Method for controlling longitudinal displacement of top of pier of simply supported girder bridge

Abstract

The invention discloses a method for controlling longitudinal displacement of the top of a pier of a simply supported girder bridge, and belongs to the technical field of bridge engineering. Longitudinal displacement of the top of a pier is an important control parameter for bridge design and construction, and too large longitudinal displacement of the top of the pier may cause risks of beam falling, reduction of anti-seismic performance of the bridge and the like and directly affects safety of bridge operation. A traditional pier top longitudinal displacement control method is achieved only by increasing the size of a pier structure or improving the material strength. The rigidity of the pier is utilized, and the longitudinal displacement of the pier top is further limited by increasing the longitudinal constraint boundary condition of the pier top. That is, the tops of the multiple piers are connected through the wires, so that the multiple piers are combined to cooperatively resist the longitudinal load of the top of a certain single pier, and the design requirement of the single pier can be reduced. According to the method, the light weight of the bridge pier column structure can be achieved, the construction cost is reduced, the anti-seismic property of the bridge is improved, and meanwhile the method has the advantages of being simple in process and wide in application range.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering technology, specifically relating to a method for controlling the longitudinal displacement of the top of the piers in a simply supported beam bridge. Background Technology

[0002] As the primary vertical load-bearing component in a bridge structure, the pier's fundamental function is to support the bridge superstructure and transfer the vertical loads generated by the superstructure to the foundation. In addition to this function, piers must also withstand longitudinal loads generated by earthquakes, temperature changes, and vehicle braking during service. Especially under seismic loads or vehicle braking, piers will experience significant longitudinal forces, resulting in corresponding longitudinal displacement at their tops. In simply supported beam bridges, excessive longitudinal displacement at the top of the pier not only negatively impacts the pier's own stress state but may also increase the relative displacement between the bridge superstructure and the pier, potentially leading to accidents such as beam collapse and affecting the normal operational safety of the bridge structure. For these reasons, longitudinal displacement at the top of the pier is one of the key indicators that needs to be controlled in bridge design.

[0003] In current engineering practice, whether for highway or railway bridges, existing technologies for controlling longitudinal displacement at the top of piers typically treat each pier as an independent load-bearing unit for mechanical analysis and design. Therefore, improving the longitudinal stiffness of a single pier and controlling its top longitudinal displacement usually only requires increasing the pier's cross-sectional dimensions or increasing the strength grade of the pier material. While this method can improve the ability of a single pier to resist longitudinal loads to some extent, its design philosophy is primarily based on the independent load-bearing of a single pier and does not fully consider the coordinated load-bearing of multiple piers. Consequently, bridge designs lack specific structural methods for the coordinated longitudinal load-bearing of multiple piers. Under engineering conditions with high requirements for controlling the longitudinal displacement at the top of piers, this method often necessitates significantly increasing the pier size or increasing the material strength grade to meet the control requirements. This not only makes the pier structure bulky but also increases construction difficulty and project cost. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling the longitudinal displacement of the top of the piers in a simply supported beam bridge, so that multiple piers can work together to resist possible longitudinal loads, thereby further reducing the design requirements of individual piers, and thus reducing project costs and construction difficulty.

[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0006] A method for controlling the longitudinal displacement of the pier top in a simply supported beam bridge. The longitudinal displacement of the pier top is controlled not only by the longitudinal stiffness of the pier itself but also by the additional longitudinal constraints applied to the pier top. This method, by adding additional longitudinal constraints to the pier top, alters the longitudinal force boundary conditions at the pier top, thereby transferring part of the longitudinal load to adjacent piers, abutments, or other anchorage boundaries. This allows multiple piers to jointly participate in the longitudinal load-bearing process, achieving multi-pier joint and coordinated resistance to the longitudinal load at the pier top, thus effectively limiting the pier top displacement under longitudinal load. The specific steps include:

[0007] Step S1: Based on the design load standard of the simply supported beam bridge, the seismic fortification intensity of the area where the bridge is located, the pier height and the bridge span, determine the longitudinal displacement control value of the top of the pier to be controlled and the maximum longitudinal load to be borne by the top of the pier to be controlled.

