Multi-purpose loading test device and method for large-span bridge cable system substructure

Abstract

The invention discloses a multi-purpose loading test device and method for a large-span bridge cable system substructure, and relates to the technical field of bridge cable loading tests. The test device comprises a cable system stress loading system, a cross beam electric lifting locking system and a roller bearing transmission system, wherein the cable system stress loading system comprises a cable system self-balancing reaction frame, a free rotation force boundary subsystem, a free rotation anchoring subsystem and a sling force loading anchoring subsystem. Through physical designs such as self-balancing reaction frames, composite anchor rings and variable cross-section force transmission of the cable system, the force transmission path and the stress capacity of the reaction frames are optimized, the loading capacity of the whole loading system is increased to thousands of tons, and the loading diameter breaks through 500 mm; meanwhile, the free rotation force boundary subsystem and the free rotation anchoring subsystem can freely rotate in the sliding cross beam, and hovering tensioning at any angle can be achieved when the cable substructure is loaded in cooperation with free sliding of the sliding cross beam.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge cable loading tests, and in particular to a multi-purpose loading test device and method for a substructure of a cable system of a large-span bridge. Background Art

[0002] The cable substructure of cable-supported bridges, such as long-span suspension bridges and cable-stayed bridges, is the core element responsible for the overall load-bearing capacity of the bridge. Its mechanical properties directly impact the safety of the entire bridge. With the continuous growth of bridge spans and load demands, cable diameters can exceed 1000 mm, and design loads can reach 10,000 tons. Traditional testing methods, due to insufficient equipment load capacity, limited model size, and stress concentration in the anchorage area, have difficulty accurately reflecting the damage evolution of the entire bridge under load.

[0003] The existing technical bottlenecks are mainly reflected in the following aspects: First, conventional loading devices are mostly designed for single components or small-sized cables and are not suitable for full-scale model tests of large-diameter cables. In addition, their load application capacity is insufficient, resulting in test results that cannot reflect the nonlinear response and collaborative working characteristics of the cable system in real engineering.

[0004] Secondly, stress concentration is easily generated in the anchoring area due to the diameter transition, and the failure mode deviates from the actual working conditions. However, the traditional reaction frame structure has insufficient stiffness, making it difficult to eliminate the interference of local deformation on the test data.

[0005] Third, the current cable loading method has a significant boundary condition distortion problem: during the test, the cables are completely rigidly fixed at both ends and then tensioned horizontally, while the cables actually in service in the bridge are in the shape of a catenary under the action of gravity and have a certain inclination angle. This difference leads to two fundamental deviations: (1) initial state distortion: horizontal tensioning forces the cables to be in a pure axial tension state, masking the stress distribution differences caused by the deadweight of actual suspended or inclined cables; (2) boundary constraints are too strong: the rigid fixed boundary is seriously inconsistent with the actual service life boundary of the cable. The above deviations will cause the test results to deviate significantly from the actual scenario and draw erroneous scientific conclusions.

[0006] Fourth, the existing test system lacks the ability to adapt to multiple working conditions and is unable to quickly switch between different substructure models such as the main cable-suspender system of a suspension bridge, the cables of a cable-stayed bridge, and the cables of a cable-arch bridge, resulting in low test efficiency and poor data comparability.

[0007] To address the above issues, there is an urgent need to develop a multi-purpose flexible boundary loading test device suitable for large-tonnage and large-size cable system substructures, which can restore the boundary conditions of the cables under actual service conditions, so as to break through the size and load limitations of traditional tests, truly restore the stress scenario of the entire bridge, and provide reliable support for bridge design optimization and safety assessment. Summary of the Invention

[0008] In view of this, the present invention provides a multi-purpose loading test device and method for a cable system substructure of a large-span bridge, aiming to solve the above-mentioned technical problems.

[0009] The multi-purpose loading test device for the cable system substructure of a long-span bridge proposed in accordance with the purpose of the present invention comprises a cable system stress loading system, a beam electric lifting and locking system, and a roller support transmission system; wherein: The cable system stress loading system includes a cable system self-balancing reaction frame, a free rotation force boundary subsystem, a free rotation anchoring subsystem and a sling force loading anchoring subsystem; The crossbeam electric lifting and locking system includes a screw-linked synchronous lifting subsystem; The roller supporting transmission system includes an adjustable roller bearing platform and a roller group.

[0010] Preferably, the cable system self-balancing reaction frame includes two groups of symmetrically arranged rectangular lattice frames, the bottom of the two groups of rectangular lattice frames are installed with bases, the two bases are connected by a box-type bottom beam, and the tops of the two groups of rectangular lattice frames are connected by a main beam; the middle part of the two groups of rectangular lattice frames is provided with a sliding beam, and the sliding beam is free to slide and lock along the height direction of the rectangular lattice frame.

[0011] Preferably, the free-rotating force boundary subsystem and the free-rotating anchoring subsystem both include a composite anchor ring, which is installed in the sliding beam and rotates freely in the sliding beam, cooperating with the free sliding of the sliding beam to realize hovering tensioning at any angle when the cable model is loaded; the free-rotating force boundary subsystem also includes a first through-type jack and a loading-end double-stage gradient anchoring unit; the first through-type jack is fixedly installed in the composite anchor ring, and the loading-end double-stage gradient anchoring unit includes a loading-end primary anchor and a loading-end secondary anchor, which are respectively arranged on both sides of the first through-type jack; the free-rotating anchoring subsystem also includes an anchoring-end anchor.

