Hybrid connection steel casing assembly type rail transit pier and construction method thereof

Abstract

The application discloses a steel sleeve assembly type rail transit pier adopting mixed connection and a construction method thereof, and the pier structure can be assembled by a bearing platform, a pre-buried corrugated pipe, high-strength bolts, a steel sleeve, a flange connecting plate, a reinforced concrete pier body segment, prestressed tendons and energy dissipation steel bars; the bearing platform, the outer steel sleeve and the pier body segment are pre-fabricated in a factory, transported to a site, and sequentially connected in series by a mixed connection mode of grouting corrugated pipe connection, high-strength bolt flange connection and post-tensioned prestressed connection to form the pier, the flange connection is arranged at a joint position between different segments of the pier, the energy dissipation steel bars are deformed cooperatively with the pier, the opening and closing of the joint position at the bottom of the pier are controlled, the energy dissipation and shock absorption effect is played, different shock absorption requirements of the pier are met, the steel sleeve plays a role of buffering and shock absorption, and the collision damage of the concrete at the joint is reduced; thus, the application can improve the seismic performance level of the pre-fabricated assembly type pier and provides an important reference for the seismic design of the pier.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology, to prefabricated bridge pier vibration reduction technology, and particularly to a steel sleeve prefabricated rail transit bridge pier with hybrid connection and its construction method. Background Technology

[0002] Precast bridge piers have advantages such as reliable quality, standardized production, convenient construction, low environmental pollution and low energy consumption. However, they also have problems such as the segmental assembly joints being prone to opening under horizontal forces, poor integrity and deformation capacity, and weaker seismic performance than cast-in-place structures. Therefore, they can generally only be used in low-seismic zones, while their application is limited in medium and high-seismic zones.

[0003] Segmental piers are assembled from several pier segments connected by prestressed tendons. Longitudinal reinforcing bars are placed inside each segment, but these bars are discontinuous at the joints, making these joints the weakest points in the segmental pier. Existing research indicates that while segmental piers have smaller residual displacements and better self-centering capabilities compared to cast-in-place reinforced concrete piers, their hysteresis curves are significantly pinched, resulting in weaker energy dissipation capacity. Furthermore, their horizontal bearing capacity at the pier top is weaker than that of similar cast-in-place piers, limiting their widespread application in high-intensity seismic zones. To further improve the seismic performance of segmental piers and enhance their seismic safety in high-intensity areas, scholars both domestically and internationally have conducted in-depth research on vibration reduction measures for segmental piers.

[0004] Equivalent cast-in-place systems offer better integrity and energy dissipation capacity, while non-equivalent cast-in-place systems possess unique self-correcting capabilities. Combining these two deformation mechanisms in prefabricated bridge pier systems creates a hybrid system. This hybrid system, incorporating multiple connection methods, can simultaneously possess both good energy dissipation and self-correcting capabilities, thus improving the seismic performance of prefabricated bridge piers. However, the hybrid system also suffers from the inherent problems of both systems, such as the difficulty of repairing plastic hinges and the increased complexity of construction and maintenance due to the use of prestressed tendons.

[0005] Furthermore, under strong earthquakes, the segmental piers experience significant swaying motion, with violent collisions between different segments, resulting in obvious plastic damage to the concrete at the joints, which seriously affects the seismic safety of this type of pier.

[0006] Therefore, in view of the above-mentioned defects, the designers of this invention, through dedicated research and design, and by integrating years of experience and achievements in related industries, have researched and designed a steel sleeve prefabricated rail transit bridge pier with hybrid connection and its construction method to overcome the above-mentioned defects. Summary of the Invention

[0007] The purpose of this invention is to provide a steel-casing prefabricated rail transit bridge pier with hybrid connection and its construction method. The various prefabricated components of the pier are connected by multiple connection methods. Among them, the pier body segments are connected by high-strength bolts and flanges, the pier bottom and the abutment are connected by grouting corrugated pipes and energy-dissipating steel bars and flanges, and the pier body and the abutment are connected by post-tensioned prestressing. This provides the pier with self-resetting capability and effectively overcomes the defects of the prior art. It has important practical engineering application value and significance for the promotion and application of this type of bridge pier in high-intensity earthquake zones.

[0008] To achieve the above objectives, this invention discloses a steel-casing prefabricated rail transit bridge pier with hybrid connection, comprising a pier cap and multiple pier segments supported on the pier cap, characterized in that:

[0009] The multiple pier segments include a variable cross-section pier segment connected from top to bottom to form a complete pier, at least one straight pier segment, and a plastic hinge pier segment. The top of the pier is provided with multiple support pads, and the bottom of the pier is connected to the abutment. The pier segments are connected by a high-strength bolt flange structure. The bottom of the pier and the abutment are connected by a grouting corrugated pipe and an energy-dissipating steel flange structure. The pier and the abutment are connected by post-tensioned prestressing, thereby providing the pier with self-resetting capability.

[0010] Each pier segment is encased in a steel sleeve, and an extended flange is installed at the connection point of the steel sleeve.

[0011] Each pier segment and abutment is equipped with prestressed ducts for the prestressing tendons to pass through.

[0012] Among them, a high-strength mortar cushion layer is provided between the pier body and the foundation.

[0013] Among them, the flanges of the steel sleeves between the pier segments are connected by high-strength bolt connection components, and multiple connection holes are provided at intervals around the two flanges for the high-strength bolt connection components to pass through and connect.

[0014] Specifically: the plastic hinge pier segment at the bottom of the pier body is connected to the pier cap. The pier cap has multiple energy-dissipating steel bars around the flange of the steel sleeve corresponding to the plastic hinge pier segment. The multiple energy-dissipating steel bars pass through the flange and are fixed by fastening nut assembly. The pier cap has multiple embedded metal corrugated pipes inside the energy-dissipating steel bars. The bottom of the plastic hinge pier segment has multiple anchoring steel bars that can extend into the embedded metal corrugated pipes.