[0008] Step S2: Based on the longitudinal displacement control value determined in Step S1, and in conjunction with the structural dimensions, material parameters and structural form of the pier to be controlled, perform a longitudinal stress analysis on the pier to be controlled, and determine the longitudinal resistance value at the top of the pier that the pier can provide under the condition of satisfying the longitudinal displacement control value.

[0009] Step S3: Based on the maximum longitudinal load determined in step S1 and the longitudinal resistance value at the top of the pier determined in step S2, determine the tensile force value that the additional longitudinal constraint applied to the top of the pier needs to provide, so that the additional longitudinal constraint can compensate for the lack of longitudinal resistance of the pier itself, and resist the longitudinal load together with the pier and meet the displacement control requirements at the top of the pier.

[0010] Step S4: Based on the tensile force value required for the longitudinal constraint determined in Step S3, and in combination with the spatial conditions and construction feasibility of the top of the pier to be controlled, determine the material, specifications and quantity of the wire used to constrain the top of the pier, the anchoring method of the wire to the pier to be controlled, the magnitude of the wire tensioning force, and the fixing method of both ends of the wire.

[0011] Step S5: Carry out construction according to the results determined in step S4, install the wire passing through the top of the bridge pier or the cap beam, and anchor the wire to form an additional longitudinal constraint on the top of the bridge pier, so as to effectively control its longitudinal displacement.

[0012] Furthermore, the wire material mentioned in step S4 includes steel strand, reinforcing bar, high-strength steel wire, and fiber composite material. The anchoring method between the wire material and the pier to be controlled includes anchoring with wedge-type anchors or directly casting the wire material into the concrete of the pier top or cap beam.

[0013] Furthermore, in step S4, the two ends of the wire are fixed by anchoring both ends of the wire to the bridge abutments on both sides of the bridge. The construction in step S5 specifically includes the following contents or procedures: ① When constructing all piers and bridge abutments on both sides of the bridge, pre-drill holes are reserved for the wire to pass through; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ The wire is passed sequentially through the pre-drilled holes and anchoring components of each pier from one side of the bridge until it passes through the pre-drilled holes and anchoring components of the other abutment; ④ The wire is tensioned, and when the wire is tensioned to the magnitude of the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

[0014] Furthermore, in step S4, the two ends of the wire are fixed by anchoring them to the adjacent piers or abutments before and after the pier to be controlled. The construction in step S5 specifically includes the following contents or procedures: ① During the construction of the pier to be controlled and its adjacent piers or abutments, pre-drilled holes are reserved for the wire to pass through; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ The wire is passed through the pre-drilled holes and anchoring components of each pier or abutment in sequence; ④ The wire is tensioned, and when the wire is tensioned to the tensioning force determined in step S4, each anchoring component is locked and anchored to the wire.

[0015] Furthermore, in step S4, the two ends of the wire are fixed by anchoring both ends of the wire to the bridge abutments on both sides of the bridge, and anchoring components are only installed at the bridge abutments and some bridge piers. The construction in step S5 specifically includes the following contents or procedures: ① When constructing all bridge piers and bridge abutments on both sides of the bridge, pre-drill holes are reserved for the wire to pass through; ② Anchoring components for fixing the wire are installed only at both ends of the pre-drilled holes on the bridge abutments and some bridge piers; ③ The wire is passed sequentially through the pre-drilled holes and anchoring components of each bridge pier from one side of the bridge until it passes through the pre-drilled holes and anchoring components of the bridge abutment on the other side; ④ The wire is tensioned, and when the wire is tensioned to the magnitude of the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

[0016] Furthermore, in step S4, the two ends of the wire are fixed by anchoring them below the foundation, and the anchoring points at both ends of the wire are located on the axis of each pier. The construction in step S5 specifically includes the following contents or procedures: ① During the construction of all piers, pre-drilled holes are reserved for the wire to pass through; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ Anchoring components are installed at the anchoring points; ④ The wire is passed through the pre-drilled holes and anchoring components of each pier in sequence; ⑤ The wire is tensioned, and when the wire is tensioned to the magnitude of the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] This invention, by applying additional longitudinal constraints to the top of the bridge pier, alters the longitudinal force boundary conditions at the pier top. This effectively reduces the design requirements for individual piers while controlling longitudinal displacement at the pier top, resulting in smaller pier dimensions and lower material strength requirements. This method facilitates lightweighting of bridge pier structures, improving material utilization efficiency and engineering economy, while also offering advantages such as simple manufacturing process and wide applicability. Attached Figure Description

[0019] Figure 1 This is an elevation view of a simply supported beam bridge provided in Embodiment 1 of the present invention;

[0020] Figure 2 This is a three-dimensional diagram of a simply supported beam bridge provided in Embodiment 1 of the present invention;

[0021] Figure 3 This is an elevation view of the anchorage between the cap beam and the abutment of all piers of a simply supported beam bridge provided in Embodiment 1 of the present invention.

