Anti-corrosion and fatigue-resistant prestressed steel strand system and construction method

Abstract

The present application relates to prestressed steel strand technical field, specifically disclose a corrosion-resistant and fatigue-resistant prestressed steel strand system and construction method, including the following modules: steel structure support unit is provided with layered anchoring position, multilayer prestressed steel strand cable net includes main load-bearing steel strand, stable steel strand and cable-stayed wind-resistant steel strand, each steel strand has surface anticorrosive layer, anticorrosive filling medium and weather resistant sheath, steel strand end connection sealing anticorrosion composite anchor, cable force dynamic compensation limiting node is provided with buffer hoop and elastic compensation component, synchronous tension positioning tool is provided with two end tensioning actuator, cable force sensor and laser ranging device.The present application is limited by corrosion medium by multilayer protection and sealing anchoring, and different direction load is shared by layered cable net, and the sliding buffer compensation structure is matched with the tension detection structure, so that the steel strand tension is found, the cable force change compensation and the two end cable force and the span middle reverse arch detection are coordinated.

Description

Technical Field

[0001] This invention relates to the field of prestressed steel strand technology, and in particular to a corrosion-resistant and fatigue-resistant prestressed steel strand system and construction method. Background Technology

[0002] The field of prestressed steel strand technology mainly involves steel strands formed by twisting multiple high-strength steel wires and their tensioning, anchoring, protection, and construction treatment in concrete structures, bridge structures, and other engineering projects. It typically involves the coordinated use of steel strands, anchorages, wedges, corrugated pipes, grouting materials, and tensioning equipment, with the installation, tensioning, locking, and protection completed according to the designed tension force, elongation, anchoring position, and construction sequence. Among these, the traditional anti-corrosion and fatigue-resistant prestressed steel strand system and construction method refers to the anti-corrosion treatment and cyclic stress control of prestressed steel strands during installation, tensioning, anchoring, and service. This usually involves applying a coating, sheath, or filling protective material to the surface of the steel strand, threading the steel strand through pre-reserved ducts and connecting it to the anchorages, applying prestress using jacks according to the set tensioning program, verifying the tension force and elongation, and sealing or grouting the ducts, anchoring ends, and exposed steel strands after anchoring.

[0003] When traditional prestressed steel strands bear load-bearing stability and wind resistance in long-span flexible supports, the high humidity, high salt spray, and ammonia nitrogen environment of fish ponds cause the protective layer on the surface of the steel wires and the anchor ends to be subjected to corrosive media for a long time. Under wind vibration and alternating loads, the cable body will repeatedly experience stress concentration at the clamping position. Single-sided tensioning will also cause differences in the stress distribution of steel strands across multiple spans. The anchor ends are prone to corrosion and slippage after being invaded by water vapor. The single anchoring position of the steel structure makes it difficult to coordinate the cables with different stress directions, which will lead to repeated correction and maintenance after the cable force decays. Summary of the Invention

[0004] The purpose of this invention is to provide a corrosion-resistant and fatigue-resistant prestressed steel strand system and construction method. Through the coordinated configuration of the corrosion-resistant and fatigue-resistant steel strand structure and the synchronous tensioning positioning fixture, and combined with the synchronous detection and graded adjustment of the tension force at both ends and the mid-span arching state during the tensioning process, the steel strand forms a prestressed state according to the predetermined tensioning process on the basis of corrosion protection. This reduces the stress deviation caused by asynchronous tensioning at both ends, and coordinates and controls the stress state and mid-span deformation state of the steel strand during the tensioning process to meet the comprehensive requirements of corrosion protection, fatigue stress and tension control during the construction of prestressed steel strands.

[0005] To achieve the above objectives, the present invention provides a corrosion-resistant and fatigue-resistant prestressed steel strand system, including steel strands and a corrosion-resistant and fatigue-resistant structure and a synchronous tensioning and positioning fixture that are configured in conjunction with the steel strands. The corrosion-resistant and fatigue-resistant structure provides protection for the steel strands, and the synchronous tensioning and positioning fixture performs synchronous tensioning at both ends of the steel strands and detects the tensioning status, so that the corrosion-resistant and fatigue-resistant structure and the prestressing process work together on the steel strands. The synchronous tensioning positioning fixture includes a tensioning actuator for applying tensioning loads to both ends of the steel strand, a cable force sensor for collecting the tension force at both ends of the steel strand, and a laser ranging device for collecting the mid-span anti-arch state of the steel strand. During the tensioning process, the tensioning load applied to both ends of the steel strand by the tensioning actuator is coordinated and adjusted based on the comparison results of the tensioning forces at both ends collected by the cable force sensor and the mid-span anti-arch state collected by the laser ranging device, so that the tensioning process at both ends of the steel strand corresponds to the mid-span deformation state.

[0006] Furthermore, the synchronous tensioning positioning fixture includes a double-jack synchronous tensioning base symmetrically arranged at both ends of the steel strand. The tensioning actuator consists of jacks respectively installed on the double-jack synchronous tensioning base and acting on both ends of the steel strand. The cable force sensor collects the tension force at both ends of the steel strand, and the laser rangefinder collects the anti-arching state at the mid-span of the steel strand. The double-jack synchronous tensioning base adjusts the tension load of the corresponding jacks according to the comparison results of the tension forces at both ends and the anti-arching state at the mid-span, thereby establishing a coordinated adjustment relationship between the tension load at both ends and the anti-arching state at the mid-span.

