foundation socket joint is conducted. For the bottom section of the precast hollow pier, the bending moment bearing capacity under the combined action of horizontal and axial forces is calculated using the strain compatibility method. The bending moment analysis diagram of the precast hollow pier section is shown below. Figure 7 As shown. The formulas for calculating the axial force and bending moment at the bottom section of the precast hollow pier are as follows: Formula for calculating axial force N at section 1 of precast hollow pier:

[0036] Formula for calculating the bending moment of section 1 of precast hollow pier:

[0037] in: The resultant force of the concrete stress block in the compression zone; The resultant force of the compressive steel bars; The resultant force of the tensile reinforcement; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; and These are the distances from the edge of the concrete on the compression side of the precast hollow pier section to the center of the compression reinforcement and the tension reinforcement, respectively. The side length of the precast hollow pier section; This is the depth coefficient of the rectangular block; Verification of the calculation formula: The axial force formula follows the basic principle of vertical force balance in reinforced concrete compression-bending members. The summation term is adapted to the actual reinforcement situation of multiple steel bars. The superposition and cancellation relationship between the resultant force of concrete and the resultant force of steel bars in the compression zone is completely consistent with the actual stress state of the bottom section of the precast hollow pier column, and there is no conflict with the calculation premise of the strain coordination method.

[0038] The bending moment formula takes the center of the cross section as the origin of the moment and calculates it by superimposing the moments of each force unit. All lever arm parameters are precisely matched with the cross section dimensions, and the direction of the moment is consistent with the rotational trend of the actual force. It strictly satisfies the moment balance condition around the center of the cross section and is suitable for the bending force characteristics of precast hollow piers with rectangular cross sections.

[0039] (ii) Bending moment generated by loads at the joints of assembled hollow piers and bending moment generated by nodal loads on the center of the precast hollow pier section. An analysis of the precast hollow pier-foundation socket joint is conducted. The calculation model for the bending moment bearing capacity of the precast hollow pier-foundation socket joint connection under compression and bending is as follows: Figure 8 As shown. The formula for calculating the bending moment generated by the nodal load at the center of the precast hollow pier section is as follows: In the bending moment model, the vertical friction force on the compression side of the pier column... Vertical friction force on the tension side of the pier column Each is determined by the horizontal bearing capacity of the compression side. and tension side horizontal bearing capacity Provides horizontal friction force on the bottom surface of the pier column. Vertical bearing capacity from the bottom of the pier supply:

[0040]

[0041] in: This is the distance between the top of the stress block and the neutral axis. This is the distance between the bottom of the stress block and the neutral axis. The effective width of the stress block. Take the side length of the precast hollow pier column perpendicular to the direction of the horizontal load; This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the top. This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the bottom. Horizontal load:

[0042] Axial bearing capacity at the end:

[0043] in, For axial loads; For the longitudinal friction force on the compression side of the pier column, For the longitudinal friction force on the tension side of the pier column, The horizontal friction force on the bottom surface of the pier column; For pulling force; The coefficient of friction between different concrete materials; The bending moment generated by the nodal load on the center of the precast hollow pier section:

[0044] in, This is the distance from the horizontal loading point to the top surface of the foundation. The depth of the precast hollow pier column; and They are respectively and The horizontal distance to the center of the precast hollow pier is always taken as half the size of the precast hollow pier. End bearing capacity Horizontal distance to the center ; The thickness of the protective layer for precast hollow piers; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; The bending moment in the nodal region satisfies: .

[0045] Verification of the calculation formula: The formula for horizontal bearing capacity adopts the resultant force calculation form of triangular stress distribution, which matches the actual compressive stress distribution of the concrete of the pier cap in the node area. The effective width of the stress block is taken as the side length of the precast hollow pier column, which fits the actual force-bearing width of the node socket contact, and conforms to the calculation principle of the resultant force of contact compressive stress.

[0046] The formulas for horizontal load and axial bearing capacity follow the force balance conditions in the horizontal and vertical directions, respectively, accurately reflecting the force transmission and superposition relationship under the compression-bending coupling effect of the node, and are suitable for the force mechanism of the socket joint.