[0022] Figure 4 This is a three-dimensional schematic diagram of the anchorage between the cap beam and the abutment of all piers of a simply supported beam bridge provided in Embodiment 1 of the present invention.

[0023] Figure 5 This is a schematic elevation view of the anchorage of the upper cap beam of the bridge pier to be controlled and the adjacent bridge piers in front and behind in a simply supported beam bridge, provided in Embodiment 2 of the present invention.

[0024] Figure 6 This is a three-dimensional schematic diagram of the anchorage of the upper cap beam of the bridge pier to be controlled and the adjacent bridge piers in front and behind in a simply supported beam bridge, provided in Embodiment 2 of the present invention.

[0025] Figure 7 This is an elevation view of the anchorage between the cap beams on the upper part of all piers of a simply supported beam bridge and the foundation, provided in Embodiment 3 of the present invention.

[0026] Figure 8 This is a three-dimensional schematic diagram of the anchorage between the cap beams on the upper part of all piers of a simply supported beam bridge and the foundation, provided in Embodiment 3 of the present invention.

[0027] Figure 9 This is a three-dimensional schematic diagram of the anchorage at the top of the second span of a simply supported beam bridge provided in Embodiment 1 of the present invention;

[0028] Figure 10 This is a detailed drawing of the anchoring component provided in Embodiment 1 of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1-Pier No. ①; 2-Pier No. ②; 3-Pier No. ③; 4-Abutment; 5-Simply supported beam; 6-Cap beam; 7-Anchoring component; 8-Protective sleeve; 9-Steel strand; 10-Anchor ring; 11-Wedge; 12-Foundation. Detailed Implementation

[0031] To make the technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present invention, and are only used to explain the present invention, not to limit the present invention. It should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings. Other related parts can be referred to the general design. In the absence of conflict, the embodiments and technical features in the embodiments of the present invention can be combined with each other to obtain new embodiments.

[0032] It should be noted that this invention is a method for achieving the joint and coordinated resistance of multiple bridge piers to longitudinal loads and control the longitudinal displacement of the bridge pier tops by adding additional longitudinal constraints at the top of the piers. The bridge span arrangement, number and location of piers, structural form, material parameters, load rating, displacement control value, wire type, anchorage component type, tensioning force, and wire end fixing method involved in the following embodiments are all specific examples given to facilitate the explanation of the principle of this invention and do not constitute a limitation on the scope of this invention. In actual engineering, adjustments can be made according to the bridge structural form, stress characteristics, control objectives, and construction conditions.

[0033] It should also be noted that the determination of the longitudinal displacement control value at the top of the pier, the calculation of the longitudinal resistance value of the pier itself, the determination of the tensile force value required for additional longitudinal constraints, the selection of wire specifications and quantity, the calculation of tensioning preload, and the determination of anchorage method involved in the implementation of this invention can be accomplished using commonly used bridge structure analysis theories, design specifications, calculation methods, or numerical analysis methods in the field. The values ​​listed in the embodiments are only used to illustrate the implementation process and mechanism of action of this invention and should not be construed as limiting the scope of protection of this invention. In addition, the structural forms of steel strands, anchorage components, and protective sleeves described in the embodiments can all be achieved by adopting other equivalent measures according to the actual engineering situation. As long as a longitudinal constraint system can be formed at the top of the pier, multiple piers can be subjected to coordinated force, and the longitudinal displacement at the top of the pier can be effectively controlled, they all belong to the implementation of this invention.

[0034] Example 1:

[0035] The following is in conjunction with the appendix Figure 1 To be continued Figure 4 Appendix Figure 9 With appendix Figure 10 The present invention will be further described in detail in Embodiment 1.