[0012] Preferably, variable-section force transmission spindles are fixedly installed on both sides of the composite anchor ring, and the variable-section force transmission spindles include a quadrangular pyramid force transmission section fixedly connected to the composite anchor ring and a cylindrical rotating section fixedly connected to the quadrangular pyramid force transmission section, and the cylindrical rotating section passes through the sliding beam and rotates freely in the sliding beam.

[0013] Preferably, the cable force loading and anchoring subsystem includes a second through-type jack, a cable loading end anchor and a locking anchoring mechanism; the second through-type jack is embedded in the internal cavity of the box-type bottom beam, and the cable loading end anchor is anchored at the end of the cable model, and its outer diameter is smaller than the inner diameter of the second through-type jack; the locking anchoring mechanism is arranged between the second through-type jack and the cable loading end anchor, and its inner diameter is equal to the diameter of the cable model, and its outer diameter is larger than the outer diameter of the second through-type jack.

[0014] Preferably, the sling force loading anchoring subsystem also includes a T-shaped slide rail and a slide rail limiter, the T-shaped slide rail is fixedly installed on the box-type bottom beam, the slide rail limiter is installed on the T-shaped slide rail, and the second through-type jack moves on the T-shaped slide rail and is limited and fixed by the slide rail limiter.

[0015] Preferably, the electric lifting and locking system of the beam is provided with two groups corresponding to the sliding beam, and each group of the electric lifting and locking system of the beam includes a screw-linked synchronous lifting subsystem, a limit sliding rail and an array-type positioning hole group; the screw-linked synchronous lifting subsystem includes a screw, an elevator, a motor and a base; the screw is symmetrically provided with two, one end of each screw is rotatably connected to the sliding beam through a flange, and the other end of the screw is connected to the elevator; the elevator is provided with two corresponding screws, and the motor links the two elevators through a transmission shaft; the base is fixedly installed on the top of the rectangular lattice frame, and the elevator and motor are fixedly installed on the base; the limit sliding rail is integrated on the inner side of the rectangular lattice frame, and forms a sliding pair with the slider at the end of the sliding beam; the array-type positioning hole group is evenly spaced along the height direction of the rectangular lattice frame, and cooperates with the detachable latch mechanism on the sliding beam to lock the position of the sliding beam.

[0016] Preferably, the base height is lower than the box-type bottom beam, and the adjustable roller bearing platforms are at least two symmetrically installed on the outside of the base, and each adjustable roller bearing platform includes a base frame, a lifting mechanism and a top bearing beam; the base frame is installed on the ground, and the lifting mechanism is arranged between the base frame and the top bearing beam. The top bearing beam moves up and down under the drive of the lifting mechanism. After the top bearing beam is lifted, the top bearing beam is at the same height as the box-type bottom beam; the roller group is installed on the adjustable roller bearing platform and the box-type bottom beam, and is a plurality of groups arranged at equal distances. The top bearing beam and the box-type bottom beam are both provided with concave slots for installing the roller group.

[0017] The present invention also discloses a method for performing a loading test using the multi-purpose loading test device for a large-span bridge cable system substructure. The method is applicable to separate tensioning of a main cable model or a sling model of a suspension bridge, composite tensioning of a main cable and sling model at any angle, suspended tensioning at any angle of a cable-stayed bridge cable model, and vertical tensioning of a sling arch bridge cable model. The method comprises the following steps: S1. Select or make a cable model according to the cable system required for the test; S2. Evenly attach several strain gauges to the stressed steel wires in any section of the cable model. S3. Assemble the self-balancing reaction frame of the cable system; S4. Use the electric lifting and locking system of the beam to synchronously lower the sliding beams on both sides to the base reference plane; install the roller support transmission system; S5. Install the cable model on the self-balancing reaction frame of the cable system; The installation method of a single main cable model or a stay cable model is as follows: first, a first through-type jack is embedded in the composite anchor ring of the free rotation force boundary subsystem and fixed, and a force sensor is installed at the front end of the first through-type jack; a loading end primary anchor is installed at the loading end of the model, and after the steel wire bundle is extended to pass through the loading end primary anchor, an anchor strain gauge is installed on each cable strand; an anchor end anchor is installed at the anchoring end of the model; then, the model is hoisted onto the adjustable roller bearing platform of the roller support transmission system, and the loading end of the model is directional placed on the side of the free rotation anchoring subsystem, and the model is pulled. With the assistance of multiple roller groups, the loading end of the model passes through the composite anchor ring of the free rotation anchoring subsystem and the first through-type jack of the free rotation force boundary subsystem in sequence, and the steel wire bundle is extended through the loading end of the first through-type jack to install the loading end secondary anchor; then, the electric lifting and locking system of the beam is activated to lift the sliding beam to any preset height, and the height of the sliding beam is adjusted to perform hovering tensioning of the model at any angle; finally, the roller support transmission system is removed; The single sling model installation method is as follows: First, a second through-type jack is embedded in the cavity inside the box-type bottom beam, and a force sensor is installed at the front end of the second through-type jack; then, a main cable model is installed as a loading auxiliary device to fix the upper end of the sling model; then, the sling model and the main cable model are connected by a cable clamp, and an anchor cable strain gauge and a sling loading end anchor are installed at the loading end of the sling model; finally, the sling loading end anchor is extended into the second through-type jack and locked by a locking anchor mechanism; The installation method of the main cable and sling composite model is as follows: the main cable model and the sling model are installed in sequence according to the installation method of the main cable model and the sling model, and the height of the sliding beam and the horizontal position of the second through-type jack are adjusted to perform joint tensioning of the main cable and sling composite model at any angle; S6. Install a displacement meter on the cable model; S7. Control the corresponding through-type jack to load in stages according to the displacement control mode, with the load increment of each stage not less than 5% of the design breaking force. After loading until the model stress reaches the minimum breaking force, switch to the force control mode and load at 5-10 kN per stage until the model breaks; S8. The collected axial force, displacement, and strand stress and strain data of the cable model are transmitted to a computer terminal in real time, and the strain and stress state of the cable model are monitored and drawn throughout the process; S9. Replace the loading end anchor, anchoring end anchor and sling loading end anchor to adapt to different cable models and apply different loads and constraints to different cable systems.