[0015] Wherein: a pre-embedded metal corrugated pipe is pre-embedded in the middle of the pier segment, thereby forming a prestressed reserved hole in the middle of the pier segment after prefabrication.

[0016] Among them: the connecting end of the pier segment is provided with multiple grouting pipes, so that after prefabrication, grouting channels and grout outlet channels are formed at the connecting end of the pier segment respectively. One end of the grouting pipe is flush with the side of the steel sleeve, and the other end is flush with the surface of the concrete inside the prefabricated pier segment. The grouting pipe is L-shaped.

[0017] A construction method for prefabricated rail transit bridge piers using a hybrid connection steel sleeve is also disclosed, characterized by the following construction steps:

[0018] Step 1: Complete the factory prefabrication of the foundation and multiple pier segments;

[0019] Step 2: Assemble the bottom pier segment with the foundation. First, match and assemble the segments, and lay grout-blocking templates around the joints. Then, level the adjusting pads placed at the joints and lay a high-strength mortar cushion layer. Next, hoist the bottom pier segment and connect it to the foundation through a grouting corrugated metal pipe. One end of the prestressing tendon is anchored to the bottom of the foundation, and the other end passes through the foundation and the bottom pier segment through a reserved hole, connecting the two together to complete the assembly of the bottom pier and the foundation.

[0020] Step 3: Proceed to the next pier segment assembly. Hoist the next pier segment to the designated height and then slowly lower it to the designated position. Measure, control, and adjust its verticality and elevation to meet accuracy requirements. Install the connecting bolt assembly. During the prefabrication of the pier segment, a 20mm gap is left between the top surface of the internal concrete and the top surface of the flange. Grouting and discharge channels are reserved at the top and bottom of the pier segment, respectively. The corresponding grouting and discharge channels are located on the top and bottom sides of the pier segment. After the flange connection is completed, grout the joints between the pier segments to ensure complete contact between the two connecting surfaces at the joint, thereby ensuring the uniformity of force transmission in the pier. The prestressing tendons are connected to the previously assembled portion along the reserved channels in the center of the pier segment, completing the assembly of the second pier segment. Following the above assembly process, install the remaining straight pier segments and variable cross-section pier segments in sequence.

[0021] Step 4: After the assembly is completed, use anchorages to anchor and tension the prestressed tendons in the pre-reserved anchorage grooves on the top surface of the variable cross-section pier segment to form a post-tensioned prestressed connection. Then, fill the anchorage grooves with cement mortar to complete the on-site assembly of the pier.

[0022] Step 5: Complete the flange connection of the energy-dissipating steel bars between the bottom of the pier and the abutment. Drill and clean the abutment at the flange connection hole of the bottom pier segment, then inject adhesive into the hole to carry out the rebar installation operation, insert the energy-dissipating steel bars, install the nut connection assembly on the top of the energy-dissipating steel bars and tighten it to the specified torque to complete the flange connection of the energy-dissipating steel bars between the bottom of the pier and the abutment.

[0023] The prefabrication of each pier segment in step 1 includes the following sub-steps:

[0024] Step 1.1: Cutting and processing of reinforcing bars and steel plates;

[0025] Step 1.2: Weld the steel sleeves of the pier segments, weld the processed steel sleeves into a whole, and weld flanges at the connection ends of the steel sleeves. For the steel sleeves of the variable cross-section pier segments, only the lower end needs to be welded with flanges, and the others are welded at both ends.

[0026] Step 1.3: Tie the reinforcing cage and lay the prestressed ducts;

[0027] Step 1.4: Formwork erection. The corresponding segment steel sleeve is directly used as the steel formwork for the pier body. After the formwork is erected, the verticality of the pier needs to be adjusted again, and stiffening steel supports are used to support the steel formwork on the outside to ensure that the pier body formwork does not deform, tilt or rotate during the pouring and curing process, and remains perpendicular to the horizontal plane.

[0028] Step 1.5: Hoist the reinforcing steel cage and hoist the tied reinforcing steel cage into the steel sleeve formwork;

[0029] Step 1.6: Concrete pouring and component curing.

[0030] The prefabrication of the foundation in step 1 includes the following sub-steps:

[0031] Step 1.1: Steel bar cutting and processing;

[0032] Step 1.2: Tie the reinforcing cage and lay the prestressed ducts;

[0033] Step 1.3: Formwork erection. The foundation should be square in size. The formwork should be made of wood and reinforced with tie rods after installation.

[0034] Step 1.4: Hoist the steel reinforcement cage and hoist the tied steel reinforcement cage into the erected formwork;

[0035] Step 1.5: Concrete pouring and component curing;

[0036] Step 1.6: Demolding and curing of components.

[0037] Step 3 includes: assembling the next pier segment. First, the prestressing ducts should be sealed with expansion sealing strips on the top surface of the concrete of the previous pier segment to prevent grout from seeping into the prestressing ducts during subsequent grouting. The connecting surfaces of the upper and lower pier segments should be cleaned. The level of the top flange of the previous pier segment should be measured and the gaskets adjusted. The next pier segment should be hoisted to the designated position, and its verticality and elevation should be measured, controlled, and adjusted. After meeting the accuracy requirements, the connecting bolt assembly should be installed, and all high-strength connecting bolts should be tightened to the specified torque according to the design standards. The pier segment lifting equipment should be removed, and the guide ropes should be untied.

[0038] As can be seen from the above, the steel sleeve prefabricated rail transit bridge pier with hybrid connection and its construction method of the present invention have the following effects:

[0039] 1. By applying high-performance materials and novel connection devices to segmental piers, and combining the advantages of different pier connection structures to form a hybrid seismic-resistant system, the seismic performance of segmental piers is improved. This initially achieves the goal of controllable seismic damage and rapid post-earthquake repair for segmental piers, effectively improving their seismic safety. From the perspective of the entire life cycle of bridges, this new structural system has high practical engineering application value and superior economic benefits.