[0036] like Figure 1 and Figure 2 The image shows a simply supported beam highway bridge. The bridge employs a four-span, uniform-section simply supported beam structure with a span combination of 20m+20m+20m+20m. The total length of the bridge is 94.54m, and the total width of the bridge deck is 14.0m (driving road) + 2×2.0m (pedestrian walkways). The design load is Highway-II, with a pedestrian load of 3.5kN / m². The bridge's seismic fortification category is Class C, the seismic fortification intensity is VII, the site is Class II, and the peak ground acceleration is 0.1g. The bridge superstructure consists of precast reinforced concrete T-beams, with 5 beams per span, each 2.0m high, constructed of C50 reinforced concrete. The bridge deck pavement consists of 10cm thick C50 waterproof concrete and 10cm thick asphalt concrete. The bridge substructure adopts double-column piers with spread foundations. The pier body has a rectangular cross-section and a calculated height of 10m. The pier foundation is a spread foundation with a thickness of 150cm and a width of 400cm, and is made of C30 rubble concrete. The abutment adopts a U-shaped gravity abutment with a cap thickness of 50cm and a width of 130cm. The back wall is 150cm high and 70cm thick. The abutment cap, back wall and side walls are all made of C30 reinforced concrete. The abutment foundation is a single-step 150cm thick C30 rubble concrete spread foundation.

[0037] Analysis shows that under longitudinal seismic loading, to meet the longitudinal displacement control requirements at the top of the pier, if a conventional pier design is adopted, the dimensions of pier 2 (No. 2) need to be designed as 160cm × 160cm using C40 concrete. To reduce the design requirements of a single pier, decrease the pier cross-sectional dimensions, and lower the material strength grade, achieving lightweight pier structure and improving material utilization efficiency and engineering economy, an additional longitudinal constraint is applied to the top of pier 2 to control its longitudinal displacement. In this embodiment, a longitudinal constraint system is formed by installing wires along the longitudinal direction of the bridge and anchoring them to the upper cap beams of all piers and the abutments on both sides of the bridge. Using this method, the dimensions of pier 2 (No. 2) can be reduced to 140cm × 140cm, and the concrete strength grade can be reduced to C30. The specific implementation steps are as follows:

[0038] Step S1 (Determine the longitudinal displacement control value and maximum longitudinal load at the top of the pier):

[0039] Based on the structural layout, pier construction, and potential longitudinal load conditions of the simply supported beam bridge, it was determined that the longitudinal displacement of the top of pier 2 (No. 2) is controlled by longitudinal seismic loading. Further analysis, considering the bridge's seismic fortification intensity, site conditions, and the dimensions and material parameters of simply supported beam 5 and pier 2 (No. 2), was performed according to the current "Code for Seismic Design of Highway Bridges JTG / T 2231-01". The allowable longitudinal displacement control value of the top of pier 2 (No. 2) under longitudinal seismic loading was determined to be 80.4 mm. Simultaneously, the maximum longitudinal load that pier 2 (No. 2) must bear under this loading condition was determined to be 4944.28 kN.

[0040] Step S2 (Determine the pier top resistance value provided by the pier itself):

[0041] Based on the structural form, geometric dimensions, and material parameters of Pier 2 (No. 2), a longitudinal stress analysis was performed on Pier 2. Pier 2 is a double-column pier with a cross-sectional dimension of 140cm × 140cm and a calculated height of 10m. It is constructed using C30 reinforced concrete. Based on the aforementioned structural dimensions and material parameters, the longitudinal lateral stiffness of Pier 2 was determined to be 57624kN / m. Combining this with the longitudinal displacement control value of 80.4mm at the top of Pier 2 determined in step S1, further calculations determined that, under the condition of meeting this displacement control requirement, Pier 2 itself can provide a longitudinal resistance value of 4631.38kN at the top of the pier.

[0042] Step S3 (Determine the tensile force required for the additional longitudinal constraint):

[0043] A comparative analysis was conducted based on the maximum longitudinal load of 4944.28 kN that pier 2 (number ②) needs to bear under longitudinal seismic action, determined in step S1, and the longitudinal resistance value of 4631.38 kN that pier 2 itself can provide at the pier top, calculated in step S2. The results show that, under the premise of meeting the longitudinal displacement control value at the pier top, the longitudinal resistance provided by pier 2 itself is insufficient to meet the requirements, and an additional longitudinal constraint of not less than 312.90 kN is still needed to provide resistance.