[0018] Compared with the prior art, the advantages of the multi-purpose loading test device and method for the cable system substructure of a large-span bridge disclosed in the present invention are: 1. Ability to achieve stress loading of large-scale cable systems with loads exceeding thousands of tons: Through the physical design of the cable system, such as the self-balancing reaction frame, composite anchor ring and variable cross-section force transmission, the force transmission path and load-bearing capacity of the reaction frame are optimized. This overturns the current situation in which the maximum loading capacity of the cable system is only hundreds of tons and the loading diameter is limited to ≤100mm. The loading capacity of the entire loading system has jumped to thousands of tons and the loading diameter has exceeded 500mm.

[0019] 2. Restore the stress boundary of the real cable during its service life: The free-rotating force boundary subsystem and the free-rotating anchoring subsystem rotate freely in the sliding beam through the variable-section force transmission main shaft. Combined with the free sliding of the sliding beam, it can realize multi-scenario simulation of cable loading: (1) Suspended tensioning at any angle when the main cable or inclined cable is loaded alone; (2) Suspended tensioning at any angle and multi-directional composite tensioning of the composite model of the main cable and sling; (3) Vertical tensioning under the real boundary of the sling.

[0020] 3. Versatility and adaptability: The test device is applicable to a variety of cable systems, such as suspension bridge cable systems, cable-stayed bridge cable systems, and suspender arch bridge cable systems. It can simulate mechanical behavior under different working conditions, enhancing the versatility of the test device. Furthermore, its modular design allows components such as the electric lifting and locking system for the crossbeam and the roller support transmission system to be quickly assembled and adjusted according to test requirements. This improves test efficiency, reduces the cost of re-purchasing and assembling test devices, and increases the utilization of test resources.

[0021] 4. Operational convenience and test efficiency: The electric crossbeam lifting and locking system uses a screw linkage to achieve synchronous and smooth lifting of the sliding crossbeam. The limited sliding track and array of positioning holes achieve high-precision positioning and locking, improving operational convenience and test stability. By replacing anchors to adapt to different cable system models, test conditions can be quickly switched, allowing multiple tests to be performed, improving test efficiency.

[0022] 5. Safety and Reliability: The loading, anchoring, and sling loading anchors all utilize self-locking, nonlinear anchoring, ensuring the stability and safety of the cable model during loading. Furthermore, through-hole jacks enable graded loading and high-precision force control, ensuring smooth and safe testing and preventing test failures caused by excessive loading.

[0023] 6. Support for bridge engineering design and assessment: Through multiple tests and data processing, it is possible to generate local and overall strain and stress curves for cables, and determine the damage evolution of the cable system from stress to failure under different working conditions. This provides strong support for bridge design optimization and safety assessment, and solves problems such as insufficient equipment bearing capacity, limited model size, and stress concentration in the anchorage area in traditional testing methods. It breaks through the size and load limitations of traditional tests and truly restores the stress scenario of the entire bridge.

[0024] 7. High-precision and multi-dimensional monitoring: Integrated cable axial displacement, single-strand cable strain, and stress monitoring enable simultaneous acquisition of high-precision data, forming a multi-parameter collaborative monitoring system that comprehensively reflects the mechanical properties of the cable system. High-precision sensors and data acquisition systems ensure the accuracy and reliability of test data, providing high-quality data support for subsequent analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a schematic diagram of the overall structure provided by the present invention.

[0027] Figure 2 This is a structural schematic diagram of the electric lifting and locking system for the beam provided by the present invention.

[0028] Figure 3 This is a structural schematic diagram of the adjustable roller bearing platform provided by the present invention.

[0029] Figure 4 This is a structural schematic diagram of the composite anchor ring and variable-section force transmission spindle provided by the present invention.

[0030] Figure 5 This is a structural schematic diagram of the sling force loading anchoring subsystem provided by the present invention.

[0031] Figure 6 This is a schematic structural diagram of the free rotation force boundary subsystem provided by the present invention.

[0032] Figure 7 This is a structural schematic diagram of the main cable and sling composite model provided by the present invention.

[0033] In the picture: 1-Electric lifting and locking system for crossbeam; 2-Roller support transmission system; 3-Main cable and sling composite model; 4-Cable system self-balancing reaction frame; 5-Free rotation force boundary subsystem; 6-Free rotation anchoring subsystem; 7-Sling force loading anchoring subsystem; 11-limited sliding track; 12-array positioning hole group; 13-screw linkage synchronous lifting subsystem; 131-base; 132-screw; 133-motor; 134-drive shaft; 135-reducer; 136-elevator; 21-Adjustable roller bearing platform; 22-Roller assembly; 211-Base frame; 212-Top bearing beam; 213-Lifting rod; 214-Knob; 215-Support column; 23-Concave slot; 31-main cable model; 311-cable strand; 312-first steel wire; 313-second steel wire; 32-sling model; 33-cable clamp; 41-main beam; 42-column; 43-fixing hole; 44-upper beam; 45-base; 46-box bottom beam; 47-sliding beam; 48-fixing seat; 51-composite anchor ring; 52-quadrangular pyramid force transmission section; 53-cylindrical rotation section; 54-first through-type jack; 55-primary anchor at the loading end; 56-secondary anchor at the loading end; 61-anchor end anchor; 71-Second through-type jack; 72-T-shaped slide rail; 73-Slide rail limiter; 74-Sling loading end anchor; 75-Separable half ring group; 76-Driving rod. DETAILED DESCRIPTION

[0034] The following is a brief description of the specific embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are also within the scope of protection of the present invention.

