Multipurpose loading test apparatus and method for cable-stayed bridge substructures

Abstract

This invention discloses a multi-purpose loading test device and method for cable-stayed substructures of long-span bridges, relating to the field of bridge cable loading test technology. The test device includes a cable-stayed stress loading system, an electric lifting and locking system for the crossbeam, and a roller support and transmission system. The cable-stayed stress loading system comprises a self-balancing reaction frame, a free-rotational force boundary subsystem, a free-rotational anchoring subsystem, and a cable force loading and anchoring subsystem. Through physical design such as the self-balancing reaction frame, composite anchor rings, and variable cross-section force transmission, this invention optimizes the force transmission path and load-bearing capacity of the reaction frame, enabling the entire loading system to achieve a loading capacity of thousands of tons and a loading diameter exceeding 500 mm. Simultaneously, the free-rotational force boundary subsystem and the free-rotational anchoring subsystem can rotate freely within the sliding crossbeam, allowing for arbitrary angle suspension tensioning during cable substructure loading, in conjunction with the free sliding of the crossbeam.

Description

Technical Field

[0001] This invention relates to the field of bridge cable loading testing technology, specifically to a multi-purpose loading testing device and method for substructures of cable systems in long-span bridges. Background Technology

[0002] The cable system substructure of cable-stayed bridges and other cable-stayed bridges with long spans is the core unit of the overall stress of the bridge, and its mechanical properties directly affect the safety of the entire bridge. With the continuous increase in bridge span and load requirements, cable diameters can reach over 1000 mm, and design loads can reach tens of thousands of tons. Traditional testing methods are difficult to accurately reflect the damage evolution law under the stress state of the entire bridge due to problems such as insufficient equipment load-bearing capacity, limited model size, and stress concentration in the anchorage zone.

[0003] The existing technological bottlenecks are mainly reflected in the following aspects:

[0004] Firstly, conventional loading devices are mostly designed for single components or small-sized cables, which cannot be adapted to full-scale model tests of large-diameter cables. Furthermore, their load-bearing capacity is insufficient, resulting in test results that cannot reflect the nonlinear response and collaborative working characteristics of cable systems in real engineering projects.

[0005] Secondly, stress concentration is prone to occur in the anchorage zone due to the transition of diameter, and the failure mode deviates from the actual working conditions. The traditional reaction frame structure has insufficient stiffness and it is difficult to eliminate the interference of local deformation on the test data.

[0006] Third, the current cable loading method suffers from significant boundary condition distortion: during the test, the cable is horizontally tensioned after both ends are rigidly fixed, while the actual cable in service in the bridge is a catenary under gravity and has a certain angle of inclination. This difference leads to two fundamental deviations: (1) Initial state distortion: horizontal tension forces the cable into a pure axial tension state, which masks the stress distribution differences caused by the self-weight of the actual suspended or inclined cable; (2) Overly strong boundary constraints: 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 real scenario and lead to incorrect scientific conclusions.

[0007] Fourth, the existing test system lacks multi-condition adaptive capability and cannot quickly switch between different substructure models such as the main cable-suspender system of suspension bridges, the cable-stayed cables of cable-stayed bridges, and the suspenders of cable-stayed arch bridges, resulting in low test efficiency and poor data comparability.

[0008] To address the aforementioned issues, there is an urgent need to develop a multi-purpose flexible boundary loading test device suitable for large-tonnage, large-size cable system substructures, capable of reproducing the boundary conditions under actual cable service conditions. This device would overcome the size and load limitations of traditional tests, realistically reproduce the stress scenarios of the entire bridge, and provide reliable support for bridge design optimization and safety assessment. Summary of the Invention

[0009] In view of this, the present invention provides a multi-purpose loading test device and method for cable system substructures of long-span bridges, aiming to solve the above-mentioned technical problems.

[0010] The multi-purpose loading test device for the cable system substructure of long-span bridges, proposed according to the present invention, includes a cable system stress loading system, a crossbeam electric lifting and locking system, and a roller support transmission system; wherein:

[0011] 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;

[0012] The electric lifting and locking system for the crossbeam includes a screw-linked synchronous lifting subsystem.

[0013] The roller support transmission system includes an adjustable roller support platform and a roller assembly.

[0014] Preferably, the cable system self-balancing reaction frame includes two sets of symmetrically arranged rectangular lattice frames. The bottom of each set of rectangular lattice frames is equipped with a base, and the two bases are connected by a box-shaped bottom beam. The top of the two sets of rectangular lattice frames is connected by a main crossbeam. A sliding crossbeam is provided in the middle of each set of rectangular lattice frames. The sliding crossbeam can slide freely and lock along the height direction of the rectangular lattice frame.