[0007] Furthermore, the dual-jack synchronous tensioning base is configured to control the jacks at both ends to sequentially perform initial tensioning, secondary tensioning, and final tensioning at 30%, 65%, and 100% of the design prestress, with each tensioning stage held and stabilized for 10 minutes. During each tensioning stage, the cable force sensor synchronously collects the tension force at both ends of the steel strand and compares the tension forces at both ends. When the difference in tension force between the two ends is no greater than 3%, the next tensioning stage begins. When the difference in tension force between the two ends is greater than 3%, the tensioning load of the jacks is adjusted accordingly, and the tension forces at both ends of the steel strand are re-compared after adjustment. Simultaneously, the tensioning load at both ends is adjusted based on the mid-span anti-arching state collected by the laser ranging device, thus forming a continuous tensioning control process of staged tensioning, comparison of tension forces at both ends, and detection of mid-span anti-arching state.

[0008] Corresponding to the anti-corrosion and fatigue-resistant prestressed steel strand system, the present invention also provides a construction method. The construction method takes the steel strand, the anti-corrosion and fatigue-resistant structure, and the synchronous tensioning and positioning fixture as the construction objects and execution basis. After the steel strand completes the corresponding anti-corrosion and fatigue-resistant structure configuration, the tensioning load is applied from both ends of the steel strand through the tensioning execution mechanism, and the tension force at both ends of the steel strand is synchronously obtained by the cable force sensor. The anti-arch state of the steel strand at the mid-span is obtained by the laser ranging device. During the tensioning process, tension loads are applied progressively according to predetermined tensioning levels. At each tensioning level, the corresponding tension state is maintained, and the tension forces at both ends are acquired and compared. When the tension forces at both ends meet the set synchronization conditions, the tensioning control for the current level is completed, and the process proceeds to the next tensioning level. When the tension forces at both ends do not meet the set synchronization conditions, the tension load at the corresponding ends is adjusted via the tensioning actuator. After adjustment, the tension forces at both ends are acquired and compared again. During the tension force adjustment process, the tension load at both ends is simultaneously adjusted based on the mid-span anti-arching state acquired by the laser ranging device, so that the tension force control result and the mid-span anti-arching state of the steel strand serve as the control basis for the tensioning process.

[0009] Preferably, the construction method uses 30%, 65%, and 100% of the design prestress as the initial tensioning, secondary tensioning, and final tensioning levels, respectively. Each tensioning level is held and stabilized for 10 minutes, and the tension forces at both ends are collected synchronously during each tensioning level. When the difference in tension forces at both ends is no greater than 3%, the next tensioning level is entered. When the difference in tension forces at both ends is greater than 3%, the tensioning load at the corresponding end is adjusted and the tension forces are compared again. At the same time, the tensioning load at both ends is coordinated and adjusted according to the anti-arch state at mid-span until the control process of the corresponding tensioning level is completed. Therefore, the corrosion-resistant and fatigue-resistant prestressed steel strand system and construction method form a technical solution that integrates the corrosion-resistant and fatigue-resistant structure of the steel strand, the tensioning execution at both ends, the synchronous acquisition of tension force, the acquisition of the mid-span anti-arch state, and the coordinated adjustment of tension load. This ensures that the protective structure of the steel strand and the prestressed construction control are kept in a unified system, and provides a basis for the detection and adjustment of the stress state at both ends and the deformation state at the mid-span during the graded tensioning process.

[0010] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, the anti-corrosion layer on the steel wire surface, the anti-corrosion filling medium in the stranding gap, and the weather-resistant sheath form a continuous protective path from the steel wire surface to the outer periphery of the cable body. The sealed anti-corrosion composite anchor provides closed protection for the ends of the steel strands, reducing the entry of corrosive media into the cable body and anchorage positions. The main load-bearing steel strands, stabilizing steel strands, and inclined wind-resistant steel strands are respectively connected to the layered anchorage positions, allowing loads in different directions to be transmitted through the corresponding cable bodies. The buffer clamp allows the steel strands to slide axially and works with the elastic compensation component to respond to changes in cable length and cable force. The synchronous tensioning positioning fixture, through the cooperation of tensioning actuators at both ends, cable force sensors, and laser ranging devices, provides a detection and execution basis for the consistency of cable force and the control of the mid-span anti-arch state during graded tensioning. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A schematic diagram of the overall structure of the corrosion-resistant and fatigue-resistant prestressed steel strand system; Figure 2 This is a schematic diagram of the anti-corrosion and fatigue-resistant hierarchical structure of prestressed steel strands; Figure 3 Schematic diagram of a sealing and corrosion-resistant composite anchor and a dynamic compensation limit node for cable force; Figure 4 A schematic diagram illustrating the synchronous tensioning positioning fixture and the tensioning detection feedback relationship; Figure 5 A schematic diagram of the construction process for a corrosion-resistant and fatigue-resistant prestressed steel strand system. Detailed Implementation