[0035] Figure 1-Figure 7 The preferred embodiments of the present invention are shown and analyzed in detail.

[0036] like Figure 1The multi-purpose loading test device for cable substructures of large-span bridges shown is suitable for multi-purpose loading tests on cable substructures with large tonnages of 800-1000t and diameters of 500-600mm. The test device includes a cable system stress loading system, a crossbeam electric lifting and locking system 1, and a roller support transmission system 2.

[0037] The cable system stress loading system includes a cable system self-balancing reaction frame 4, a free rotation force boundary subsystem 5, a free rotation anchoring subsystem 6 and a sling force loading anchoring subsystem 7.

[0038] The cable system self-balancing reaction frame 4 comprises two symmetrically arranged rectangular lattice frames. Each set of rectangular lattice frames includes four steel box columns 42 arranged in a rectangular pattern, with supports provided between adjacent columns 42. Upper crossbeams 44 are bolted to the tops of the columns 42. The tops of the two sets of rectangular lattice frames are connected by two main crossbeams 41. The bottoms of both sets of rectangular lattice frames are installed with an integral base 45 formed by a box-shaped steel platform. The two bases 45 are connected by a box-shaped bottom beam 46, which is lower than the box-shaped bottom beam 46. A sliding crossbeam 47 is installed in the middle of each set of rectangular lattice frames. Driven by the electric crossbeam lifting and locking system 1, the sliding crossbeam 47 can slide freely and lock in the vertical direction within the rectangular lattice frame.

[0039] The free rotation force boundary subsystem 5 and the free rotation anchoring subsystem 6 are used to anchor and load the main cable model 31 or the inclined cable model. The free rotation force boundary subsystem 5 and the free rotation anchoring subsystem 6 both include a composite anchor ring 51. Figure 4 As shown, the composite anchor ring 51 has a square frame on the outside and a circular through-hole on the inside. A variable-section force transmission spindle is fixedly installed on both sides of the composite anchor ring 51. The variable-section force transmission spindle includes a quadrangular pyramid force transmission section 52 welded to the composite anchor ring 51 and a cylindrical rotation section 53 welded to the quadrangular pyramid force transmission section 52. The outer surface of the quadrangular pyramid force transmission section 52 is evenly distributed with radial stiffening ribs. The cylindrical rotation section 53 passes through the sliding beam 47 and rotates freely around the axis of the cylindrical rotation section 53 within the sliding beam 47 through a sleeve or bearing structure, thereby driving the composite anchor ring 51 to rotate freely within the sliding beam 47. Combined with the free sliding of the sliding beam 47, the cable model can be suspended and tensioned at any angle when loaded. The free-rotating force boundary subsystem 5 and the free-rotating anchoring subsystem 6 both adopt the variable-section force transmission spindle and composite anchor ring 51 design, which can achieve free rotation and anchoring of the cable model during loading, simulating the mechanical behavior under actual working conditions. The design of the variable-section force transmission spindle enables it to adaptively transmit force during loading, improving the flexibility and adaptability of the test device.

[0040] like Figure 6As shown, the free-rotation force boundary subsystem 5 also includes a first through-hole jack 54 and a loading-end dual-stage gradient anchoring unit. The first through-hole jack 54 is fixedly mounted via a flange within a circular through-hole within the composite anchor ring 51. The inner diameter of the circular through-hole matches the outer diameter of the first through-hole jack 54. The loading-end dual-stage gradient anchoring unit includes a loading-end primary anchor 55 and a loading-end secondary anchor 56, which are positioned on either side of the first through-hole jack 54 to anchor the main cable model 31 or the cable-stayed cable model. The outer diameter of the loading-end primary anchor 55 is smaller than the inner diameter of the first through-hole jack 54 and the inner diameter of the composite anchor ring 51 in the free-rotation anchoring subsystem 6. The outer diameter of the loading-end secondary anchor 56 is 1.2-1.5 times the outer diameter of the flange on the first through-hole jack 54. The steel wire bundle of the main cable model 31 or the inclined cable model extends outward through the primary anchor 55 at the loading end, passes through the inner cavity of the first through-type jack 54, and is finally anchored by the secondary anchor 56 at the loading end. The first through-type jack 54 pushes the secondary anchor 56 at the loading end to realize the axial force loading of the main cable model 31 or the inclined cable model. During the loading process, the variable-section force transmission main shaft can rotate freely around the axis. The design of the double-stage gradient anchoring unit at the loading end improves the reliability and safety of the anchoring through the synergistic effect of the primary anchor 55 at the loading end and the secondary anchor 56 at the loading end. The first through-type jack 54 pushes the secondary anchor 56 at the loading end to realize the axial force loading of the main cable model 31 or the inclined cable model, which can accurately control the magnitude of the loading force and ensure the accuracy of the test.

[0041] The free-rotating anchoring subsystem 6 further includes an anchoring end anchor 61 for anchoring the main cable model 31 or the anchoring end of the inclined cable model. The outer diameter of the anchoring end anchor 61 is 1.2 times the inner diameter of the composite anchor ring 51 in the free-rotating anchoring subsystem 6.