[0047] The nodal bending moment formula satisfies The basic moment relationships are calculated, and refined calculations are achieved through the superposition of spatial moments of each force unit. All lever arm parameters are highly consistent with the node structure and the actual position of the force unit, satisfying the spatial moment equilibrium condition; nodal bending moment constraints. It conforms to the seismic design principle of strong nodes and weak components, and sets a safety factor of 1.25 to ensure that the nodes fail before the piers, thus possessing both engineering rationality and seismic safety.

[0048] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the structure of the present invention. The arrangement and quantity of the present invention are not limited to this example and can be optimized according to actual engineering conditions. Any modifications, equivalent changes, and decorations made to the above embodiments based on the technical principles of the present invention, without departing from the scope of the present invention, are still within the scope of the present invention.

Claims

1. A hybrid fiber UHPC assembled hollow bridge pier structure, comprising a foundation (2) and a precast hollow pier column (1) inserted into a socket (3) on the upper part of the foundation (2), characterized in that: It also includes pre-embedded large-diameter corrugated pipes (4) and UHPC grouting material (13); A large-diameter corrugated pipe (4) is pre-embedded in the foundation (2) at the bottom of the socket (3). The large-diameter corrugated pipe (4) consists of multiple sets and is evenly distributed around the socket (3). The prefabricated hollow pier (1) is provided with several high-strength stainless steel bars (5). The bottom of the high-strength stainless steel bars (5) extends out of the bottom surface of the prefabricated hollow pier (1) and is inserted vertically into the interior of the large-diameter corrugated pipe (4). The socket (3) at the bottom of the precast hollow pier (1) is connected to the interior of the large-diameter corrugated pipe (4) and is filled with UHPC grout (13).

2. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The precast hollow pier (1) is a hollow column, and the precast hollow pier (1) has a hollow area (14) inside, with a hollow ratio of 50% to 70%.

3. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The precast hollow pier (1) is also provided with several precast hollow pier longitudinal bars (6) and several precast hollow pier stirrups (7); wherein the precast hollow pier stirrups (7) are respectively tied to the high-strength stainless steel bars (5) and the precast hollow pier longitudinal bars (6).

4. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The foundation (2) is provided with horizontal longitudinal reinforcement (8) at the top, and horizontal longitudinal reinforcement (9) at the bottom of the socket (3). The foundation (2) is provided with horizontal longitudinal reinforcement (10) at the bottom. The foundation stirrups (11) are tied to the horizontal longitudinal reinforcement (8) at the top and the horizontal longitudinal reinforcement (10) at the bottom. The socket stirrups (12) are tied to the horizontal longitudinal reinforcement (9) at the bottom and the horizontal longitudinal reinforcement (10) at the bottom.

5. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The diameter of the high-strength stainless steel bar (5) is greater than or equal to the diameter of the longitudinal bar (6) of the precast hollow pier column.

6. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The compressive strength of the UHPC grout (13) is not less than 120 MPa and the tensile strength is not less than 10 MPa.

7. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: A 10-30mm grouting joint is arranged around the connection between the precast hollow pier (1) and the foundation (2); the insertion depth of the precast hollow pier (1) is greater than 0.6 times the side length of the precast hollow pier (1).

8. The hybrid fiber UHPC assembled hollow bridge pier structure according to claim 1, characterized in that: The bottom of the socket (3) is provided with a grout layer with a thickness of 10-30mm.