[0015] Preferably, both the free rotation force boundary subsystem and the free rotation anchoring subsystem include a composite anchor ring, which is installed inside the sliding beam and rotates freely within the beam. This, combined with the free sliding of the beam, enables suspension tensioning at any angle during cable model loading. The free rotation force boundary subsystem also includes a first through-hole jack and a loading-end dual-gradient anchoring unit. The first through-hole jack is fixedly installed inside the composite anchor ring. The loading-end dual-gradient anchoring unit includes a primary loading-end anchor and a secondary loading-end anchor, which are respectively located on both sides of the first through-hole jack. The free rotation anchoring subsystem also includes an anchoring end anchor.

[0016] Preferably, a variable cross-section force transmission spindle is fixedly installed on both sides of the composite anchor ring. The variable cross-section force transmission spindle includes a truncated quadrangular force transmission section fixedly connected to the composite anchor ring and a cylindrical rotating section fixedly connected to the truncated quadrangular force transmission section. The cylindrical rotating section passes through the sliding crossbeam and rotates freely within the sliding crossbeam.

[0017] Preferably, the cable force loading and anchoring subsystem includes a second through-type jack, a cable loading end anchor, and a locking and anchoring mechanism; the second through-type jack is embedded in the internal cavity of the box-shaped bottom beam, the cable loading end anchor is anchored to the end of the cable model, and its outer diameter is smaller than the inner diameter of the second through-type jack; the locking and anchoring mechanism is disposed 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.

[0018] Preferably, the cable force loading anchoring subsystem further includes a T-shaped slide rail and a slide rail limiter. The T-shaped slide rail is fixedly installed on the box-shaped 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.

[0019] Preferably, the electric lifting and locking system for the crossbeam has two sets corresponding to the sliding crossbeam. Each set of the electric lifting and locking system includes a screw-driven synchronous lifting subsystem, a limiting sliding rail, and an array of positioning holes. The screw-driven synchronous lifting subsystem includes a screw, a lifting mechanism, a motor, and a base. Two screws are symmetrically arranged, with one end of each screw rotatably connected to the sliding crossbeam via a flange, and the other end connected to the lifting mechanism. Two lifting mechanisms are arranged corresponding to the screws, and the motor drives the two lifting mechanisms via a drive shaft. The base is fixedly installed on the top of the rectangular lattice frame, and the lifting mechanism and motor are fixedly installed on the base. The limiting sliding rail is integrated into the inner side of the rectangular lattice frame and forms a sliding pair with the slider at the end of the sliding crossbeam. The array of positioning holes is evenly distributed along the height direction of the rectangular lattice frame and works with the detachable pin mechanism on the sliding crossbeam to lock the position of the sliding crossbeam.

[0020] Preferably, the base height is lower than the box-shaped bottom beam, and at least two adjustable roller bearing platforms are symmetrically installed on the outside of the base. 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 located between the base frame and the top bearing beam. The top bearing beam moves up and down under the drive of the lifting mechanism, and after being raised, the top bearing beam is at the same height as the box-shaped bottom beam. The roller sets are installed on the adjustable roller bearing platforms and the box-shaped bottom beam, and are multiple sets arranged at equal intervals. Both the top bearing beam and the box-shaped bottom beam are provided with concave slots for installing the roller sets.

[0021] The present invention also discloses a method for conducting loading tests using the aforementioned multi-purpose loading test device for the cable system substructure of long-span bridges. This method is applicable to individual tensioning of the main cable model or suspension cable model of a suspension bridge, composite tensioning of the main cable and suspension cable model at any angle, arbitrary-angle suspension tensioning of the cable-stayed bridge model, and vertical tensioning tests of the suspension cable model of a cable-stayed arch bridge. The method includes the following steps:

[0022] S1. Select or fabricate a cable model based on the cable system required for the test;

[0023] S2. Evenly attach several strain gauges to the stressed steel wire in any cross section of the cable model;

[0024] S3, self-balancing reaction frame of assembled cable system;

[0025] S4. Simultaneously lower the sliding crossbeams on both sides to the base reference plane using the electric lifting and locking system for the crossbeams; install the roller support transmission system.