[0042] like Figure 5 As shown, the sling force loading anchoring subsystem 7 includes a second through-type jack 71, a sling loading end anchor 74, a locking anchoring mechanism, a T-shaped slide rail 72, and a slide rail limiter 73. The second through-type jack 71 is embedded in the internal cavity of the box-type bottom beam 46, and the sling loading end anchor 74 is anchored to the end of the sling model 32. The inner diameter of the second through-type jack 71 is 1.1-1.2 times the outer diameter of the sling loading end anchor 74. The locking anchoring mechanism is arranged between the second through-type jack 71 and the sling loading end anchor 74. Its inner diameter is equal to the diameter of the sling model 32, and its outer diameter is larger than the outer diameter of the second through-type jack 71. The setting of the locking anchoring mechanism can realize the self-locking and release of the sling model 32, ensuring the stability of the sling model 32 during the loading process and the rapid release after unloading.

[0043] The locking anchoring mechanism consists of a detachable half-ring assembly 75 connected by a lever 76 and positioned within the box-type bottom beam 46. The lever 76 drives the detachable half-ring assembly 75 to open and close radially, achieving both release and self-locking functions. After the sling loading end anchor 74 anchors the sling model 32, it passes through the second through-type jack 71 as a whole. The levers 76 on either side of the opening above the box-type bottom beam 46 are moved to close the detachable half-ring assembly 75. The annular locking surface formed by the detachable half-ring assembly 75 is inserted between the sling loading end anchor 74 and the second through-type jack 71, preventing the loading end of the sling model 32 from being pulled out from the second through-type jack 71. The second through-type jack 71 can then load the sling model 32. Reversely moving the lever 76 drives the detachable half-ring assembly 75 to separate, releasing the loading end of the sling model 32 and allowing the sling model 32 to be freely withdrawn axially. The locking anchor mechanism drives the radial opening and closing of the detachable half-ring assembly 75 via a lever 76, achieving both release and self-locking functions for the sling model 32. This improves the anchoring reliability and operational flexibility of the sling model 32. The design of this locking anchor mechanism facilitates replacement and adaptation of the sling model 32, enhancing the versatility of the test device. During implementation, the locking anchor mechanism can be manually opened and closed by manually accessing the box-type bottom beam 46. When the detachable half-ring assembly 75 in the locking anchor mechanism is closed, it is connected and secured by a conventional snap-fit ​​device positioned between them.

[0044] The T-shaped slide rail 72 is fixedly mounted on the box-shaped bottom beam 46. Two slide rail limiters 73 are provided, symmetrically mounted at both ends of the T-shaped slide rail 72. The slide rail limiters 73 are movable on the T-shaped slide rail 72 and rigidly fixed by bolts. The second through-type jack 71 is embedded in the internal cavity of the box-shaped bottom beam 46. After adjusting its position horizontally on the T-shaped slide rail 72 as needed, it is rigidly connected to the two slide rail limiters 73 by bolts. The slide rail limiters 73 are then rigidly connected to the T-shaped slide rail 72 by bolts, thereby limiting the horizontal position of the second through-type jack 71 on the T-shaped slide rail 72. The arrangement of the T-shaped slide rail 72 and the slide rail limiters 73 facilitates the adjustment and fixation of the second through-type jack 71, improving the loading stability and operational convenience of the sling model 32. At the same time, by adjusting the height of the sliding beam 47 and the horizontal position of the second through-type jack 71, the main cable and the sling composite model 3 can be tensioned at any angle.

[0045] The loading-end primary anchor 55, the loading-end secondary anchor 56, the anchoring-end anchor 61, and the sling loading-end anchor 74 have the same structure, all including an anchor ring and a conical clip assembly. Several conical through-holes are evenly distributed along the circumference of the anchor ring. The conical clip assembly is composed of two equally divided clips assembled to form a complete conical ring. The outer conical surface of the clip matches the inner conical surface of the conical through-hole of the anchor ring, and the inner wall of the clip is provided with a spiral friction groove. The stressed steel wire in the cable model passes through the conical clip assembly and the conical through-hole of the anchor ring. When loaded, the stressed steel wire drives the conical clip assembly toward the small end of the conical through-hole. The clip is radially squeezed and pressed against the conical through-hole of the anchor ring. The spiral friction groove forms a mechanical engagement with the surface of the stressed steel wire. Through the synergistic action of the anchor ring and the conical clip assembly, a self-locking nonlinear anchoring of the stressed steel wire is achieved, improving the safety and reliability of the test.

[0046] like Figure 2 As shown, two sets of electric crossbeam lifting and locking systems 1 are provided corresponding to the sliding crossbeam 47. Each set of electric crossbeam lifting and locking systems 1 includes a screw-linked synchronous lifting subsystem 13, a limited sliding track 11, and an array of positioning holes 12. The screw-linked synchronous lifting subsystem 13 includes a screw 132, an elevator 136, a motor 133, and a base 131. Two screws 132 are symmetrically provided, each of which is rotatably connected to the sliding crossbeam 47 via a flange at one end and connected to the elevator 136 at the other end. Two elevators 136 are provided corresponding to the screws 132. The motor 133 links the two elevators 136 via a transmission shaft 134 to control the smooth lifting and lowering of the sliding crossbeam 47. Specifically, the output end of the motor 133 is connected to the reducer 135, which transmits power to the reducer 135. The output ends of the reducer 135 are respectively connected to the turbine boxes in the two elevators 136 through two drive shafts 134. The motor 133 rotates to drive the turbine box to drive the screw rod 132 to move linearly, thereby driving the sliding beam 47 to rise and fall smoothly, improving the stability of the test device and the convenience of operation. The base 131 is fixedly mounted on the top beam 44 of the rectangular lattice frame, and the elevator 136 and the motor 133 are fixedly mounted on the base 131. The limited sliding track 11 is integrated into the inner side of the column 42 in the rectangular lattice frame. The cross section is T-shaped and forms a sliding pair with the slider at the end of the sliding beam 47. Arrayed positioning hole groups 12 are distributed on column 42 at equal intervals of 50-100 mm along the height of column 42. A fixing seat 48 is fixedly mounted on sliding beam 47. Fixing seat 48 is provided with fixing holes 43 that cooperate with arrayed positioning hole group 12 for positioning. A detachable latch mechanism is installed in fixing hole 43. Arrayed positioning hole group 12 cooperates with the detachable latch mechanism to lock the position of sliding beam 47. The use of limited sliding track 11 and arrayed positioning hole group 12 in combination can accurately control the position of sliding beam 47 and lock the position through the detachable latch mechanism, ensuring the stability of the device during the test.