[0040] 2. The connection structure is simple and easy to design, and it is also easy to install and replace after an earthquake. Under minor earthquakes, the energy-dissipating steel bar deforms little and remains in an elastic state, which can not only control the displacement response of the pier, but also provide a certain elastic restoring force for the pier. Under major earthquakes, the energy-dissipating steel bar deforms significantly and enters an elastoplastic state, consuming the energy input to the pier by the earthquake.

[0041] 3. Controlling the bonding anchorage length (adhesive injection depth) during the installation of energy-dissipating steel bars can facilitate partial debonding of the energy-dissipating steel bars, thereby avoiding stress concentration, improving the plastic deformation at the joint at the bottom of the pier, further enhancing the deformation and energy dissipation capacity of the pier, and reducing residual displacement.

[0042] 4. High-strength bolt-flange connections are used between pier segments, which can effectively resist shear stress at the joints, avoid shear failure of the structure, and improve the shear resistance and energy dissipation performance of the segmental prefabricated pier.

[0043] 5. Under strong earthquake action, when the energy-dissipating steel bars enter the elastoplastic working state, the flange connection plate at the bottom of the pier will also deform and dissipate energy. At the same time, the presence of the flange connection plate at the bottom of the pier also enhances the overturning resistance of the pier body. The energy-dissipating steel bar-flange connection structure at the bottom of the pier significantly improves the initial stiffness and post-yield stiffness of the precast swaying system, which can effectively prevent large displacement response or even collapse of precast assembled piers, thereby preventing the occurrence of beam falling earthquake damage.

[0044] 6. The outer steel sleeve and its end flange are made entirely of steel, which facilitates factory production and ensures efficiency and quality. The bottom plate of the steel sleeve of the plastic hinge pier segment (pier bottom segment) is drilled according to the position of the extended anchoring steel bar. During the factory prefabrication stage, it can provide accurate positioning for the extended anchoring steel bar at the pier bottom. It is not easy to deviate during the manufacturing process, which effectively ensures accurate alignment with the pre-embedded metal corrugated pipe of the pier cap during on-site assembly.

[0045] 7. The steel sleeves of the precast pier segments can protect and dampen the pier segments when they collide, reduce plastic damage to the concrete at the joints between different segments, enhance the restraint on the plastic hinge segments of the pier, and, combined with post-tensioned prestressed connections, effectively control the residual displacement of the precast segment pier after strong earthquakes, ensure the self-resetting ability of the precast segment pier, and improve the overall seismic performance and energy dissipation capacity of the precast segment pier.

[0046] The details of this invention will become apparent from the following description and the accompanying drawings. Attached Figure Description

[0047] Figure 1 This diagram shows the overall structure of the steel sleeve prefabricated rail transit bridge pier using a hybrid connection according to the present invention.

[0048] Figure 2 Showing Figure 1 The front view.

[0049] Figure 3 Showing Figure 1 Side view.

[0050] Figure 4 Showing Figure 1 Top view.

[0051] Figure 5A The diagram shows the connection between the plastic hinged pier segment and the pier cap in this invention.

[0052] Figure 5B Showing Figure 5A A diagram showing another direction.

[0053] Figure 6A A schematic diagram of the connection between segments in this invention is shown.

[0054] Figure 6B Showing Figure 6A Enlarged diagram in the image.

[0055] Figure 7A A front view of the invention is shown.

[0056] Figure 7B Showing Figure 7A A sectional view along line AA in the diagram.

[0057] Figure 7C Showing Figure 7A A sectional view along the BB direction.

[0058] Figure 8A Showing Figure 7A A sectional view along the BB direction.

[0059] Figure 8B Showing Figure 8A A cross-sectional view along the CC direction.

[0060] Figure 8C Showing Figure 8A A sectional view along the DD direction.

[0061] Figure 8D Showing Figure 8A A sectional view along the EE direction.

[0062] Figure 8E Showing Figure 8A Sectional view along the FF direction.

[0063] Figure 8F Showing Figure 8A A cross-sectional view along the GG direction.

[0064] Figure 8G Showing Figure 8A A cross-sectional view along the HH direction.

[0065] Figure 8H Showing Figure 8A Sectional view along the central II direction.

[0066] Figure 8I Showing Figure 8A A cross-sectional view along the JJ direction.

[0067] Figure 9A , Figure 9B , Figure 9C and Figure 9D A schematic diagram of the segmental assembly joint grouting structure in this invention is shown.

[0068] Figure 10A The diagram shows a top view of the pier base segment and the pier cap after assembly in this invention.

[0069] Figure 10B Showing Figure 10A A cross-sectional view along the KK direction.

[0070] Figure 10C Showing Figure 10A Sectional view along the LL direction.

[0071] Figure 10D Showing Figure 10C An enlarged diagram of A in the diagram.

[0072] Figure 10E Showing Figure 10B Enlarged diagram of B in the diagram.

[0073] Figure 11A A schematic diagram of the bolted flange connection in this invention is shown.

[0074] Figure 11B Showing Figure 11A An enlarged diagram of C in the diagram.

[0075] Figure 11C Showing Figure 11A An enlarged schematic diagram of D in the diagram.

[0076] Figure 12A , Figure 12B , Figure 12C and Figure 12D The diagram shows the structure of the steel sleeve on the variable cross-section pier segment in this invention.

[0077] Figure 13A , Figure 13B , Figure 13C and Figure 13D The diagram shows a structural schematic of the steel sleeve on the straight pier segment in this invention.

[0078] Figure 14A , Figure 14B , Figure 14C and Figure 14D The diagram shows a structural schematic of the steel sleeve on the plastic hinged pier segment in this invention.