[0026] S5. Install the cable model onto the cable system's self-balancing reaction frame;

[0027] The installation method for a single main cable model or a cable-stayed model is as follows: First, a first through-hole jack is embedded and fixed inside the composite anchor ring of the free-rotation force boundary subsystem, and a force sensor is installed at the front end of the first through-hole jack; a primary anchorage is installed at the loading end of the model, and after the extension wire bundle passes through the primary anchorage, an anchor stress gauge is installed on each strand; an anchorage is installed at the anchorage end of the model; then, the model is hoisted to the adjustable roller support platform of the roller support transmission system, the loading end of the model is oriented to the side of the free-rotation anchorage subsystem, the model is pulled, and with the assistance of multiple roller groups, the loading end of the model passes through the composite anchor ring of the free-rotation anchorage subsystem and the first through-hole jack in the free-rotation force boundary subsystem in sequence, and the secondary anchorage is installed at the loading end through the extension wire bundle of the loading end passing through the first through-hole jack; next, the electric lifting and locking system of the crossbeam is activated to raise the sliding crossbeam to any preset height, and the height of the sliding crossbeam is adjusted to suspend and tension the model at any angle; finally, the roller support transmission system is removed.

[0028] The installation method for a single sling model is as follows: First, a second through-type jack is embedded in the cavity inside the box girder, 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 for fixing the upper end of the sling model; next, the sling model and the main cable model are connected by cable clamps, and an anchor stress gauge and a sling loading end anchor are installed at the loading end of the sling model; finally, the sling loading end anchor extends into the second through-type jack and is locked by a locking anchoring mechanism.

[0029] The installation method for the main cable and sling composite model is as follows: Install the main cable model and sling model in sequence according to the installation method of the main cable model and sling model, and adjust the height of the sliding crossbeam and the horizontal position of the second through-type jack to perform joint tensioning of the main cable and sling composite model at any angle;

[0030] S6. Install displacement gauges on the cable model;

[0031] S7. Control the corresponding through-hole jack to load in stages according to the displacement control mode. The load increment of each stage shall not be less than 5% of the design breaking force. After loading until the model stress reaches the minimum breaking force, switch to force control mode and load at 5-10kN per stage until the model breaks.

[0032] S8. The axial force, displacement, and strand stress and strain data of the collected cable model are transmitted to the computer terminal in real time to monitor and draw the strain and stress state of the cable model throughout the process.

[0033] S9. Replace the loading end anchor, anchorage end anchor, and sling loading end anchor to adapt to different cable models and apply different loads and constraints to different cable systems.

[0034] Compared with existing technologies, the advantages of the multi-purpose loading test device and method for cable system substructures of long-span bridges disclosed in this invention are:

[0035] 1. Capable of stress loading on large-scale cable systems with a capacity of thousands of tons: Through physical design such as self-balancing reaction frame, composite anchor ring and variable cross-section force transmission of cable system, the force transmission path and stress capacity of reaction frame are optimized, which overturns the current status of cable system loading capacity of only hundreds of tons and loading diameter of ≤100mm, so that the loading capacity of the entire loading system can be increased to thousands of tons and the loading diameter can be increased to over 500mm.

[0036] 2. Restore the force boundary of the real cable service period: The free rotation force boundary subsystem and the free rotation anchoring subsystem rotate freely in the sliding beam through the variable cross section force transmission main shaft. With the free sliding of the sliding beam, the cable loading multi-scenario simulation can be realized: (1) suspension tensioning at any angle when the main cable or cable is loaded alone; (2) suspension and multi-directional composite tensioning at any angle of the main cable and cable composite model; (3) vertical tensioning under the real boundary of the cable.

[0037] 3. Versatility and Adaptability: The testing device is suitable for various cable systems, such as suspension bridge cable systems, cable-stayed bridge cable systems, and cable-stayed arch bridge cable systems. It can simulate mechanical behavior under different working conditions, improving the versatility of the testing device. Simultaneously, the modular design allows for rapid assembly and adjustment of components such as the electric lifting and locking system for the crossbeam and the roller support transmission system according to testing requirements. This improves testing efficiency, reduces the cost of repeated purchases and assembly of testing equipment, and enhances the utilization rate of testing resources.

[0038] 4. Ease of Operation and Testing Efficiency: The electric lifting and locking system for the crossbeam achieves synchronous and smooth lifting of the sliding crossbeam through screw linkage, and high-precision positioning and locking are achieved through limit sliding rails and arrayed positioning holes, improving the ease of operation and the stability of testing. By changing the anchors to adapt to different cable system models, test conditions can be quickly switched, allowing for multiple tests and improving testing efficiency.

[0039] 5. Safety and Reliability: The loading-end anchorage, anchorage-end anchorage, and sling loading-end anchorage all adopt a self-locking nonlinear anchoring method, ensuring the stability and safety of the cable model during the loading process. Simultaneously, a through-hole jack is used to achieve staged loading and high-precision force control, ensuring the smoothness and safety of the test process and avoiding test failure due to excessively rapid loading.