[0013] To facilitate understanding of the structural composition, assembly relationship, stress path, and construction control process of this invention, the following description, in conjunction with the accompanying drawings, illustrates the corrosion-resistant and fatigue-resistant prestressed steel strand system and construction method. The steel structure support unit referred to below is a physical support structure used to support a multi-layer prestressed steel strand network and form layered anchorage positions; the multi-layer prestressed steel strand network includes main load-bearing steel strands, stabilizing steel strands, and inclined wind-resistant steel strands; the dynamic cable force compensation limiting node refers to a node structure that provides radial constraint on the steel strand when it passes through an intermediate support position, allows the steel strand to slide axially during the tensioning stage, and provides elastic compensation when the stress state changes; the synchronous tensioning positioning fixture refers to a construction fixture that applies tension loads to both ends of the steel strand and simultaneously obtains the tension force at both ends and the mid-span anti-arch state. The tension at both ends is used to determine the consistency of the loading state on both sides, and the mid-span anti-arch state is used to characterize the geometric change of the mid-span position of the steel strand during tensioning. The two detection quantities correspond to the stress state and the linear state, respectively, and jointly participate in the adjustment of the tension load.

[0014] Example 1 Please see Figure 1-4 This embodiment provides a corrosion-resistant and fatigue-resistant prestressed steel strand system, which includes a steel structure support unit, a multi-layer prestressed steel strand network, sealed and corrosion-resistant composite anchors, dynamic force compensation limiting nodes, and synchronous tensioning positioning fixtures. The steel structure support unit provides support and anchorage positions for the cable network. The multi-layer prestressed steel strand network forms force transmission paths in different directions. The sealed and corrosion-resistant composite anchors are located at the ends of the steel strands. The dynamic force compensation limiting nodes are located at the positions where the steel strands pass through intermediate supports. The synchronous tensioning positioning fixtures act on both ends of the steel strands and obtain the tension force at both ends and the mid-span anti-camber state during the tensioning process.

[0015] Please see Figure 1 The steel structure support unit includes steel end columns located at the ends of the pond embankment, steel middle columns spaced apart within the pond, and underwater PHC pipe pile foundations supporting the end and middle columns. The underwater PHC pipe pile foundations bear the vertical and horizontal loads transmitted by the end and middle columns. The end columns form the anchorage boundaries at the ends of the spans, while the middle columns provide intermediate support along the span's extension direction. Layered anchorage beams are installed at the top of both the end and middle columns. These beams, along their height, form the main cable anchorage positions, stabilizing cable limiting positions, and wind-resistant cable connection positions, ensuring that the three types of steel strands are connected to their respective positions, rather than being concentrated and stacked at the same anchorage location.

[0016] In this embodiment, the steel structure end columns and steel structure middle columns adopt a steel structure form, with layered anchored steel beams fixedly connected to the top of the corresponding columns. For the fishpond surface construction scenario, the steel structure end columns and steel structure middle columns can be made of Q355B welded H-beams with zinc-aluminum-magnesium protection, with anti-corrosion steel anchor plates installed at the bottom of the columns corresponding to the underwater foundation positions, and underwater anti-corrosion clamps used at the underwater connection positions. The steel structure materials and surface protection forms are used to form the supporting foundation of the steel strand network, without changing the layered relationship between the main cable anchorage positions, the stabilizing cable limiting positions, and the wind-resistant cable connection positions.

[0017] The main load-bearing steel strands are continuously arranged along the main span direction and connect to the main cable anchorage positions. These strands serve as the cable body to bear the photovoltaic modules and corresponding vertical loads. The stabilizing steel strands are arranged roughly along the same span direction as the main load-bearing steel strands and connect to the stabilizing cable restraint positions. The stabilizing steel strands and main load-bearing steel strands are layered in the height direction. The inclined wind-resistant steel strands connect the wind-resistant inclined cable connection positions of the steel structure end columns and middle columns, forming an oblique force transmission path relative to the main load-bearing and stabilizing steel strands. Thus, vertical loads are transmitted to the steel structure support units through the main load-bearing and stabilizing steel strands, while horizontal wind loads are transmitted to the corresponding end and middle columns along the inclined wind-resistant steel strands.

[0018] The main cable anchorage is located at the top of the layered anchored steel beams and mates with the ends or corresponding support positions of the main load-bearing steel strands. The stabilizing cable limiting positions are layered along the height direction with the main cable anchorage positions, limiting the stabilizing steel strands. The wind-resistant cable connection positions are located on the sides of the layered anchored steel beams and connect with the wind-resistant cable strands. The main load-bearing steel strands and stabilizing steel strands extend along the span direction, and the wind-resistant cable strands form an oblique connection between the steel structure end columns and the steel structure middle columns. The layered force relationship is established by the spatial positions of the three types of cables and their corresponding connection positions.

[0019] Please see Figure 2 In multi-layer prestressed steel strand networks, the main load-bearing steel strands, stabilizing steel strands, and inclined wind-resistant steel strands can all adopt a 7-wire prestressed structure. The steel strand consists of a central steel wire and outer layers of steel wires twisted around it. Each individual steel wire has a zinc-aluminum-magnesium-rare-earth alloy composite coating on its outer surface. The gaps formed after the wires are twisted are filled with neutral anti-corrosion lubricating grease. After twisting and gap filling, the outer periphery of the steel strand is continuously covered with a high-density polyethylene weather-resistant sheath. The composite coating on the steel wire surface, the neutral anti-corrosion lubricating grease between the wires, and the high-density polyethylene weather-resistant sheath around the entire steel strand constitute a layered protection path from the surface of each individual steel wire, through the twisted interior, to the outer periphery of the cable.