[0044] Step S4 (Determine the wire dimensions and constraint method used to constrain the top of the bridge pier):

[0045] Based on the calculated tensile force of 312.90 kN required for the additional longitudinal constraint applied to the top of the pier, as determined in step S3, and considering the structural form of pier 2 (No. 2), the spatial conditions at the top of the pier, and the feasibility of construction, high-strength steel strand 9 was selected as the wire material. The longitudinal constraint on the top of the pier was applied by continuously inserting precast holes along the longitudinal direction of the bridge into the upper cap beams 6 of all piers and the abutments 4 at both ends of the bridge, and fixing them with anchoring members 7 on both sides of the precast holes. Specifically, the connecting wire material is high-strength steel strand 1×3-10.80-1720-GB / T 5224-2023, with a nominal diameter of 10.80 mm, a nominal tensile strength of 1720 MPa, and a yield strength of 88.9 kN. Four strands of steel strand are connected between adjacent cap beams 6 in each span, with each strand consisting of three bundles of steel strand. Calculations show that the theoretical maximum tensile force provided by the installed steel strand 9 is 88.9 × 3 × 4 = 1066.8 kN, which can meet the tensile force requirements of the longitudinal constraint at the top of the pier. The steel strand 9 is arranged longitudinally along the bridge and is anchored and tensioned by anchoring members 7 installed at the cap beam 6 and abutment 4, resulting in a tensile force of approximately 320 kN in the steel strand 9. To improve the durability of the steel strand 9 during service, a protective sleeve 8 is installed around the outer periphery of the steel strand 9.

[0046] Step S5 (Construction Implementation):

[0047] According to the results determined in step S4, the construction is carried out as follows: (1) When constructing the upper cap beam 6 of all piers and the abutments 4 on both sides of the bridge, pre-fabricated holes are reserved for the steel strands 9 to pass through. The diameter of the pre-fabricated holes is 30mm, the hole walls are smooth and continuous, and the position of the pre-fabricated holes avoids the area where the main reinforcement and stirrups are arranged inside the cap beam 6 and the abutment 4, so as to meet the requirements for the steel strands 9 to pass through and subsequent construction; (2) If Figure 9 and Figure 10As shown, anchoring components 7 for fixing steel strands 9 are installed on both sides of the precast holes in each cap beam 6 and on the outside of the precast holes in the abutment 4. The anchoring components 7 include anchor rings 10 and clamps 11. The anchor rings 10 are made of high-strength alloy steel, and the clamps 11 are standard anchoring clamps that match the steel strands 9, which are used to achieve reliable anchoring and locking of the steel strands 9. (3) Steel strands 9 are laid out along the longitudinal direction of the bridge. After one end of the steel strands 9 is anchored to the abutment 4 on one side of the bridge through the anchoring components 7, the other end of the steel strands 9 passes through each protective sleeve 8, the precast holes in each cap beam 6 and the corresponding anchoring components in sequence. Component 7, until it extends to the abutment 4 on the other side of the bridge and is fixed. The protective sleeve 8 is made of corrosion-resistant steel pipe, and the inside can be used for steel strands 9 to pass through. Its two ends can be connected and fixed to the anchoring components 7 to prevent the steel strands 9 from rusting during service; (4) The steel strands 9 are tensioned by a through-hole jack. When the tension of the steel strands 9 reaches the tension of 320kN determined in step S4, the steel strands 9 are anchored and locked by each anchoring component 7; (5) The protective sleeve 8 is connected and fixed to the corresponding anchoring component 7 to complete the overall construction of the longitudinal restraint system at the top of the pier. The simply supported beam bridge after construction is as follows: Figure 3 and Figure 4 As shown.

[0048] Example 2:

[0049] The following is in conjunction with the appendix Figure 5 With appendix Figure 6 The present invention will be further described in detail in Embodiment 2.

[0050] The difference between Example 2 and Example 1 is that in this example, the ends of the steel strand 9 used to apply longitudinal restraint to the top of pier 2 are no longer anchored to the abutments 4 on both sides of the bridge, but are anchored to the upper cap beams 6 of piers 1 and 3, which are adjacent to pier 2, thus forming a longitudinal restraint system between locally adjacent piers. The remaining details, such as the calculation and analysis methods for steps S1 to S3, the form of the anchoring components, the specifications of the steel strands, and the tensioning method, can all refer to Example 1.