[0040] 6. Support for bridge engineering design and evaluation: Through multiple tests and data processing, strain and stress curves of the cable system, both locally and globally, can be generated. The damage evolution law of the cable system from stress to failure under different working conditions can be determined, providing strong support for bridge design optimization and safety assessment. This solves the problems of insufficient equipment bearing capacity, limited model size, and stress concentration in the anchorage area in traditional test methods. It breaks through the size and load limitations of traditional tests and truly restores the stress scenario of the entire bridge.

[0041] 7. High-precision and multi-dimensional monitoring: Integrating cable axial displacement, single-strand cable strain, and stress monitoring, it can simultaneously acquire high-precision data, forming a multi-parameter collaborative monitoring system that comprehensively reflects the mechanical properties of the cable system. Through high-precision sensors and data acquisition systems, the accuracy and reliability of experimental data are ensured, providing high-quality data support for subsequent analysis. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0044] Figure 2 This is a structural schematic diagram of the electric lifting and locking system for the crossbeam provided by the present invention.

[0045] Figure 3 This is a schematic diagram of the adjustable roller bearing platform provided by the present invention.

[0046] Figure 4 This is a schematic diagram of the composite anchor ring and variable cross-section force transmission spindle provided by the present invention.

[0047] Figure 5 This is a schematic diagram of the structure of the cable force loading anchoring subsystem provided by the present invention.

[0048] Figure 6This is a schematic diagram of the free rotation force boundary subsystem provided by the present invention.

[0049] Figure 7 This is a schematic diagram of the composite model of the main cable and suspension cable provided by the present invention.

[0050] In the picture:

[0051] 1-Electric lifting and locking system for the crossbeam; 2-Roller support and transmission system; 3-Composite model of main cable and sling; 4-Self-balancing reaction frame of cable system; 5-Free rotation force boundary subsystem; 6-Free rotation anchoring subsystem; 7-Sling force loading anchoring subsystem;

[0052] 11-Limit sliding rail; 12-Array-type positioning hole group; 13-Screw linkage synchronous lifting subsystem; 131-Base; 132-Screw; 133-Motor; 134-Drive shaft; 135-Reducer; 136-Lifting machine;

[0053] 21-Adjustable roller support platform; 22-Roller assembly; 211-Base frame; 212-Top support beam; 213-Lifting rod; 214-Knob; 215-Support column; 23-Concave slot;

[0054] 31-Main cable model; 311-Strand; 312-First steel wire; 313-Second steel wire; 32-Suspension cable model; 33-Cable clamp;

[0055] 41-Main crossbeam; 42-Column; 43-Fixing hole; 44-Upper crossbeam; 45-Base; 46-Box-type bottom beam; 47-Sliding crossbeam; 48-Fixing seat;

[0056] 51-Composite anchor ring; 52-Four-sided frustum force transmission section; 53-Cylindrical rotating section; 54-First through-hole jack; 55-Primary anchor at loading end; 56-Secondary anchor at loading end;

[0057] 61-Anchorage at the anchorage end;

[0058] 71-Second through-type jack; 72-T-shaped slide rail; 73-Slide rail limiter; 74-Sling loading end anchor; 75-Separable semi-ring assembly; 76-Pulley. Detailed Implementation

[0059] The specific embodiments of the present invention will be briefly described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0060] Figures 1-7A preferred embodiment of the present invention is shown and analyzed in detail.

[0061] like Figure 1 The multi-purpose loading test apparatus for cable-stayed bridge substructures shown is suitable for multi-purpose loading tests on cable-stayed substructures with tonnages of 800-1000t and dimensions of 500-600mm. The apparatus includes a cable-stayed system stress loading system, an electric lifting and locking system 1 for the crossbeam, and a roller support and transmission system 2.

[0062] 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.

[0063] The cable system self-balancing reaction frame 4 includes two sets of symmetrically arranged rectangular lattice frames. Each set of rectangular lattice frames includes four steel box columns 42, arranged in a rectangular pattern, with supports between adjacent columns 42. A top crossbeam 44 is bolted to the top of each column 42. The tops of the two sets of rectangular lattice frames are connected by two main crossbeams 41. Both sets of rectangular lattice frames have an integral base 45 formed by a box-shaped steel platform at their bottom. The two bases 45 are connected by a box-shaped bottom beam 46, with the height of the base 45 lower than that of the box-shaped bottom beam 46. A sliding crossbeam 47 is provided in the middle of each set of rectangular lattice frames. The sliding crossbeam 47 can slide freely and lock in the height direction within the rectangular lattice frame under the drive of the electric lifting and locking system 1.