[0079] Figure label:

[0080] 1-Supporting pad, 2-Variable cross-section pier segment, 3-Straight pier segment, 4-Plastic hinge pier segment, 5-Pile cap, 6-High-strength mortar pad, 7-Prestressed tendon top anchorage, 8-Steel sleeve (steel plate encasing reinforced concrete pier), 9-Prestressed tendon, 10-Prestressed reserved duct, 11-Flange, 12-High-strength bolt connection assembly, 13-Energy dissipating reinforcement, 14-Fastening nut assembly, 15-Anchoring reinforcement 16- Embedded metal corrugated pipe in the pier cap; 17- Prestressed tendon anchorage at the bottom of the pier cap; 18- Grouting conduit; 19- Grout outlet hole; 20- Embedded metal corrugated pipe in the pier body; 21- Grouting hole; 22- Micro-expansion cement mortar grouting material; 23- Pier cap rebar anchoring hole; 24- Flange stiffening rib; 25- Anchor rebar positioning hole; 26- Energy dissipating rebar positioning hole; 27- Grouting channel; 28- Grout outlet channel; 29- Reserved filling space for segment joint. Detailed Implementation

[0081] See Figures 1 to 14DThis invention demonstrates the prefabricated rail transit bridge pier with hybrid connection steel sleeve and its construction method.

[0082] Figures 1 to 4 The diagram shows a structural schematic of a steel-casing prefabricated rail transit bridge pier with hybrid connection according to the present invention. As shown in the figure, the steel-casing prefabricated rail transit bridge pier with hybrid connection includes a pier cap 5 and multiple pier segments supported on the pier cap. The multiple pier segments may include a variable cross-section pier segment 2 connected from top to bottom to form a complete pier, at least one straight pier segment 3, and a plastic hinge pier segment 4. The top of the pier (i.e., the top of the variable cross-section pier segment 2) is provided with multiple support pads 1, and the bottom of the pier (i.e., the bottom of the plastic hinge pier segment 4) is connected to the pier cap 5. The rail transit bridge pier of the present invention is connected by multiple connection methods. Among them, the pier segments are connected by a high-strength bolt flange structure, and the bottom of the pier and the pier cap are connected by a grouting corrugated pipe and an energy-dissipating steel flange structure. The pier and the pier cap are connected by post-tensioned prestressing, thereby providing the pier with self-resetting capability.

[0083] Each pier segment is encased in a steel sleeve 8 (i.e., a steel plate encasing the reinforced concrete pier body), and an extended flange 11 is installed at the connection points of the steel sleeve. This allows the steel sleeve 8 to be directly used as formwork for the pier segments during the factory prefabrication stage, eliminating the need for demolding and improving efficiency. Furthermore, the confinement effect of the steel sleeve on the core concrete enhances the load-bearing capacity of the prefabricated pier. Under strong earthquakes, it effectively confines the plastic hinge zone, enhancing the pier's deformation capacity and improving seismic performance. Simultaneously, the presence of the steel sleeve ensures the reliability of the flange connections between pier segments, improving the overall integrity of the prefabricated pier. In addition, the steel sleeve provides excellent protection for the concrete at the joints, preventing impact damage and plastic damage at the joints under seismic loading.

[0084] A high-strength mortar cushion layer 6 is provided between the pier body and the foundation, and a prestressed tendon pier head top sealing anchor 7 is provided at the top of the pier body, and a prestressed tendon anchoring end 17 is provided at the bottom of the foundation.

[0085] like Figure 6A Figure 6B As shown, see also Figure 7A , Figure 7B and Figure 7C The flanges 11 of the steel sleeves 8 between each pier segment are connected using high-strength bolt connection assemblies 12. Multiple connection holes for the high-strength bolt connection assemblies 12 to pass through are provided at intervals around the periphery of the two connecting flanges 11. This periphery connection of the high-strength bolt connection assemblies 12 effectively improves the shear resistance at the joint, and also provides energy dissipation and vibration reduction after the bolts yield under strong earthquakes. The size and arrangement of the high-strength bolts can be adjusted according to seismic requirements.

[0086] Each pier segment is equipped with a prestressed reserved hole 10 for the prestressed tendons 9 to pass through.

[0087] like Figure 5A , Figure 5B As shown, see also Figure 7A , Figure 7B and Figure 7C ,as well as Figures 8A to 8I ,as well as Figures 10A to 10E The plastic hinge pier segment 4 at the bottom of the pier body is connected to the pier cap 5. The pier cap 5 is provided with multiple energy-dissipating steel bars 13 around the flange of the steel sleeve of the plastic hinge pier segment 4. The multiple energy-dissipating steel bars 13 pass through the flange and are fixed by fastening nut assembly 14. The pier cap 5 has multiple pier cap embedded metal corrugated pipes 16 embedded inside the energy-dissipating steel bars 13. The bottom of the plastic hinge pier segment 4 is provided with multiple anchoring steel bars 15 that can extend into the pier cap embedded metal corrugated pipes 16 for a certain distance. The anchoring steel bars 15 are prefabricated and anchored through the entire segment of the plastic hinge pier segment 4.

[0088] Therefore, two methods are used to connect the pier base and the abutment. The first is a corrugated pipe grouting connection, using ultra-high performance concrete (UHPC) as the grout to ensure anchorage reliability. Simultaneously, large-diameter anchoring steel bars are used for connection, effectively reducing the number of pre-reserved corrugated pipe channels and lowering on-site construction difficulty. The second method uses energy-dissipating steel bars and flanges for connection. This method also reduces on-site construction difficulty. Using energy-dissipating steel bars can reduce joint curvature under seismic loads, inhibit joint opening, and improve the pier's strength, stiffness, and energy dissipation capacity.

[0089] The energy-dissipating steel bars are installed using a rebar anchoring method, eliminating the need for pre-embedded connectors, thus reducing the amount of prefabrication work and precision requirements in the factory, while also simplifying on-site assembly and connection. The external flange connection facilitates the installation and post-earthquake replacement of the energy-dissipating steel bars.