[0020] In this embodiment, the nominal diameter of the steel strand can be 15.2 mm, the tensile strength of the steel strand can be 1900 MPa, the total thickness of the zinc-aluminum-magnesium rare earth alloy composite coating is not less than 85 μm, and it contains lanthanum and cerium as coating modification components. The above values ​​are used to describe an executable steel strand configuration. A micro-arc transition stranding structure is adopted at the stranding contact transition position of the steel wires, so that adjacent steel wires still form a gap for accommodating neutral anti-corrosion lubricant after stranding, and avoids the formation of abrupt contact boundaries at the steel wire cross-section transition position. A high-density polyethylene weather-resistant sheath is located at the outermost periphery of the stranded steel strand, covering the already formed steel wire strand and neutral anti-corrosion lubricant inside the sheath.

[0021] During the fabrication and installation of steel strands, neutral anti-corrosion grease is filled into the stranding gaps between adjacent steel wires. The grease is distributed throughout the internal gaps as the wires are twisted, and is not intended to replace the mechanical twisting contact between the wires. A high-density polyethylene weather-resistant sheath is continuously installed along the length of the steel strand. At locations where connection to a sealed, anti-corrosion composite anchor is required, the ends of the steel strand are treated to the length needed for anchoring, allowing the steel strand to enter the corresponding anchor and achieve axial anchoring.

[0022] Please see Figure 3 Tensioning end anchors are installed at both ends of the steel strand. After the steel strand passes through the corresponding anchor, the anchor applies axial constraint to the steel strand, so that the tension established during the tensioning process can be transmitted to the steel structure support unit.

[0023] Both the tensioning end anchor and the fixed end compression anchor have double-layer rubber O-rings installed at the inlet and outlet of the steel strand. These double-layer rubber O-rings are arranged around the outer circumference of the steel strand and positioned at the boundary where the steel strand enters the corresponding anchor. The portion of the steel strand extending beyond the anchor is covered with a heat-shrinkable sealing sleeve, the inside of which is filled with epoxy anti-corrosion paste, placing the epoxy anti-corrosion paste between the end of the steel strand and the corresponding anchor. When the steel strand enters the anchor from the outside, it passes through the inlet and outlet sealing area formed by the double-layer rubber O-rings and the external covering area formed by the heat-shrinkable sealing sleeve. The epoxy anti-corrosion paste fills the end gaps, thus creating a continuous closed path between the outer circumference of the steel strand end and the anchor inlet and outlet.

[0024] During the assembly of the sealed and corrosion-resistant composite anchor, the end of the steel strand is first inserted into the corresponding anchor to complete the anchoring fit. Then, a double-layer rubber O-ring is placed around the steel strand to form a sealed contact. Subsequently, epoxy anti-corrosion paste is filled into the space corresponding to the end of the steel strand and the heat-shrinkable sealing sleeve, and the heat-shrinkable sealing sleeve covers the protruding part of the steel strand. This assembly sequence ensures that the end anchoring and end protection have clearly defined positions, while preventing the heat-shrinkable sealing sleeve from obstructing the steel strand from completing the anchoring fit first.

[0025] Continue reading Figure 3The dynamic cable force compensation limiting node is set at the layered anchorage position corresponding to the central column of the steel structure. The dynamic cable force compensation limiting node includes a buffer clamp and an elastic compensation component. The buffer clamp is sleeved on the outer periphery of the corresponding steel strand, and a polyurethane buffer bushing is set on the inner side of the buffer clamp, which directly faces the outer periphery of the steel strand. During the tensioning and shaping stage of the steel strand, the buffer clamp provides radial restraint to the steel strand, restricting the steel strand from leaving the predetermined support position, while retaining the degree of freedom for the steel strand to slide relative to its own axis.

[0026] The permissible movement of the buffer clamp is limited to displacement of the steel strand relative to the buffer clamp along the strand's axis. Displacement of the steel strand perpendicular to the axis is constrained by both the buffer clamp and the polyurethane buffer bushing. Therefore, during tensioning, the steel strand can redistribute the tension displacement between adjacent support positions through axial sliding, without being blocked from the transmission of tension displacement along the cable length due to premature rigid locking at intermediate positions. After tensioning is completed and the corresponding locking is achieved, the buffer clamp continues to maintain the radial constraint relationship of the steel strand.

[0027] An elastic compensation component is positioned between the buffer clamp and the steel structure support unit. In this embodiment, a disc spring compensation component is used. The disc spring compensation component is assembled in a predetermined compression state, causing elastic deformation when the buffer clamp is subjected to axial force from the steel strand. When the steel strand undergoes axial displacement due to temperature changes, load fluctuations, or changes in stress state, the force is first transmitted to the buffer clamp. The buffer clamp, through its connection with the disc spring compensation component, causes a change in the compression of the disc spring compensation component. The elastic recovery effect generated by the disc spring compensation component is then fed back to the buffer clamp and the corresponding steel strand. The cable force dynamic compensation limiting node thus forms a mechanical action chain of axial state change of the steel strand, buffer clamp response, elastic deformation of the disc spring compensation component, and return of the compensation effect to the steel strand.