[0064] 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 stay cable model. Both the free-rotation force boundary subsystem 5 and the free-rotation anchoring subsystem 6 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. Variable cross-section force-transmitting spindles are fixedly installed on both sides of the composite anchor ring 51. The variable cross-section force-transmitting spindles include a truncated square force-transmitting section 52 welded to the composite anchor ring 51 and a cylindrical rotating section 53 welded to the truncated square force-transmitting section 52. Radial stiffening ribs are evenly distributed on the outer surface of the truncated square force-transmitting section 52. The cylindrical rotating section 53 passes through the sliding beam 47 and rotates freely within the sliding beam 47 around the axis of the cylindrical rotating section 53 via a sleeve or bearing structure. This causes the composite anchor ring 51 to rotate freely within the sliding beam 47. Combined with the free sliding of the sliding beam 47, this allows for suspension tensioning at any angle during cable model loading. Both the free rotation force boundary subsystem 5 and the free rotation anchoring subsystem 6 employ variable cross-section force-transmitting spindles and the composite anchor ring 51 design, enabling free rotation and anchoring of the cable model during loading, simulating the mechanical behavior under actual working conditions. The design of the variable cross-section force transmission spindle enables it to adaptively transmit force during loading, improving the flexibility and adaptability of the test device.

[0065] like Figure 6 As shown, the free-rotation force boundary subsystem 5 also includes a first through-hole jack 54 and a loading-end dual-gradient anchoring unit. The first through-hole jack 54 is fixedly installed in the circular through-hole inside the composite anchor ring 51 via a flange, and the inner diameter of the circular through-hole matches the outer diameter of the first through-hole jack 54. The loading-end dual-gradient anchoring unit includes a loading-end primary anchor 55 and a loading-end secondary anchor 56, which are respectively located on both sides of the first through-hole jack 54 to anchor the main cable model 31 or the cable-stayed 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, and 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 stay cable model extends outward through the primary anchor 55 at the loading end, passes through the inner cavity of the first through-hole jack 54, and is finally anchored by the secondary anchor 56 at the loading end. The first through-hole jack 54 pushes the secondary anchor 56 at the loading end to achieve axial force loading of the main cable model 31 or the stay cable model. During the loading process, the variable cross-section force transmission shaft can rotate freely around its axis. The design of the dual-level gradient anchoring unit at the loading end, through the synergistic effect of the primary anchor 55 and the secondary anchor 56 at the loading end, improves the reliability and safety of the anchoring. The first through-hole jack 54 pushes the secondary anchor 56 at the loading end to achieve axial force loading of the main cable model 31 or the stay cable model, which can precisely control the magnitude of the loading force and ensure the accuracy of the test.

[0066] The free-rotating anchoring subsystem 6 also includes an anchoring end anchor 61 to anchor the main cable model 31 or the stay cable model anchoring end. 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.

[0067] like Figure 5 As shown, the cable force loading and anchoring subsystem 7 includes a second through-type jack 71, a cable loading end anchor 74, a locking and 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-shaped bottom beam 46, and the cable loading end anchor 74 is anchored to the end of the cable model 32. The inner diameter of the second through-type jack 71 is 1.1-1.2 times the outer diameter of the cable loading end anchor 74. The locking and anchoring mechanism is located between the second through-type jack 71 and the cable loading end anchor 74. Its inner diameter is equal to the diameter of the cable model 32, and its outer diameter is larger than the outer diameter of the second through-type jack 71. The locking and anchoring mechanism enables the self-locking and release of the cable model 32, ensuring the stability of the cable model 32 during loading and rapid release after unloading.

[0068] The locking and anchoring mechanism is a separable semi-ring assembly 75 connected by a lever 76 and located inside the box-shaped bottom beam 46. The lever 76 drives the separable semi-ring assembly 75 to open and close radially, achieving a two-way function of release and self-locking. After the sling loading end anchor 74 anchors the sling model 32, it passes entirely through the second through-hole jack 71. By moving the levers 76 on both sides of the opening above the box-shaped bottom beam 46, the separable semi-ring assembly 75 is closed. The annular locking surface formed by the separable semi-ring assembly 75 is engaged between the sling loading end anchor 74 and the second through-hole jack 71, preventing the loading end of the sling model 32 from being pulled out from inside the second through-hole jack 71. The second through-hole jack 71 can then load the sling model 32. By moving the lever 76 in the opposite direction, the separable semi-ring assembly 75 is separated, the loading end of the sling model 32 is released, and the sling model 32 can be freely pulled away axially. The locking and anchoring mechanism, driven by lever 76, radially opens and closes the separable semi-ring assembly 75, achieving a two-way function of releasing and self-locking the sling model 32, thus improving the reliability of the sling model 32's anchoring and the flexibility of its operation. This locking and anchoring mechanism design makes the replacement and adaptation of the sling model 32 more convenient, improving the versatility of the testing apparatus. In practice, the locking and anchoring mechanism can be manually opened and closed by entering the box-shaped bottom beam 46. When the separable semi-ring assembly 75 in the locking and anchoring mechanism is closed, it is connected and fixed by a conventional snap-fit ​​device located between the two.