[0047] The roller supporting transmission system 2 includes an adjustable roller bearing platform 21 and a roller group 22. Figure 3 As shown, two adjustable roller bearing platforms 21 are provided, symmetrically mounted on the outside of the two bases 45. Each adjustable roller bearing platform 21 includes a base frame 211, a lifting mechanism, and a top bearing beam 212. The base frame 211 is fixed to the ground with bolts. The lifting mechanism is provided between the base frame 211 and the top bearing beam 212 to drive the top bearing beam 212 to move up and down. When the top bearing beam 212 is lifted by the lifting mechanism, it is at the same height as the box-type bottom beam 46. The lifting mechanism can be any of the existing technologies that can achieve this function. In this embodiment, the lifting mechanism includes four sets of support columns 215 and lifting rods 213, which are respectively arranged at the four corners of the base frame 211. The support columns 215 are rectangular steel columns fixedly mounted on the base frame 211. The columns are hollow inside. The lifting rods 213 are racks, one end of which is set inside the columns and the other end is fixedly connected to the top support beam 212. The columns are also provided with gears that cooperate with the gears. The surface of the support columns 215 is provided with a knob 214 for driving the gears. Turning the knob 214 can raise and lower the top support beam 212. The roller groups 22 are hourglass-shaped and are installed on the adjustable roller support platform 21 and the box-type bottom beam 46. They are arranged in multiple groups equidistantly along the length of the main cable model 31. Each roller group 22 includes two rollers. Both the top support beam 212 and the box-shaped bottom beam 46 are equipped with concave slots 23 for mounting the roller assembly 22. The width of the slots 23 matches the roller shaft diameter. The hourglass-shaped roller assembly 22 is designed to stably support and drive the cable model, ensuring smooth movement during testing.

[0048] A method for performing a loading test using the multi-purpose loading test device for the cable system substructure of a large-span bridge is disclosed, which is suitable for separate tensioning of a main cable model 31 or a sling model 32 of a suspension bridge, composite tensioning of a main cable and sling composite model 3 at any angle, and suspended tensioning at any angle of a cable-stayed bridge cable model; and vertical tensioning test of a sling model 32 of a cable-stayed arch bridge.

[0049] The test method specifically includes the following steps: S1. Select or fabricate a cable model based on the cable system to be loaded in the test. The main cable model 31 or the stay-cable model consists of multiple strands 311 of the same diameter and length. The spaces between each strand 311 are uniformly and densely filled with non-load-bearing first steel wires 312, with a fill ratio of 60-70%. A second steel wire 313 is wrapped around the outer surface of the model to complete the main cable model 31 or the stay-cable model, achieving a 1:1 resemblance between the model and the actual deadweight during service. The sling model 32 is constructed directly from real slings, without the need for separate fabrication.

[0050] S2. Evenly attach several strain gauges to the stressed steel wires in any section of the cable model to monitor the strain changes of the stressed steel wires during the tensioning process, thereby determining the overall stress situation and uniformity of the cable model.

[0051] S3. Assemble the self-balancing reaction frame 4 of the cable system.

[0052] S4. Synchronously lower the sliding beams 47 on both sides to the reference plane of the base 45 through the beam electric lifting and locking system 1; install the roller support transmission system 2, and lift the top bearing beam 212 on the adjustable roller bearing platform 21 to the same height as the box-type bottom beam 46.

[0053] S5. Install the cable model onto the self-balancing reaction frame 4 of the cable system: The installation method for a single main cable model 31 or a stay cable model is as follows: First, a first through-hole jack 54 is embedded and secured within the composite anchor ring 51 of the free-rotation force boundary subsystem 5. A force sensor is installed at the front end of the first through-hole jack 54. The force sensor is connected to a load display recorder to monitor the axial force applied by the first through-hole jack 54. A loading-end primary anchor 55 is installed at the loading end of the main cable model 31 or the stay cable model. After the cable strands 311 pass through the loading-end primary anchor 55, an anchor strain gauge is installed on each cable strand 311 to monitor stress changes in each cable strand 311 of the main cable model 31 or the stay cable model during the test. An anchor-end anchor 61 is installed at the anchoring end of the main cable model 31 or the stay cable model. Next, the main cable model 31 or the stay-cable model is hoisted onto the platform of the roller support transmission system 2. The loading end of the main cable model 31 or the stay-cable model is oriented and placed beside the free-rotating anchoring subsystem 6. The main cable model 31 or the stay-cable model is then pulled. With the assistance of multiple roller assemblies 22, the loading end of the main cable model 31 or the stay-cable model sequentially passes through the composite anchor ring 51 of the free-rotating anchoring subsystem 6 and the first through-hole jack 54 in the free-rotating force boundary subsystem 5. The loading end strand 311 of the first through-hole jack 54 is then installed with the loading end secondary anchor 56. Next, the electric crossbeam lifting and locking system 1 is activated to raise the sliding crossbeam 47 to any preset height. The height of the sliding crossbeam 47 is then adjusted to allow the main cable model 31 or the stay-cable model to be suspended and tensioned at any angle. Finally, the roller support transmission system 2 is removed.