[0028] The specific pre-compression amount of the disc spring compensation assembly is adjusted after the system tensioning is completed, ensuring that the disc spring compensation assembly is in a working state with continued compression and recoverable stroke. The pre-compression amount is not set independently of the actual tensioning state of the steel strand, but is adjusted in conjunction with the state of the cable body after the steel strand reaches its final tension and the anchorage is locked. After adjustment, the working state of the node can be confirmed by re-measuring the steel strand tension and observing whether the buffer clamp and disc spring compensation assembly are in the predetermined assembly position.

[0029] Please see Figure 4The synchronous tensioning positioning fixture includes a double-jack synchronous tensioning base symmetrically arranged at both ends of the steel strand, cable force sensors respectively arranged at both ends of the steel strand for obtaining tension force, and a laser ranging device for obtaining the mid-span anti-arch state. The tensioning actuator uses jacks respectively installed on the double-jack synchronous tensioning base, with the two jacks acting on the two ends of the same steel strand to be tensioned, so that both ends of the steel strand can receive controlled tension loads.

[0030] The tension sensors are positioned to reflect the tension force at the corresponding ends, generating first and second end tension forces respectively. These two tension forces are synchronously measured within the same tensioning level, used to directly compare the stress states at the two ends of the same steel strand. A laser ranging device is positioned at the mid-span of the steel strand, using the change in distance between the mid-span position and the construction reference during tensioning as the basis for detecting the mid-span camber state. The laser ranging device maintains the same measurement position and geometric reference at each tensioning level, ensuring that distance changes at different tensioning stages correspond to linear changes at the same mid-span position.

[0031] The controlled object of the dual-jack synchronous tensioning base is the tension load of the jacks at both ends of the steel strand. After tensioning begins, the jacks at both ends apply loads simultaneously, and the cable force sensors synchronously acquire the tension forces at both ends. When there is a difference in the tension forces at both ends, the loading state of the end with the lower tension force and the end with the higher tension force are compared, and the difference in tension forces at both ends is reduced by adjusting the tension load of the corresponding jacks. The adjusted tension state is then acquired again by the two cable force sensors, thus forming a feedback process of tension load adjustment, cable force re-acquisition, and re-comparison of the tension forces at both ends.

[0032] The mid-span anti-camber state is obtained synchronously with the tension forces at both ends. The tension forces at both ends reflect the stress state at the ends, while the mid-span anti-camber state reflects the geometric state of the cable in the middle. Once the tension forces at both ends meet the synchronization conditions for the current tension level, the mid-span anti-camber state obtained by the laser ranging device is used to check the strand alignment, and the tension loads at both ends are adjusted according to the mid-span anti-camber state. The detection of the mid-span anti-camber state does not replace the comparison of the tension forces at both ends; both types of detection quantities participate in the same tensioning process, ensuring that tension control simultaneously has both stress detection paths and alignment detection paths.

[0033] In this embodiment, the tensioning process is divided into initial tensioning, secondary tensioning, and final tensioning, with the three tension levels being 30%, 65%, and 100% of the design prestress, respectively. Each tension level is held and stabilized for 10 minutes. After entering a tension level, the jacks at both ends are synchronously loaded to the corresponding tension state, and the two cable force sensors obtain the tension force at the corresponding ends. When the difference in tension force between the two ends is not greater than 3%, the synchronization condition at both ends for the current level is met, and the process proceeds to the next tension level after confirming the holding and stabilization of the load and the mid-span anti-arch state. When the difference in tension force between the two ends is greater than 3%, the synchronization condition at both ends for the current level is not met, and the process does not proceed to the next tension level. Instead, the tension load of the corresponding jacks is adjusted, and the tension forces at both ends are obtained again and compared.

[0034] During the recomparison of tension forces at both ends, the laser ranging device continues to acquire the mid-span anti-arch state. If the adjustment of the jack load causes a change in the mid-span anti-arch state, the tension loads at both ends will continue to be coordinated while maintaining the current tension level, ensuring that the stress state at both ends and the mid-span alignment state are both within the control process of the current tension level. Only after the current tension level reaches the corresponding control conditions will the next tension level be entered. The three tension levels form a progressive execution relationship, directly entering the final tension without skipping intermediate levels.

[0035] With the above structural configuration, the force path of the steel strand can be transferred from the steel strand body to the steel structure end column or the steel structure middle column through the sealed and corrosion-resistant composite anchor. At the intermediate support position, the steel strand is radially limited by the buffer clamp and disc spring compensation assembly and accepts the elastic response to changes in axial state. During the tensioning stage, prestress is established by jacks at both ends, and the stress state and mid-span alignment state are detected by cable force sensors and laser ranging devices, respectively. There are clear mechanical interactions and detection feedback boundaries between the various structures.

[0036] Example 2 Please see Figure 5 This embodiment provides a construction method for a corrosion-resistant and fatigue-resistant prestressed steel strand system. Compared with Embodiment 1, the difference in this embodiment lies in that it focuses on the construction sequence and tension control process. The structural relationships of the steel structure support unit, multi-layer prestressed steel strand network, sealed and corrosion-resistant composite anchor, dynamic compensation limit node for cable force, and synchronous tensioning positioning fixture are maintained in accordance with the aforementioned system. The construction process sequentially connects the steel strand installation state, axial slip state, graded tensioning state, anchoring and sealing state, elastic compensation state, and static retesting state.