[0069] The T-shaped slide rail 72 is fixedly installed on the box-shaped bottom beam 46. Two slide rail limiters 73 are provided, symmetrically installed at both ends of the T-shaped slide rail 72. The slide rail limiters 73 can move on the T-shaped slide rail 72 and are 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 T-shaped slide rail 72 and the slide rail limiters 73 facilitate the adjustment and fixation of the second through-type jack 71, improving the stability of the sling model 32 under load and the ease of operation. 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.

[0070] The primary anchor 55, secondary anchor 56, anchorage anchor 61, and cable loading anchor 74 have the same structure, all including an anchor ring and a conical clamp assembly. The anchor ring has several conical through holes evenly distributed circumferentially. The conical clamp assembly consists of two equally divided clamps forming a complete conical ring. The outer conical surface of the clamp matches the inner conical surface of the conical through hole in the anchor ring, and the inner wall of the clamp has a spiral friction groove. The stressed steel wire in the cable model passes through the conical clamp assembly and the conical through hole in the anchor ring. During loading, the stressed steel wire moves the conical clamp assembly towards the smaller end of the conical through hole. The clamps are radially compressed and pressed against the conical through hole on the anchor ring. The spiral friction groove forms a mechanical engagement with the surface of the stressed steel wire. Through the synergistic effect of the anchor ring and the conical clamp assembly, self-locking nonlinear anchoring of the stressed steel wire is achieved, improving the safety and reliability of the test.

[0071] like Figure 2 As shown, the electric lifting and locking system 1 for the crossbeam 47 has two sets. Each set of the electric lifting and locking system 1 includes a screw-linked synchronous lifting subsystem 13, a limiting sliding rail 11, and an array of positioning holes 12. The screw-linked synchronous lifting subsystem 13 includes a screw 132, a lifting mechanism 136, a motor 133, and a base 131. Two screws 132 are symmetrically arranged. One end of each screw 132 is rotatably connected to the sliding crossbeam 47 via a flange, and the other end is connected to the lifting mechanism 136. Two lifting mechanisms 136 are arranged corresponding to the screws 132. The motor 133 links the two lifting mechanisms 136 via a drive shaft 134 to control the smooth lifting and lowering of the sliding crossbeam 47. Specifically, the output end of motor 133 is connected to reducer 135, transmitting power to reducer 135. The output ends of reducer 135 are connected to turbine boxes in two lifting machines 136 via two drive shafts 134. The rotation of motor 133 drives turbine boxes to drive lead screw 132 in linear motion, thereby driving the sliding beam 47 to rise and fall smoothly, improving the stability and ease of operation of the test device. Base 131 is fixedly installed on the top beam 44 of the rectangular lattice frame, and lifting machines 136 and motor 133 are fixedly installed on base 131. Limiting sliding rail 11 is integrated inside the column 42 in the rectangular lattice frame, with a T-shaped cross-section, forming a sliding pair with the slider at the end of the sliding beam 47. An array of positioning holes 12 is distributed at equal intervals of 50-100mm along the height of the column 42. A fixing seat 48 is fixedly installed on the sliding beam 47. The fixing seat 48 is provided with fixing holes 43 that cooperate with the array of positioning holes 12 for positioning. A detachable pin mechanism is installed in the fixing hole 43. The array of positioning holes 12, together with the detachable pin mechanism, locks the position of the sliding beam 47. The combined use of the limiting sliding rail 11 and the array of positioning holes 12 can precisely control the position of the sliding beam 47, and the position is locked by the detachable pin mechanism, ensuring the stability of the device during the test.