[0051] like Figure 5 and Figure 6 As shown, in this embodiment, based on the analysis results of steps S1 to S3, steel strand 9 is still used as the wire, and anchoring member 7 is used for fixing. Unlike embodiment 1, in this embodiment, the steel strand 9 passes sequentially along the longitudinal direction of the bridge through the pre-drilled holes and corresponding anchoring members 7 in the upper cap beams 6 of piers 1, 2, and 3, and is anchored to the upper cap beams 6 of piers 1 and 3.

[0052] During construction, prefabricated holes for steel strands 9 to pass through are reserved in the upper cap beams 6 of piers 1, 2, and 3, and anchoring components 7 for fixing the steel strands 9 are installed on both sides of each prefabricated hole. Then, the steel strands 9 are laid out longitudinally along the bridge, so that the steel strands 9 pass through each protective sleeve 8, the prefabricated holes in the upper cap beams 6 of each pier, and the corresponding anchoring components 7 in sequence. Next, the steel strands 9 are tensioned using a through-hole jack. When the tension on the steel strands 9 reaches 320kN, the steel strands 9 are anchored and locked through each anchoring component 7. Finally, the protective sleeves 8 are connected and fixed to the corresponding anchoring components 7.

[0053] In this embodiment, by setting up a longitudinal constraint system of steel strands between the pier to be controlled and its adjacent piers before and after it, the longitudinal displacement of the top of pier 2 is constrained and controlled by multiple piers working together to bear force.

[0054] Example 3:

[0055] The following is in conjunction with the appendix Figure 7 With appendix Figure 8 The present invention will be further described in detail in Embodiment 3.

[0056] The difference between Embodiment 3 and Embodiment 1 is that in this embodiment, the steel strands 9 used to apply longitudinal constraints to the top of the piers are no longer anchored to the abutments 4 on both sides of the bridge. Instead, they pass sequentially through the upper cap beams 6 of each pier along the longitudinal direction of the bridge, and the two ends of the steel strands 9 are anchored below the foundations 12 located on the axis of each pier, thereby forming a longitudinal constraint system between the tops of the piers. The remaining details, such as the calculation and analysis methods for steps S1 to S3, the form of the anchoring components, the specifications of the steel strands, and the tensioning method, can all refer to Embodiment 1.

[0057] like Figure 7 and Figure 8 As shown, in this embodiment, based on the analysis results of steps S1 to S3, steel strand 9 is still used as the wire, and anchoring member 7 is used for fixing. Unlike embodiment 1, in this embodiment, the steel strand 9 passes sequentially along the longitudinal direction of the bridge through the pre-fabricated holes reserved in the upper cap beam 6 of each pier and the corresponding anchoring member 7, and its two ends extend downward and are anchored to the foundation 12.

[0058] During construction, pre-cast holes for steel strands 9 to pass through are reserved in the upper cap beams 6 of each pier, and anchoring components 7 for fixing the steel strands 9 are installed on both sides of each pre-cast hole. At the same time, anchoring components 7 for anchoring the steel strands 9 are installed in the foundations 12 on both sides of the bridge. Then, the steel strands 9 are laid out longitudinally along the bridge, so that the steel strands 9 pass through each protective sleeve 8, the pre-cast holes in the upper cap beams 6 of each pier, and the corresponding anchoring components 7 in sequence, and the two ends of the steel strands 9 are connected and fixed to the anchoring components 7 installed in the foundations 12 respectively. Then, the steel strands 9 are tensioned using a through-hole jack. When the tension of the steel strands 9 reaches 320kN, the steel strands 9 are anchored and locked through each anchoring component 7. Finally, the protective sleeves 8 are connected and fixed to the corresponding anchoring components 7.

[0059] In this embodiment, by anchoring the two ends of the steel strand 9 to the foundation 12 located on the axis of each pier, a stable longitudinal constraint system is formed between the tops of each pier, enabling multiple piers to share the load, thereby constraining and controlling the longitudinal displacement of the top of pier 2.