[0037] S1. Install the steel structure support units. Set up underwater PHC pipe pile foundations according to the construction location, and install the steel structure end columns and middle columns at the corresponding foundation locations, ensuring the layered anchoring steel beams at the top of the end and middle columns are in their predetermined positions. The main cable anchorage positions, stabilizing cable limit positions, and wind-resistant cable connection positions on the layered anchoring steel beams are used for subsequent reception of the main load-bearing steel strands, stabilizing steel strands, and wind-resistant cable strands, respectively. After the steel structure installation is completed, the observable state is that each layered anchorage position can form a continuous support path along the corresponding cable arrangement direction.

[0038] S2, proceed with the cutting and pre-installation of steel strands at the ends. The cutting length of the steel strands is determined according to the construction span; in one construction configuration, the single span length can range from 30m to 80m. Tensioning end anchors are pre-installed at both ends of the steel strands. The main load-bearing steel strands, stabilizing steel strands, and wind-resistant cable-stayed steel strands are respectively delivered to the main cable anchorage position, the stabilizing cable limiting position, and the wind-resistant cable-stayed cable connection position, ensuring that different cable bodies correspond to their respective layer positions.

[0039] S3, temporary restraint of the steel strands. When the steel strands pass through the central column of the steel structure, they are pre-clamped by buffer clamps, with polyurethane buffer bushings positioned between the buffer clamps and the steel strands. This pre-clamping prevents the steel strands from radially disengaging relative to the layered anchored steel beams, while not locking them along the axial direction. Therefore, when tension loads are subsequently applied at both ends, the steel strands can slide axially relative to the buffer clamps to find their shape. Before formal tensioning, the inclined wind-resistant steel strands are connected to the corresponding wind-resistant inclined cable connection positions, ensuring the inclined cable body maintains the spatial position required for construction.

[0040] S4, Perform simultaneous graded tensioning at both ends. At the start of tensioning, the jacks at both ends act on the same steel strand, and the cable force sensors simultaneously acquire the tension force at both ends, while the laser rangefinder acquires the mid-span anti-arch state. In the initial tensioning stage, the tension state is established to 30% of the design prestress and held for 10 minutes. During this stage, the tension forces at both ends are continuously compared. When the difference in tension forces at both ends is not greater than 3%, the current stage meets the cable force conditions for entering the next tensioning stage. When the difference in tension forces at both ends is greater than 3%, the stage does not proceed to the next stage, but the tension load of the corresponding end jacks is adjusted, the tension forces at both ends are acquired again, and the comparison is repeated.

[0041] After the initial tensioning is completed, the secondary tensioning begins, increasing the tension to 65% of the design prestress and holding the load for 10 minutes. The secondary tensioning process continues with the same acquisition of tension forces at both ends, comparison of differences, and load correction, while simultaneously reading the mid-span arching status. Once the difference in tension forces at both ends meets the condition of not exceeding 3% and the current load holding process is completed, the final tensioning begins.

[0042] Final tensioning raises the tension to 100% of the design prestress and holds the load for 10 minutes. During final tensioning, simultaneous data acquisition from two cable force sensors and detection by a laser rangefinder continue. When the difference in tension force between the two ends exceeds 3%, the corresponding jacks continue to adjust the load, and the tension force at both ends is reacquired after each adjustment. When the difference in tension force between the two ends is not greater than 3%, the current final tensioning state is maintained, and final tensioning control is completed in conjunction with the mid-span anti-arch state. The three levels progress in the order of 30%, 65%, and 100%, and the next level is not entered before the synchronization conditions of the previous level are met.

[0043] The mid-span anti-camber state participates in the tension load adjustment at every tensioning stage. A laser rangefinder continuously acquires distance data at the same mid-span detection location; the mid-span anti-camber state at the current tensioning level is reflected in the current measurement results. After synchronously or correspondingly adjusting the tension loads at both ends based on changes in the mid-span anti-camber state, the tension force at both ends is obtained by the cable force sensor, avoiding the need to continue executing subsequent stages solely based on the pre-adjustment tension force. Therefore, any load adjustment involves a closed-loop process of pre-adjustment detection, adjustment execution, and post-adjustment re-detection.

[0044] S5. Anchor locking and end sealing are performed. After final tensioning and load holding, the clamping structure corresponding to the tensioning end anchor is locked, transferring the tensioning state from the jack to the anchor. After anchor locking, the ends of the steel strands are treated by filling the ends of the steel strands and the corresponding areas of the anchors with epoxy anti-corrosion paste, and ensuring that the double-layer rubber O-rings are kept in the sealed position at the inlet and outlet of the steel strands. Then, the protruding parts of the steel strands are covered with heat-shrinkable sealing sleeves. The completed state is characterized by the steel strand ends being axially locked by the anchors, and a continuous end seal formed by the double-layer rubber O-rings, epoxy anti-corrosion paste, and heat-shrinkable sealing sleeves.

[0045] S6. Adjust the disc spring compensation assembly. After the anchor is locked, adjust the pre-compression state of the disc spring compensation assembly corresponding to the position of the steel structure's central column to maintain the predetermined elastic working stroke of the disc spring compensation assembly under the current tension of the steel strand. During the adjustment process, the buffer clamp continues to radially limit the steel strand, and the disc spring compensation assembly establishes a mechanical relationship with the steel strand through the buffer clamp. After the adjustment is completed, when the axial state of the steel strand changes, the buffer clamp will transmit its action to the disc spring compensation assembly, and the elastic deformation of the disc spring compensation assembly will then act on the buffer clamp, thus forming a mechanical compensation path.