[0072] The roller support transmission system 2 includes an adjustable roller support platform 21 and a roller assembly 22. For example... Figure 3 As shown, two adjustable roller support platforms 21 are provided, symmetrically installed on the outside of two bases 45. Each adjustable roller support platform 21 includes a base frame 211, a lifting mechanism, and a top support beam 212. The base frame 211 is fixed to the ground by bolts. The lifting mechanism is located between the base frame 211 and the top support beam 212 to drive the top support beam 212 to move up and down. After being lifted by the lifting mechanism, the top support beam 212 is at the same height as the box-shaped bottom beam 46. The lifting mechanism can be any existing technology capable of achieving this function. In this embodiment, the lifting mechanism includes four sets of support columns 215 and lifting rods 213, respectively located at the four corners of the base frame 211. The support columns 215 are rectangular steel columns, fixedly installed on the base frame 211, and are hollow inside. The lifting rods 213 are racks, with one end located inside the column and the other end fixedly connected to the top bearing beam 212. The column also has gears that mesh with the rack for transmission. The surface of the support columns 215 is provided with a knob 214 for driving the gears. Rotating the knob 214 can raise or lower the top bearing beam 212. The roller group 22 is hourglass-shaped and installed on the adjustable roller bearing platform 21 and the box-shaped bottom beam 46. It consists of multiple groups arranged equidistantly along the length of the main cable model 31, with each roller group 22 including two rollers. Both the top supporting beam 212 and the box-shaped bottom beam 46 are equipped with concave grooves 23 for mounting the roller assembly 22, and the width of the concave grooves 23 matches the roller shaft diameter. The hourglass-shaped roller assembly 22 is designed to stably support and transmit the cable model, ensuring the smooth movement of the cable model during the test.

[0073] A method for conducting loading tests using the aforementioned multi-purpose loading test device for the cable system substructure of a long-span bridge is applicable to the individual tensioning of the main cable model 31 or the suspender model 32 of a suspension bridge, the composite tensioning of the main cable and suspender model 3 at any angle, the suspension tensioning of the cable-stayed bridge cable model at any angle, and the vertical tensioning test of the suspender model 32 of a cable-stayed arch bridge.

[0074] The test method specifically includes the following steps:

[0075] S1. Select or fabricate a cable model based on the cable system required for the test. The main cable model 31 or the stay cable model consists of multiple strands 311 of the same diameter and length. Non-stressed first steel wires 312 are evenly and densely filled between each strand 311, with a filling rate controlled at 60-70%. Second steel wires 313 are wound around the outer surface of the model to form a complete main cable model 31 or stay cable model, thus achieving a 1:1 reproduction of the model's weight during actual engineering service. The sling model 32 directly uses real slings and does not require additional fabrication.

[0076] S2. Several strain gauges are evenly attached to the stressed steel wire in any cross section of the cable model to monitor the strain change of the stressed steel wire during the tensioning process, thereby judging the overall stress situation and uniformity of the cable model.

[0077] S3, self-balancing reaction frame of assembled cable system 4.

[0078] S4. The sliding crossbeams 47 on both sides are simultaneously lowered to the reference surface of the base 45 by the electric lifting and locking system 1; the roller support transmission system 2 is installed, and the top support beam 212 on the adjustable roller support platform 21 is raised to the same height as the box-type bottom beam 46.

[0079] S5. Install the cable model onto the cable system self-balancing reaction frame 4:

[0080] The installation method for the single main cable model 31 or the cable-stayed model is as follows: First, a first through-hole jack 54 is embedded and fixed inside 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, and the force sensor is connected to a load display recorder to monitor the magnitude of 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 cable-stayed model. After the cable strands 311 pass through the loading end primary anchor 55, an anchor stress gauge is installed on each cable strand 311 to monitor the stress change of each cable strand 311 of the main cable model 31 or the cable-stayed model during the test. An anchor end anchor 61 is installed at the anchoring end of the main cable model 31 or the cable-stayed model. Then, 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 to the side of the free rotation anchoring subsystem 6. The main cable model 31 or the stay cable model is pulled, and with the assistance of multiple roller groups 22, the loading end of the main cable model 31 or the stay cable model passes sequentially through the composite anchor ring 51 of the free rotation anchoring subsystem 6 and the first through-hole jack 54 in the free rotation force boundary subsystem 5. The loading end cable strand 311 passes through the first through-hole jack 54 to install the loading end secondary anchor 56. Next, the electric lifting and locking system 1 of the crossbeam is activated to raise the sliding crossbeam 47 to any preset height, and the height of the sliding crossbeam 47 is adjusted to perform suspension tensioning of the main cable model 31 or the stay cable model at any angle. Finally, the roller support transmission system 2 is removed.

[0081] The installation method of the single sling model 32 is as follows: First, a second through-type jack 71 is embedded in the cavity inside the box-shaped 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 magnitude of the axial force applied by the second through-type jack 71. Then, a main cable model 31 is installed as a loading auxiliary for fixing the upper end of the sling model 32, following the installation method of the main cable model 31. Since the main cable model 31 is only an auxiliary for the sling model 32, its stress condition is not a concern, so the force sensor at the front end of the first through-type jack 54 and the strain gauge and anchor stress gauge on the main cable model 31 can be omitted. Next, the sling model 32 and the main cable model 31 are connected by a cable clamp 33, and an anchor stress gauge and a sling loading end anchor 74 are installed at the loading end of the sling model 32. Finally, the sling loading end anchor 74 extends into the second through-type jack 71 and is locked by a locking anchoring mechanism.