[0090] The center of the pier cap 5 also has a pre-reserved pre-stressed duct 10 for the prestressing tendons 9 to pass through, enabling post-tensioning prestressing connection. This allows the prefabricated pier to have self-resetting capability under prestress and its own weight, resulting in small residual displacement. The residual displacement of the non-equal cast-in-place system is caused by the plastic deformation of the joint. Due to the presence of the steel sleeve, the plastic deformation at the joint is smaller than that of the traditional connection method, thus the residual displacement is also smaller. This better reflects the concept of tough seismic resistance.

[0091] like Figures 9A to 9D As shown, a corrugated metal pipe 20 (such as...) is pre-embedded in the middle of the pier segment. Figure 9A As shown), thus after prefabrication (such as...) Figure 9BAs shown, a prestressed reserved duct 10 is formed in the middle of the pier segment (the prestressed reserved duct 10 of the pier cap 5 can also be set in the same way). Multiple grouting conduits 18 are provided at the connecting end of the steel sleeve 8 of the pier segment. One end of each grouting conduit 18 is flush with the side of the steel sleeve 8, and the other end is flush with the surface of the concrete inside the precast pier segment. The grouting conduit 18 is... Figure 9D The L-shape shown has a rounded transition in the middle.

[0092] Among them, such as Figure 9D As shown, the grouting conduit 18 above the segmental connection joint extends from the side of the steel sleeve 8 to form a grout outlet 19, and the grouting conduit 18 below extends from the side of the steel sleeve 8 to form a grouting hole 21. After the flange connection is completed, the connection joint between the pier segments is grouted. Specifically, the grouting machine outlet is connected to the grouting hole 21, and micro-expansion cement mortar grouting material 22 is injected through the grouting channel 27 formed by the pre-embedded grouting conduit 18 at the top of the lower pier segment, filling the reserved space 29 in the segmental connection joint. The excess micro-expansion cement mortar grouting material 22 will flow out from the grout outlet 19 through the grout outlet channel 28 formed by the pre-embedded grouting conduit 18 at the bottom of the upper pier segment. Then, the grout outlet is sealed, pressure is maintained, and the grouting hole is sealed again to complete the segmental connection joint grouting operation. This ensures that the two connecting surfaces at the pier segment joint are completely fitted, thereby ensuring the uniformity of force transmission in the pier.

[0093] like Figures 10A to 10E As shown, the lower end of the energy-dissipating steel bar 13 is pre-embedded in the foundation anchoring hole 23 of the foundation 5, and the upper end forms an external thread for fastening with the fastening nut assembly 14. The fastening nut assembly 14 includes two nuts that are screwed in sequence, and the anchoring steel bar 15 is embedded in the foundation pre-embedded metal corrugated pipe 15.

[0094] like Figure 11A , Figure 11B and Figure 11C As shown, the flange 11 is provided with a plurality of triangular flange stiffening ribs 24.

[0095] in, Figure 12A , Figure 12B , Figure 12C and Figure 12D This shows a schematic diagram of the steel sleeve structure on the variable cross-section pier segment in this invention. Figure 13A , Figure 13B , Figure 13C and Figure 13D This shows a schematic diagram of the steel sleeve structure on the straight pier segment in this invention. Figure 14A , Figure 14B , Figure 14C and Figure 14DThe diagram shows the structure of the steel sleeve on the plastic hinge pier segment of the present invention. Each steel sleeve 8 is a frame structure with an upper opening and a bottom plate. The middle two sides are provided with recessed fixing parts. The bottom plate of the steel sleeve 8 of the plastic hinge pier segment is provided with a plurality of anchoring steel bar positioning holes 25 and energy dissipation steel bar positioning holes 26.

[0096] Preferably, the high-strength bolt is a 12.9 grade M20 high-strength bolt.

[0097] Preferably, the energy-dissipating steel bars are made of Q235 steel to better perform their energy-dissipating and vibration-damping functions.

[0098] More importantly, this invention also discloses a construction method for the above-mentioned steel sleeve prefabricated rail transit bridge piers using hybrid connections, which may include the following construction steps:

[0099] Step 1: Complete the factory prefabrication of the foundation and multiple pier segments.

[0100] The prefabrication of each pier segment includes the following sub-steps:

[0101] Step 1.1: Cutting and processing of steel bars and steel plates. Cut the steel bars and steel plates according to the design drawings and process them into shape.

[0102] Step 1.2: Weld the steel sleeves of the pier segments. Weld the processed steel sleeves into a whole, and weld flanges to the joints of the steel sleeves. For the variable cross-section pier segments, only the lower end of the steel sleeve needs to be welded with a flange; the others are welded at both ends.

[0103] Step 1.3: Binding the reinforcing cage and laying the prestressed ducts. During the binding process, positioning bars need to be installed to facilitate the alignment of the reinforcing bars. When binding the reinforcing bars, the position of the prestressed ducts and embedded corrugated pipes needs to be considered. At the same time, appropriate steel mesh should be arranged under the anchor plate to prevent local crushing of the concrete.

[0104] Step 1.4: Formwork erection. The corresponding segment steel sleeves are directly used as steel formwork for the pier body. After the formwork is erected, the verticality of the pier needs to be readjusted, and stiffening steel supports are used to support the steel formwork on the outside to ensure that the pier body formwork does not deform, tilt or rotate during the pouring and curing process, and remains perpendicular to the horizontal plane.

[0105] Step 1.5: Hoisting the Rebar Cage. Hoist the tied rebar cage into the steel sleeve formwork. After hoisting into place, adjust any local deformations (including the spacing of the rebars, the thickness of the protective layer, and the position of the embedded parts) to ensure that the rebar cage is in good condition.

[0106] Step 1.6: Concrete Pouring and Component Curing. After the above work is completed, the component is poured. After pouring, the positioning of the reserved reinforcing bars and grouting corrugated metal pipes should also be checked.