[0054] The installation method of a single sling model 32 is as follows: first, a second through-type jack 71 is embedded in the internal cavity of the box bottom beam 46, and a force sensor is installed at the front end of the second through-type jack 71. The force sensor is connected to a load display recorder to monitor the axial force applied by the second through-type jack 71; then, a main cable model 31 is installed according to the installation method of the main cable model 31 as a loading auxiliary tool for fixing the upper end of the sling model 32; because the main cable model 31 is only an auxiliary tool for the sling model 32, its stress condition is not of concern, so the force sensor at the front end of the first through-type jack 54 and the strain gauge and anchor strain gauge on the main cable model 31 can be chosen not to be installed; then, the sling model 32 and the main cable model 31 are connected by a cable clamp 33, and the anchor strain gauge and the sling loading end anchor 74 are installed at the loading end of the sling model 32; finally, the sling loading end anchor 74 is extended into the second through-type jack 71 and locked by a locking anchoring mechanism.

[0055] like Figure 7 The installation method of the main cable and sling composite model 3 shown is: install the main cable model 31 and the sling model 32 in sequence according to the installation method of the main cable model 31 and the sling model 32, and adjust the height of the sliding beam 47 and the horizontal position of the second through-type jack 71 to perform joint tensioning of the main cable and sling composite model 3 at any angle.

[0056] S6. Install displacement meters at preset positions of the cable model, such as the mid-span of the main cable model 31 and the end of the sling model 32.

[0057] S7. Control the corresponding through-hole jacks to load in stages using the displacement control mode according to the test requirements. When testing a single main cable model 31 or a stay cable model, control the first through-hole jack 54 to load. When testing a single sling model 32, control the second through-hole jack 71 to load. When testing a combined main cable and sling model 3, control the first through-hole jack 54 and the second through-hole jack 71 to load. Each load increment is 5% of the design breaking force. After loading the model until the stress reaches the minimum breaking force, switch to force control mode and load the model at 5-10 kN increments until the model breaks.

[0058] S8. The collected axial force, displacement, and stress-strain data of the cable model are transmitted to the computer terminal in real time, and the strain and stress state of the cable model are monitored and drawn throughout the process.

[0059] S9. Replace the loading end anchor, the anchoring end anchor 61 and the sling loading end anchor 74 to adapt to different cable models and apply different loads and constraints to different cable systems.

[0060] The above description of the disclosed embodiments will enable one skilled in the art to implement and use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest possible manner consistent with the principles and novel features disclosed herein.

Claims

1. Multipurpose loading test device for cable substructure of large-span bridge, characterized by: It includes a cable system stress loading system, a beam electric lifting and locking system, and a roller support transmission system; among which: The cable system stress loading system includes a cable system self-balancing reaction frame, a free rotation force boundary subsystem, a free rotation anchoring subsystem and a sling force loading anchoring subsystem; The crossbeam electric lifting and locking system includes a screw-linked synchronous lifting subsystem; The roller supporting transmission system includes an adjustable roller bearing platform and a roller group.

2. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 1 is characterized in that: The cable system self-balancing reaction frame includes two groups of symmetrically arranged rectangular lattice frames, the bottom of the two groups of rectangular lattice frames are installed with bases, the two bases are connected by a box-type bottom beam, and the tops of the two groups of rectangular lattice frames are connected by a main beam; the middle of the two groups of rectangular lattice frames are provided with sliding beams, and the sliding beams are free to slide and lock along the height direction of the rectangular lattice frames.

3. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 2 is characterized in that: The free rotation force boundary subsystem and the free rotation anchoring subsystem both include a composite anchor ring, which is installed in the sliding beam and rotates freely in the sliding beam, cooperating with the free sliding of the sliding beam to realize hovering tensioning at any angle when the cable model is loaded; the free rotation force boundary subsystem also includes a first through-type jack and a loading end double-stage gradient anchoring unit; the first through-type jack is fixedly installed in the composite anchor ring, and the loading end double-stage gradient anchoring unit includes a loading end primary anchor and a loading end secondary anchor, which are respectively arranged on both sides of the first through-type jack; the free rotation anchoring subsystem also includes an anchor end anchor.

4. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 3 is characterized in that: Variable-section force transmission spindles are fixedly installed on both sides of the composite anchor ring. The variable-section force transmission spindles include a quadrangular pyramid force transmission section fixedly connected to the composite anchor ring and a cylindrical rotating section fixedly connected to the quadrangular pyramid force transmission section. The cylindrical rotating section passes through the sliding beam and rotates freely in the sliding beam.

5. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 2 is characterized in that: The cable force loading and anchoring subsystem includes a second through-type jack, a cable loading end anchor and a locking anchoring mechanism; the second through-type jack is embedded in the internal cavity of the box-type bottom beam, and the cable loading end anchor is anchored at the end of the cable model, and its outer diameter is smaller than the inner diameter of the second through-type jack; the locking anchoring mechanism is arranged between the second through-type jack and the cable loading end anchor, and its inner diameter is equal to the diameter of the cable model, and its outer diameter is larger than the outer diameter of the second through-type jack.

6. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 5 is characterized in that: The sling force loading anchoring subsystem also includes a T-shaped slide rail and a slide rail limiter. The T-shaped slide rail is fixedly installed on the box-type bottom beam, and the slide rail limiter is installed on the T-shaped slide rail. The second through-type jack moves on the T-shaped slide rail and is limited and fixed by the slide rail limiter.

7. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 2 is characterized in that: The electric lifting and locking system of the beam is provided with two groups corresponding to the sliding beam, and each group of the electric lifting and locking system of the beam includes a screw-linked synchronous lifting subsystem, a limit sliding rail and an array-type positioning hole group; the screw-linked synchronous lifting subsystem includes a screw, an elevator, a motor and a base; two screws are symmetrically provided, and one end of each screw is rotatably connected to the sliding beam through a flange, and the other end of the screw is connected to the elevator; two elevators are provided corresponding to the screws, and the motor links the two elevators through a transmission shaft; the base is fixedly installed on the top of the rectangular lattice frame, and the elevator and motor are fixedly installed on the base; the limit sliding rail is integrated on the inner side of the rectangular lattice frame, and forms a sliding pair with the slider at the end of the sliding beam; the array-type positioning hole group is evenly distributed along the height direction of the rectangular lattice frame, and cooperates with the detachable latch mechanism on the sliding beam to lock the position of the sliding beam.

8. The multi-purpose loading test device for cable substructure of a long-span bridge according to claim 2 is characterized in that: The height of the base is lower than the box-type bottom beam, and the adjustable roller bearing platforms are at least two symmetrically installed on the outside of the base, and each adjustable roller bearing platform includes a base frame, a lifting mechanism and a top bearing beam; the base frame is installed on the ground, and the lifting mechanism is arranged between the base frame and the top bearing beam. The top bearing beam moves up and down under the drive of the lifting mechanism. After the top bearing beam is lifted, the top bearing beam is at the same height as the box-type bottom beam; the roller group is installed on the adjustable roller bearing platform and the box-type bottom beam, and is a plurality of groups arranged at equal distances. The top bearing beam and the box-type bottom beam are both provided with concave slots for mounting the roller group.

9. A method for conducting a loading test using the multipurpose loading test device for a large-span bridge cable system substructure according to any one of claims 1 to 8, characterized in that: The method is applicable to the separate tensioning of the main cable model or the sling model of a suspension bridge, the arbitrary-angle composite tensioning of the main cable and sling composite model, the arbitrary-angle suspended tensioning of the cable-stayed model of a cable-stayed bridge, and the vertical tensioning test of the sling model of a cable-arch bridge. The method comprises the following steps: S1. Select or make a cable model according to the cable system required for the test; S2. Evenly attach several strain gauges to the stressed steel wires in any section of the cable model. S3. Assemble the self-balancing reaction frame of the cable system; S4. Use the electric lifting and locking system of the beam to synchronously lower the sliding beams on both sides to the base reference plane; install the roller support transmission system; S5. Install the cable model on the self-balancing reaction frame of the cable system; The installation method of a single main cable model or a stay cable model is as follows: first, a first through-type jack is embedded in the composite anchor ring of the free rotation force boundary subsystem and fixed, and a force sensor is installed at the front end of the first through-type jack; a loading end primary anchor is installed at the loading end of the model, and after the steel wire bundle is extended to pass through the loading end primary anchor, an anchor strain gauge is installed on each cable strand; an anchor end anchor is installed at the anchoring end of the model; then, the model is hoisted onto the adjustable roller bearing platform of the roller support transmission system, and the loading end of the model is directional placed on the side of the free rotation anchoring subsystem, and the model is pulled. With the assistance of multiple roller groups, the loading end of the model passes through the composite anchor ring of the free rotation anchoring subsystem and the first through-type jack of the free rotation force boundary subsystem in sequence, and the steel wire bundle is extended through the loading end of the first through-type jack to install the loading end secondary anchor; then, the electric lifting and locking system of the beam is activated to lift the sliding beam to any preset height, and the height of the sliding beam is adjusted to perform hovering tensioning of the model at any angle; finally, the roller support transmission system is removed; The single sling model installation method is as follows: First, a second through-type jack is embedded in the cavity inside the box-type bottom beam, and a force sensor is installed at the front end of the second through-type jack; then, a main cable model is installed as a loading auxiliary device to fix the upper end of the sling model; then, the sling model and the main cable model are connected by a cable clamp, and an anchor cable strain gauge and a sling loading end anchor are installed at the loading end of the sling model; finally, the sling loading end anchor is extended into the second through-type jack and locked by a locking anchor mechanism; The installation method of the main cable and sling composite model is as follows: the main cable model and the sling model are installed in sequence according to the installation method of the main cable model and the sling model, and the height of the sliding beam and the horizontal position of the second through-type jack are adjusted to perform joint tensioning of the main cable and sling composite model at any angle; S6. Install a displacement meter on the cable model; S7. Control the corresponding through-type jack to load in stages according to the displacement control mode, with the load increment of each stage not less than 5% of the design breaking force. After loading until the model stress reaches the minimum breaking force, switch to the force control mode and load at 5-10 kN per stage until the model breaks; S8. The collected axial force, displacement, and strand stress and strain data of the cable model are transmitted to a computer terminal in real time, and the strain and stress state of the cable model are monitored and drawn throughout the process; S9. Replace the loading end anchor, anchoring end anchor and sling loading end anchor to adapt to different cable models and apply different loads and constraints to different cable systems.

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