9. A construction method for a hybrid fiber UHPC assembled hollow bridge pier structure according to any one of claims 1-8, characterized in that, Specifically, the steps include the following: S1. Tie high-strength stainless steel bars (5), precast hollow pier longitudinal bars (6), and precast hollow pier stirrups (7) in the factory, support the formwork, pour concrete, cure the specimens, remove the formwork, and complete the production of precast hollow pier (1). S2. Tie the horizontal longitudinal reinforcement (8) at the top of the foundation (2), the horizontal longitudinal reinforcement (9) at the bottom of the socket (10), the horizontal longitudinal reinforcement (11), and the bottom of the socket (12) at the construction site. After tying the foundation steel reinforcement frame, reserve the socket (3), place the pre-embedded large-diameter corrugated pipe (4), support the formwork, pour concrete, cure the specimen, remove the formwork, and complete the construction of the foundation (2). S3. Transport the precast hollow pier (1) to the construction site, lay a 10-30mm grout layer on the bottom surface of the foundation socket (3), insert the high-strength stainless steel bar (5) of the precast hollow pier into the pre-embedded large-diameter corrugated pipe (4) of the foundation through the socket assembly method, adjust the horizontality and verticality of the precast hollow pier (1), and complete the placement of the precast hollow pier. S4. Mix the mixed fiber UHPC on site and fill the gap between the precast hollow pier (1) and the foundation socket (3) with UHPC grout (13). Let the UHPC grout (13) flow into the large diameter corrugated pipe (4) until the UHPC grout (13) is flush with the top surface of the foundation (2). This will connect the precast hollow pier (1) and the foundation (2) into a whole and complete the assembly of the precast hollow pier (1) and the foundation (2).

10. A method for calculating the flexural bearing capacity of a hybrid fiber UHPC assembled hollow bridge pier structure according to any one of claims 1-8, characterized in that, include: Axial force and bending moment at the bottom of precast hollow pier column, bending moment generated by load at the joint of assembled hollow pier, and bending moment generated by joint load on the center of the precast hollow pier column section; (a) Axial force and bending moment at the bottom of precast hollow piers: The precast hollow pier-foundation socket joint is analyzed. For the bottom section of the precast hollow pier, the bending moment bearing capacity under the combined action of horizontal force and axial force is calculated using the strain compatibility method. The calculation formulas for axial force and bending moment at the bottom section of the precast hollow pier are as follows: Formula for calculating axial force N at section (1) of precast hollow pier: Formula for calculating the bending moment of the section of precast hollow pier (1): in: The resultant force of the concrete stress block in the compression zone; The resultant force of the compressive steel bars; The resultant force of the tensile reinforcement; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; and These are the distances from the edge of the concrete on the compression side of the precast hollow pier section to the center of the compression reinforcement and the tension reinforcement, respectively. The side length of the precast hollow pier section; This is the depth coefficient of the rectangular block; (ii) Bending moment generated by loads at the joints of assembled hollow piers and bending moment generated by nodal loads on the center of the precast hollow pier section. The analysis of the precast hollow pier-foundation socket joint reveals the following formula for calculating the bending moment generated by the joint load at the center of the precast hollow pier section: In the bending moment model, the vertical friction force on the compression side of the pier column... Vertical friction force on the tension side of the pier column Each is determined by the horizontal bearing capacity of the compression side. and tension side horizontal bearing capacity Provides horizontal friction force on the bottom surface of the pier column. Vertical bearing capacity from the bottom of the pier supply: in: This is the distance between the top of the stress block and the neutral axis. This is the distance between the bottom of the stress block and the neutral axis. The effective width of the stress block. Take the side length of the precast hollow pier column perpendicular to the direction of the horizontal load; This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the top. This refers to the compressive stress in the concrete of the foundation cap at the stress distribution point at the bottom. Horizontal load: Axial bearing capacity at the end: in, For axial loads; For the vertical friction force on the compression side of the pier column, Vertical friction force on the tension side of the pier column and The horizontal friction force on the bottom surface of the pier column; For pulling force; The coefficient of friction between different concrete materials; The bending moment generated by the nodal load on the center of the precast hollow pier section: in, This is the distance from the horizontal loading point to the top surface of the foundation. The depth of the precast hollow pier column; and They are respectively and The horizontal distance to the center of the precast hollow pier is always taken as half the size of the precast hollow pier. End bearing capacity Horizontal distance to the center ； The thickness of the protective layer for precast hollow piers; This refers to the height of the concrete compression zone at the bottom section of the precast hollow pier column; The bending moment in the nodal region satisfies: 。

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