[0107] Step 1.7: Formwork Removal and Curing of Components. After the concrete reaches a certain strength, remove the outer supporting steel frame of the pier segment; the outer steel plate does not need to be removed. Cover the concrete surface with a water-covered film and then spray water for curing at room temperature until the specified strength is achieved.

[0108] The prefabrication of the foundation includes the following sub-steps:

[0109] Step 1.1: Steel bar cutting and processing. Cut the steel bars according to the design drawings and process them into shape.

[0110] Step 1.2: Tying the reinforcing cage and laying the prestressed ducts. During the tying process, positioning bars need to be installed to facilitate the alignment of the reinforcing bars. When tying the reinforcing bars, the position of the prestressed ducts and embedded corrugated pipes needs to be considered. At the same time, appropriate steel mesh should be arranged under the anchor plate to prevent local crushing of the concrete.

[0111] Step 1.3: Formwork erection. The foundation is square in size, and the formwork is made of wood. After installation, it is reinforced with tie rods.

[0112] Step 1.4: Hoisting the Reinforcing Steel Cage. Hoist the tied reinforcing steel cage into the erected formwork. After hoisting into place, adjust any local deformations (including the spacing of the reinforcing bars, the thickness of the protective layer, and the position of the embedded parts) to ensure that the reinforcing steel cage is in good condition.

[0113] Step 1.5: Concrete Pouring and Component Curing. After the above work is completed, the component is poured. After pouring, the positioning of the reserved reinforcing bars and grouting corrugated metal pipes should also be checked.

[0114] Step 1.6: Formwork Removal and Curing of Components. After the concrete reaches a certain strength, remove the foundation formwork, cover the concrete surface with a water-covered film, sprinkle water, and cure at room temperature until the specified strength is achieved.

[0115] The prefabricated foundations and multiple pier segments can then be transported to the construction site for assembly.

[0116] Step 2: Assemble the lowest pier segment (i.e., the plastic hinge pier segment) with the foundation. First, perform matching assembly, measure the joint (i.e., the location of the high-strength mortar cushion layer), and lay grout-blocking templates around the joint. Then, level the adjusting blocks placed at the joint and lay the high-strength mortar cushion layer 6. Next, hoist the bottom pier segment, measure and adjust the verticality and elevation of the precast pier segment after positioning to ensure positioning accuracy. Finally, connect the grouting corrugated metal pipes. Connect the anchoring steel bars extending from the bottom of the pier segment through the pre-embedded corrugated metal pipes in the foundation, and fill the gap between the steel bars and the corrugated metal pipes with high-strength, non-shrink cement grout. Then seal the grouting holes 21 and grout outlet 19. After hardening, the anchoring steel bars are anchored, thus forming the grouting corrugated pipe connection structure between the pier and the foundation. Prestressed tendon ducts are pre-reserved in the center of the pier segment. The prestressed tendons are connected together along the reserved ducts to link the pier cap and the bottom pier segment, thus completing the assembly of the pier and the pier cap.

[0117] Step 3: Before assembling the next pier segment, first seal the prestressing ducts around the top concrete surface of the previous pier segment with expansion sealing strips to prevent grout from seeping into the prestressing ducts during subsequent grouting. Clean the connection surfaces of the upper and lower pier segments; wash away any debris adhering to the horizontal end face of the mating flange with pressurized water and allow it to dry. Measure the levelness of the top flange of the previous pier segment and level the gaskets. Hoist the next pier segment. After hoisting to the designated height, workers near the connection surface should align it with the positioning pins and slowly lower it to the designated position. Measure, control, and adjust its verticality and elevation to meet accuracy requirements. Immediately install the connecting bolt assembly and tighten all high-strength connecting bolts to the specified torque according to design standards. Remove the pier segment lifting equipment and disconnect the guide ropes. During the prefabrication of pier segments, a 20mm gap is left between the top surface of the poured concrete and the top surface of the flange. Grouting holes and outlet holes are provided on the top side of the steel sleeve. After the flange connection is completed, grouting is performed on the joints between the pier segments to ensure complete adhesion between the two connecting surfaces at the joint, thereby ensuring uniform force transmission in the pier. Micro-expansion cement mortar is injected through the pre-reserved grouting holes on the side of the steel sleeve, and then the grouting holes and outlet holes are sealed. After complete hardening, the next construction step can proceed. The prestressing tendons are connected in series with the previously assembled portion along the pre-reserved holes in the center of each pier segment, completing the assembly of the second pier segment. Following the above assembly process, the remaining straight and variable cross-section pier segments are installed sequentially, with the prestressing tendons passing through the pre-reserved holes in the center of each pier segment during assembly.

[0118] Step 4: After the assembly is completed, use anchorages to anchor and tension the prestressed tendons in the pre-reserved anchorage grooves on the top surface of the variable cross-section pier segment to form a post-tensioned prestressed connection. Then, fill the anchorage grooves with cement mortar to complete the on-site assembly of the pier.

[0119] Step 5: Complete the flange connection of the energy-dissipating steel bars between the pier bottom and the abutment. Based on the seismic requirements of segmented precast rail transit piers located in different seismic fortification zones, determine the type and size of the energy-dissipating steel bars, as well as their reasonable arrangement at the joint between the abutment and the bottom pier segment. This determines the design dimensions and opening positions of the flanges for the bottom pier segments. Drill and clean the abutment at the flange connection holes of the bottom pier segments, then inject adhesive into the holes for rebar installation. The exposed ends of the energy-dissipating steel bars are pre-tapping to facilitate later installation and connection. After the adhesive has cured, conduct a non-destructive pull-out test to check the quality of the rebar installation under working conditions. The number of rebars tested is 10% of the total number of rebars. After passing the test, install nuts on the top of the energy-dissipating steel bars and tighten them to the specified torque, completing the flange connection of the energy-dissipating steel bars between the pier bottom and the abutment.