[0046] After adjusting the dynamic compensation limit nodes for cable tension, install the corresponding photovoltaic module clamps and photovoltaic arrays along the main load-bearing steel strands. The vertical force generated by the photovoltaic modules is first transmitted to the main load-bearing steel strands, and then from the main load-bearing steel strands to the layered anchored steel beams and steel structure support units; the stabilizing steel strands are arranged in layers with the main load-bearing steel strands, and the inclined wind-resistant steel strands maintain the oblique connection between the steel structure end columns and the steel structure middle columns.

[0047] S7. Perform static retesting and protective inspection. After the steel strand has completed final tensioning, anchoring, and adjustment of the disc spring compensation assembly, allow it to stand for 72 hours, and then obtain the steel strand tension again. Compare the retested tension with the corresponding tension at the time of tensioning. If the tension deviation exceeds 5%, fine-tune the disc spring compensation assembly, and reconfirm the steel strand tension status after adjustment; if the tension deviation does not exceed 5%, maintain the current compensation status. After the retesting, check the sealing positions of the outer weathering sheath of the steel strand and the corresponding sealing positions of the sealed anti-corrosion composite anchor, and confirm the continuity of the sheath and end sealing structure.

[0048] During the aforementioned construction process, the installation status of the steel strands is determined by the layered anchorage positions; the axial degree of freedom during tensioning is limited by buffer clamps; the tension load is applied by jacks at both ends; the stress state at both ends is obtained by cable force sensors; the mid-span geometry is obtained by a laser rangefinder; axial locking after tensioning is achieved by sealed and corrosion-resistant composite anchorages; the mechanical response corresponding to changes in stress state is handled by disc spring compensation components; and the cable force state after settling is confirmed through a re-measurement process. The input state for each stage is generated from the previous stage, and the subsequent stage does not invoke construction states that have not yet been generated.

[0049] This invention specifically describes the structure, assembly relationships, construction sequence, tension levels, judgment conditions, testing methods, and component combinations to illustrate the feasible forms of corrosion-resistant and fatigue-resistant prestressed steel strand systems and construction methods. Without departing from the technical solutions described in this invention and the application documents, those skilled in the art can make equivalent substitutions, modifications, or combinations of the corresponding structural connection forms, component forms with the same working mechanism, and construction sequences without changing the preceding and following technical relationships. Equivalent changes should maintain the correspondence between the steel structure support units and the layered cable net, the steel strand protection levels, the relationship between sliding limits and elastic compensation, the testing relationship between the tension forces at both ends and the mid-span anti-arch state, and the feedback relationship of graded tensioning. The substantive correspondence between the technical objects should not be altered due to changes in name or representation.

Claims

1. A corrosion-resistant and fatigue-resistant prestressed steel strand system, characterized in that, This includes steel structure support units, multi-layer prestressed steel strand network, sealed and anti-corrosion composite anchors, dynamic cable force compensation limiting nodes, and synchronous tensioning positioning fixtures. The steel structure support unit has layered anchorage positions, and the multi-layered prestressed steel strand network includes main load-bearing steel strands, stabilizing steel strands and inclined wind-resistant steel strands that are respectively connected to the corresponding layered anchorage positions. Each steel strand includes an anti-corrosion layer on the surface of the steel wire, an anti-corrosion filling medium for the stranding gap, and a weather-resistant sheath covering the outer periphery of the steel strand. The ends of the steel strands are connected to the steel structure support unit through sealed anti-corrosion composite anchors. The cable force dynamic compensation limiting node includes a buffer clamp that allows the steel strand to slide axially and an elastic compensation component set between the buffer clamp and the steel structure support unit; The synchronous tensioning positioning fixture includes tensioning actuators acting on both ends of the steel strand, cable force sensors that detect the cable force at both ends, and a laser ranging device that detects the anti-arch state at the mid-span.

2. The anti-corrosion and fatigue-resistant prestressed steel strand system according to claim 1, characterized in that, The steel structure support unit includes steel structure end columns set at the end of the pond embankment, steel structure middle columns spaced apart in the pond, and underwater PHC pipe pile foundations supporting the steel structure end columns and steel structure middle columns. Layered anchoring steel beams are set at the top of both the steel structure end columns and the steel structure middle columns. The layered anchored steel beams form independent main cable anchorage positions, stabilizing cable limiting positions, and wind-resistant cable connection positions along the height direction. The main load-bearing steel strands connect to the main cable anchorage positions, the stabilizing steel strands connect to the stabilizing cable limiting positions, and the wind-resistant cable strands connect to the wind-resistant cable connection positions.

3. The corrosion-resistant and fatigue-resistant prestressed steel strand system according to claim 2, characterized in that, The main cable anchorage position is located at the upper part of the layered anchorage steel beam and anchors the end of the main load-bearing steel strand. The stabilizing cable limiting position is set in layers along the height direction with the main cable anchorage position and limits the stabilizing steel strand. The wind-resistant cable connection position is set on the side of the layered anchorage steel beam and connected to the wind-resistant cable, so that the main load-bearing steel strand and the stabilizing steel strand are arranged along the span direction. The wind-resistant cable forms an oblique connection between the steel structure end column and the steel structure middle column.