Claims

1. A method for controlling the longitudinal displacement of the top of the piers in a simply supported beam bridge, characterized in that, Includes the following steps: Step S1: Based on the design load standard of the simply supported beam bridge, the seismic fortification intensity of the area where the bridge is located, the pier height and the bridge span, determine the longitudinal displacement control value of the top of the pier to be controlled and the maximum longitudinal load to be borne by the top of the pier to be controlled. Step S2: Based on the longitudinal displacement control value determined in step S1, and in conjunction with the structural dimensions, material parameters, and structural form of the pier to be controlled, determine the longitudinal resistance value provided by the pier top itself. Step S3: Based on the maximum longitudinal load determined in step S1 and the longitudinal resistance value at the top of the pier determined in step S2, determine the tensile force value that needs to be provided for the additional longitudinal constraint applied at the top of the pier. Step S4: Based on the tensile force value required for the longitudinal constraint determined in Step S3, determine the material, specifications and quantity of the wire used to constrain the top of the pier, the anchoring method between the wire and the pier to be controlled, the magnitude of the wire tensioning preload, and the fixing method at both ends of the wire. Step S5: Carry out the construction according to the results determined in step S4, install the wire passing through the top of the bridge pier or the cap beam, and anchor the wire.

2. The method for controlling the longitudinal displacement of the top of the piers of a simply supported beam bridge according to claim 1, characterized in that, The wire material mentioned in step S4 includes steel strand, reinforcing bar, high-strength steel wire, and fiber composite material. The anchoring method between the wire material and the pier to be controlled includes anchoring with wedge-type anchors or directly casting the wire material into the concrete on the top of the pier or the cap beam.

3. The method for controlling the longitudinal displacement of the top of the piers of a simply supported beam bridge according to claim 1, characterized in that, The fixing method of the two ends of the wire in step S4 is that the two ends of the wire are anchored to the bridge abutments on both sides of the bridge. The construction in step S5 specifically includes the following contents or procedures: ① When constructing all bridge piers and bridge abutments on both sides of the bridge, pre-drill holes for the wire to pass through are reserved; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ The wire is passed through the pre-drilled holes and anchoring components of each bridge pier in sequence from one side of the bridge until it passes through the pre-drilled holes and anchoring components of the bridge abutment on the other side; ④ The wire is tensioned, and when the wire is tensioned to the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

4. The method for controlling the longitudinal displacement of the top of the piers of a simply supported beam bridge according to claim 1, characterized in that, The fixing method of the two ends of the wire in step S4 is that the two ends of the wire are anchored to the piers or abutments adjacent to the pier to be controlled. The construction in step S5 specifically includes the following contents or procedures: ① When constructing the pier to be controlled and the piers or abutments adjacent to it, pre-drill holes for the wire to pass through are reserved; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ The wire is passed through the pre-drilled holes and anchoring components of each pier or abutment in sequence; ④ The wire is tensioned, and when the wire is tensioned to the tensioning force determined in step S4, each anchoring component is locked and anchored to the wire.

5. The method for controlling the longitudinal displacement of the top of the piers of a simply supported beam bridge according to claim 1, characterized in that, The fixing method of the two ends of the wire in step S4 is that the two ends of the wire are anchored to the bridge abutments on both sides of the bridge. The construction in step S5 specifically includes the following contents or procedures: ① When constructing all bridge piers and bridge abutments on both sides of the bridge, pre-drill holes for the wire to pass through are reserved; ② Anchoring components for fixing the wire are installed only at both ends of the pre-drilled holes in the bridge abutments and some bridge piers; ③ The wire is passed through each pre-drilled hole and each anchoring component in sequence from one side of the bridge until it passes through the pre-drilled hole and anchoring component on the other side of the bridge abutment; ④ The wire is tensioned, and when the wire is tensioned to the magnitude of the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

6. The method for controlling the longitudinal displacement of the top of the piers of a simply supported beam bridge according to claim 1, characterized in that, The fixing method of the two ends of the wire in step S4 is that the two ends of the wire are anchored below the foundation, and the anchoring points of the two ends of the wire are located on the axis of each pier. The construction in step S5 specifically includes the following contents or procedures: ① During the construction of all piers, pre-drill holes are reserved for the wire to pass through; ② Anchoring components for fixing the wire are installed at both ends of each pre-drilled hole; ③ Anchoring components are installed at the anchoring points; ④ The wire is passed through the pre-drilled holes and anchoring components of each pier in sequence; ⑤ The wire is tensioned, and when the wire is tensioned to the magnitude of the tensioning preload determined in step S4, each anchoring component is locked and anchored to the wire.

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