[0120] Compared with the prior art, the advantages of the present invention are as follows:

[0121] 1. This energy-consuming steel bar connection method has a simple structure, is easy to design, and is easy to install and replace after an earthquake.

[0122] 2. Under minor earthquakes, the energy-dissipating steel bar deforms minimally and remains in an elastic state, which not only controls the displacement response of the pier but also provides a certain elastic restoring force to the pier. Under major earthquakes, the energy-dissipating steel bar deforms significantly and enters an elastoplastic state, consuming the energy input to the pier by the earthquake.

[0123] 3. By controlling the bonding anchorage length (adhesive injection depth) during the installation of energy-dissipating steel bars, partial debonding of the energy-dissipating steel bars can be easily achieved, thereby avoiding stress concentration, improving the plastic deformation at the joint at the bottom of the pier, further enhancing the deformation and energy dissipation capacity of the pier, and reducing residual displacement.

[0124] 4. High-strength bolt-flange connections are used between pier segments, which can effectively resist shear stress at the joints, avoid shear failure of the structure, and improve the shear resistance and energy dissipation performance of the segmental prefabricated pier.

[0125] 5. Based on the seismic requirements of precast and assembled rail transit bridge piers in different seismic fortification zones, the parameters, dimensions, and arrangement of energy-dissipating steel bars can be adjusted. Under strong earthquakes, when the energy-dissipating steel bars enter the elastoplastic working state, the flange connection plate at the bottom of the pier will also deform and dissipate energy. At the same time, the presence of the flange connection plate at the bottom of the pier also enhances the overturning resistance of the pier body. The energy-dissipating steel bar-flange connection structure at the bottom of the pier significantly improves the initial stiffness and post-yield stiffness of the precast swaying system, which can effectively prevent large displacement responses or even collapse of precast and assembled bridge piers, thereby preventing the occurrence of beam fall damage.

[0126] 6. The pier body is made entirely of steel, including the outer steel sleeve and the end flanges, which facilitates factory production and ensures efficiency and quality.

[0127] 7. The bottom plate of the steel sleeve of the plastic hinge pier segment (pier bottom segment) is drilled according to the position of the extended anchoring steel bars. During the factory prefabrication stage, it can provide accurate positioning for the extended anchoring steel bars at the pier bottom. It is not easy to deviate during the manufacturing process, and effectively ensures accurate alignment with the pre-embedded metal corrugated pipe of the pier cap during on-site assembly.

[0128] 8. The outer steel plate of the precast pier segment can protect and dampen the pier when they collide, reduce plastic damage to the concrete at the joints between different segments, enhance the restraint on the plastic hinge segments of the pier, and, combined with post-tensioned prestressed connection, effectively control the residual displacement of the precast segment pier after strong earthquake, ensure the self-resetting ability of the precast segment pier, and improve the overall seismic performance and energy dissipation capacity of the precast segment pier.

[0129] 9. High-performance materials and novel connection devices are applied to segmental piers, and the advantages of different pier connection structures are combined to form a hybrid seismic-resistant system, thereby improving the seismic performance of segmental piers. This initially achieves the goal of controllable earthquake damage and rapid post-earthquake repair for segmental piers, effectively improving the seismic safety of segmental piers. From the perspective of the entire life cycle of bridges, this new structural system has high practical engineering application value and superior economic benefits.

[0130] It is obvious that the above description and account are merely illustrative and not intended to limit the disclosure, application, or use of this invention. Although embodiments have been described and illustrated in the accompanying drawings, the invention is not limited to the specific examples exemplified by the drawings and described in the embodiments as currently considered the best mode for carrying out the teachings of the invention. The scope of the invention will include any embodiments falling within the foregoing description and the appended claims.

Claims

1. A steel-casing prefabricated rail transit bridge pier using a hybrid connection, comprising a pier cap and multiple pier segments supported on the pier cap, characterized in that: The multiple pier segments include a variable cross-section pier segment connected from top to bottom to form a complete pier, at least one straight pier segment, and a plastic hinge pier segment. The top of the pier is provided with multiple support pads, and the bottom of the pier is connected to the abutment. The pier segments are connected by a high-strength bolt flange structure. The bottom of the pier and the abutment are connected by a grouting corrugated pipe and an energy-dissipating steel flange structure. The pier and the abutment are connected by post-tensioned prestressing, thereby providing the pier with self-resetting capability. Each pier segment is encased in a steel sleeve, and an extended flange is installed at the connection point of the steel sleeve. Each pier segment and abutment is equipped with prestressed ducts for the prestressing tendons to pass through; The plastic hinge pier segment at the bottom of the pier body is connected to the pier cap. The pier cap has multiple energy-dissipating steel bars around the flange of the steel sleeve corresponding to the plastic hinge pier segment. The multiple energy-dissipating steel bars pass through the flange and are fixed by fastening nut assembly. The pier cap has multiple embedded metal corrugated pipes inside the energy-dissipating steel bars. The bottom of the plastic hinge pier segment has multiple anchoring steel bars that can extend into the embedded metal corrugated pipes. The steel sleeve connecting ends of the pier segments are equipped with multiple grouting conduits. One end of each grouting conduit is flush with the side of the steel sleeve, and the other end is flush with the surface of the precast concrete inside the pier segment. The grouting conduits are L-shaped with a rounded transition in the middle. The grouting conduit above the segment connection joint extends from the side of the steel sleeve to form a grout outlet, while the grouting conduit below extends from the side of the steel sleeve to form a grouting hole. After the flange connection is completed, grouting is performed on the connection joints between the pier segments using a grouting machine. The outlet grouting hole is formed by injecting micro-expansion cement mortar into the grouting channel through the grouting pipe pre-embedded at the top of the lower pier segment. After filling the reserved space in the segment connection joint, the excess micro-expansion cement mortar will flow out from the grouting hole through the grouting outlet channel formed by the grouting pipe pre-embedded at the bottom of the upper pier segment. Then, the grouting outlet is sealed, pressure is maintained, and the grouting hole is sealed again to complete the grouting operation of the segment connection joint. This ensures that the two connecting surfaces at the joint of the pier segment are completely fitted together, thereby ensuring the uniformity of force transmission in the pier.