4. The anti-corrosion and fatigue-resistant prestressed steel strand system according to claim 3, characterized in that, The main load-bearing steel strand, stabilizing steel strand, and inclined wind-resistant steel strand all adopt a 7-wire prestressed structure. The outer surface of each steel wire in each steel strand is coated with a zinc-aluminum-magnesium-rare earth alloy composite coating. The strand gaps formed by the stranding are filled with neutral anti-corrosion lubricating grease. The outer periphery of the stranded steel strand is continuously covered with a high-density polyethylene weather-resistant sheath, so that the anti-corrosion layer on the surface of the steel wire, the anti-corrosion filling medium, and the weather-resistant sheath form a layered protective structure from the inside to the outside along the radial direction of the steel strand.

5. The corrosion-resistant and fatigue-resistant prestressed steel strand system according to claim 4, characterized in that, The total thickness of the zinc-aluminum-magnesium rare earth alloy composite coating is not less than 85 μm, and it contains lanthanum and cerium as coating modification components. The individual steel wires in each steel strand adopt a micro-arc transition stranding structure, and a stranding gap is formed between adjacent steel wires for filling with the neutral anti-corrosion lubricant. The high-density polyethylene weather-resistant sheath covers the outer periphery of the steel strand after stranding and gap filling are completed.

6. The anti-corrosion and fatigue-resistant prestressed steel strand system according to claim 1, characterized in that, The cable force dynamic compensation limiting node is set at the layered anchorage position of the steel structure column. The buffer clamp is sleeved on the outer periphery of the corresponding steel strand and allows the corresponding steel strand to slide relative to each other along the axial direction. A polyurethane buffer bushing is provided on the inner side of the buffer clamp to contact the corresponding steel strand. The elastic compensation component is a disc spring compensation component disposed between the buffer clamp and the steel structure support unit. The disc spring compensation component undergoes elastic deformation when the corresponding steel strand undergoes axial displacement, and applies axial compensation force to the corresponding steel strand through a pre-compression state.

7. The corrosion-resistant and fatigue-resistant prestressed steel strand system according to claim 6, characterized in that, The sealed and anti-corrosion composite anchor includes a tensioning end anchor set at the tensioning end of the steel strand and a fixed end extrusion anchor set at the fixed end of the steel strand. The steel strand inlet and outlet of both the tensioning end anchor and the fixed end extrusion anchor are equipped with double-layer rubber O-rings, and the steel strand extension position is covered with a heat-shrinkable sealing sleeve. The heat-shrinkable sealing sleeve is filled with epoxy anti-corrosion paste. The epoxy anti-corrosion paste is filled between the end of the steel strand and the corresponding anchor, so that the double-layer rubber O-ring, heat-shrinkable sealing sleeve and epoxy anti-corrosion paste form a continuous sealing structure along the path of the steel strand into the anchor.

8. The anti-corrosion and fatigue-resistant prestressed steel strand system according to claim 1, characterized in that, The synchronous tensioning positioning fixture includes a double-jack synchronous tensioning base symmetrically arranged at both ends of the steel strand, and the tensioning actuator consists of jacks respectively installed on the double-jack synchronous tensioning base and acting on both ends of the steel strand. The cable force sensor collects the tension force at both ends of the steel strand, and the laser rangefinder collects the anti-arch state at the mid-span of the steel strand. The double jack synchronous tensioning base adjusts the tension load of the corresponding jack according to the comparison results of the tension forces at both ends and the anti-arch state at the mid-span.

9. The corrosion-resistant and fatigue-resistant prestressed steel strand system according to claim 8, characterized in that, The dual-jack synchronous tensioning base is configured to control the two-end jacks to perform initial tensioning, secondary tensioning and final tensioning in sequence according to 30%, 65% and 100% of the design prestress, with each level of tensioning held and stabilized for 10 minutes. The cable force sensor synchronously collects the tension force at both ends of the steel strand during each tensioning stage. When the difference in tension force between the two ends is not greater than 3%, the next tensioning stage begins. When the difference in tension force between the two ends is greater than 3%, the tensioning load of the corresponding jack is adjusted and re-compared. At the same time, the tensioning load at both ends is adjusted based on the mid-span anti-arch state collected by the laser ranging device.

10. A construction method for the anti-corrosion and fatigue-resistant prestressed steel strand system according to any one of claims 1 to 9, characterized in that, The main load-bearing steel strand, the stabilizing steel strand, and the inclined wind-resistant steel strand are respectively installed at the corresponding layered anchoring positions, and the steel strands are kept radially limited and axially sliding at the intermediate support position. The tensioning actuators at both ends of the steel strand perform graded synchronous tensioning. In each tensioning stage, the cable force at both ends and the mid-span anti-arch state are obtained. When the difference in cable force at both ends meets the preset synchronous conditions, the next tensioning stage is entered. When the conditions are not met, the tensioning load at both ends is adjusted and re-compared. At the same time, the tensioning load is adjusted according to the mid-span anti-arch state. After the final tensioning is completed, lock and seal the anti-corrosion composite anchor and seal the ends of the steel strand, and adjust the preload state of the elastic compensation component; After settling, the cable tension is retested. If the cable tension deviation exceeds the preset retest conditions, the elastic compensation component is adjusted. Construction is completed when the cable tension deviation does not exceed the preset retest conditions.

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