2. The steel sleeve prefabricated rail transit bridge pier with hybrid connection as described in claim 1, characterized in that: A high-strength mortar cushion layer is provided between the pier body and the foundation.

3. The steel sleeve prefabricated rail transit bridge pier with hybrid connection as described in claim 1, characterized in that: The flanges of the steel sleeves between the pier segments are connected using high-strength bolt connection assemblies. Multiple connection holes are provided at intervals around the periphery of the two flanges for the high-strength bolt connection assemblies to pass through and connect.

4. The steel sleeve prefabricated rail transit bridge pier with hybrid connection as described in claim 1, characterized in that: The middle section of the pier segment is pre-embedded with a corrugated metal pipe, which forms a prestressed reserved duct in the middle of the pier segment after prefabrication.

5. A construction method for a steel sleeve prefabricated rail transit bridge pier using hybrid connection as described in any one of claims 1-4, characterized in that... The construction steps include the following: Step 1: Complete the factory prefabrication of the foundation and multiple pier segments; Step 2: Assemble the bottom pier segment with the foundation. First, match and assemble the segments, and lay grout-blocking templates around the joints. Then, level the adjusting pads placed at the joints and lay a high-strength mortar cushion layer. Next, hoist the bottom pier segment and connect it to the foundation through a grouting corrugated metal pipe. One end of the prestressing tendon is anchored to the bottom of the foundation, and the other end passes through the foundation and the bottom pier segment through a reserved hole, connecting the two together to complete the assembly of the bottom pier and the foundation. Step 3: Proceed to the next pier segment assembly. Hoist the next pier segment to the designated height and then slowly lower it to the designated position. Measure, control, and adjust its verticality and elevation to meet accuracy requirements. Install the connecting bolt assembly. During the prefabrication of the pier segment, a 20mm gap is left between the top surface of the internal concrete and the top surface of the flange. Grouting and discharge channels are reserved at the top and bottom of the pier segment, respectively. The corresponding grouting and discharge channels are located on the top and bottom sides of the pier segment. After the flange connection is completed, grout the joints between the pier segments to ensure complete contact between the two connecting surfaces at the joint, thereby ensuring the uniformity of force transmission in the pier. The prestressing tendons are connected to the previously assembled portion along the reserved channels in the center of the pier segment, completing the assembly of the second pier segment. Following the above assembly process, install the remaining straight pier segments and variable cross-section pier segments in sequence. Step 4: After the assembly is completed, use anchorages to anchor and tension the prestressed tendons in the pre-reserved anchorage grooves on the top surface of the variable cross-section pier segment to form a post-tensioned prestressed connection. Then, fill the anchorage grooves with cement mortar to complete the on-site assembly of the pier. Step 5: Complete the flange connection of the energy-dissipating steel bars between the bottom of the pier and the abutment. Drill and clean the abutment at the flange connection hole of the bottom pier segment, then inject adhesive into the hole to carry out the rebar installation operation, insert the energy-dissipating steel bars, install the nut connection assembly on the top of the energy-dissipating steel bars and tighten it to the specified torque to complete the flange connection of the energy-dissipating steel bars between the bottom of the pier and the abutment.

6. The construction method for prefabricated rail transit bridge piers using hybrid connections as described in claim 5, characterized in that: The prefabrication of each pier segment in step 1 includes the following sub-steps: Step 1.1: Cutting and processing of reinforcing bars and steel plates; Step 1.2: Weld the steel sleeves of the pier segments, weld the processed steel sleeves into a whole, and weld flanges at the connection ends of the steel sleeves. For the steel sleeves of the variable cross-section pier segments, only the lower end needs to be welded with flanges, and the others are welded at both ends. Step 1.3: Tie the reinforcing cage and lay the prestressed ducts; Step 1.4: Formwork erection. The corresponding segment steel sleeve is directly used as the steel formwork for the pier body. After the formwork is erected, the verticality of the pier needs to be adjusted again, and stiffening steel supports are used to support the steel formwork on the outside to ensure that the pier body formwork does not deform, tilt or rotate during the pouring and curing process, and remains perpendicular to the horizontal plane. Step 1.5: Hoist the reinforcing steel cage and hoist the tied reinforcing steel cage into the steel sleeve formwork; Step 1.6: Concrete pouring and component curing.

7. The construction method for prefabricated rail transit bridge piers using hybrid connections as described in claim 5, characterized in that: The prefabrication of the foundation in step 1 includes the following sub-steps: Step 1.1: Steel bar cutting and processing; Step 1.2: Tie the reinforcing cage and lay the prestressed ducts; Step 1.3: Formwork erection. The foundation should be square in size. The formwork should be made of wood and reinforced with tie rods after installation. Step 1.4: Hoist the steel reinforcement cage and hoist the tied steel reinforcement cage into the erected formwork; Step 1.5: Concrete pouring and component curing; Step 1.6: Demolding and curing of components.

8. The construction method for prefabricated rail transit bridge piers using hybrid connections as described in claim 5, characterized in that: Step 3 includes: assembling the next pier segment. First, the prestressing ducts should be sealed with expansion sealant strips on the top surface of the concrete of the previous pier segment to prevent grout from seeping into the prestressing ducts during subsequent grouting. The connecting surfaces of the upper and lower pier segments should be cleaned. The level of the top flange of the previous pier segment should be measured and the gaskets adjusted. The next pier segment should be hoisted to the designated position, and its verticality and elevation should be measured, controlled, and adjusted. After meeting the accuracy requirements, the connecting bolt assembly should be installed, and all high-strength connecting bolts should be tightened to the specified torque according to the design standards. The pier segment lifting equipment should be removed, and the guide ropes should be untied.

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