[0082] like Figure 7 The installation method of the main cable and sling composite model 3 shown is as follows: Install the main cable model 31 and sling model 32 in sequence according to the installation method of the main cable model 31 and 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.

[0083] S6. Install displacement gauges at preset positions on the cable model, such as the mid-span of the main cable model 31 or the end of the suspension cable model 32.

[0084] S7. According to the test requirements, control the corresponding through-hole jacks to load in stages according to the displacement control mode. When testing a single main cable model 31 or a stay cable model, control the loading of the first through-hole jack 54; when testing a single sling model 32, control the loading of the second through-hole jack 71; when testing a composite model 3 of main cable and sling, control the loading of the first through-hole jack 54 and the second through-hole jack 71. The load increment for each stage is 5% of the design breaking force. After loading until the model stress reaches the minimum breaking force, switch to force control mode and load at 5-10kN per stage until the model breaks.

[0085] S8. The axial force, displacement, and stress-strain data of the collected 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.

[0086] S9. Replace the loading end anchor, anchorage end anchor 61 and sling loading end anchor 74 to adapt to different cable models and apply different loads and constraints to different cable systems.

[0087] The above description of the disclosed embodiments enables those skilled in the art to make and use the 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-purpose loading test device for substructures of cable-stayed bridges, characterized in that, This includes a cable system stress loading system, a crossbeam electric lifting and locking system, and a roller support and 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 cable system self-balancing reaction frame includes two sets of symmetrically arranged rectangular lattice frames. Each set of rectangular lattice frames has a base at its bottom, and the two bases are connected by a box-shaped bottom beam. The height of the base is lower than that of the box-shaped bottom beam. The tops of the two sets of rectangular lattice frames are connected by a main crossbeam. Each set of rectangular lattice frames has a sliding crossbeam in its middle section, which can slide freely and lock along the height direction of the rectangular lattice frame. Both the free-rotation force boundary subsystem and the free-rotation anchoring subsystem include a composite anchor ring, which is installed inside a sliding beam and rotates freely within the beam. This, combined with the free sliding of the beam, enables suspension tensioning at any angle during cable model loading. Variable cross-section force transmission shafts are fixedly installed on both sides of the composite anchor ring. Each shaft includes a frustum force transmission section fixedly connected to the composite anchor ring and a cylindrical rotating section fixedly connected to the frustum force transmission section. The cylindrical rotating section passes through the sliding beam and rotates freely within it. The free-rotation force boundary subsystem also includes a first through-hole jack and a loading-end dual-gradient anchoring unit. The first through-hole jack is fixedly installed inside the composite anchor ring. The loading-end dual-gradient anchoring unit includes a primary loading-end anchor and a secondary loading-end anchor, located on either side of the first through-hole jack. The free-rotation anchoring subsystem also includes anchoring end anchors. The cable force loading and anchoring subsystem includes a second through-type jack, a cable loading end anchor, and a locking and anchoring mechanism. The second through-type jack is embedded in the internal cavity of the box-shaped bottom beam. The cable loading end anchor is anchored to the end of the cable model, and its outer diameter is smaller than the inner diameter of the second through-type jack. The locking and anchoring mechanism is located 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, while its outer diameter is larger than the outer diameter of the second through-type jack. The cable force loading and 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-shaped 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. The electric lifting and locking system for the crossbeam has two sets corresponding to the sliding crossbeam. Each set includes a screw-driven synchronous lifting subsystem, a limiting sliding rail, and an array of positioning holes. The screw-driven synchronous lifting subsystem includes a screw, a lifting mechanism, a motor, and a base. Two screws are symmetrically arranged, with one end of each screw rotatably connected to the sliding crossbeam via a flange, and the other end connected to the lifting mechanism. Two lifting mechanisms are corresponding to the screws, and the motor drives the two lifting mechanisms via a drive shaft. The base is fixedly installed on the top of the rectangular lattice frame, and the lifting mechanism and motor are fixedly installed on the base. The limiting sliding rail is integrated inside the rectangular lattice frame and forms a sliding pair with the slider at the end of the sliding crossbeam. The array of positioning holes is evenly distributed along the height direction of the rectangular lattice frame and works with the detachable pin mechanism on the sliding crossbeam to lock the position of the sliding crossbeam. The roller support transmission system includes an adjustable roller support platform and roller sets; the adjustable roller support platform consists of at least two symmetrically installed on the outside of the base, each of which includes a base frame, a lifting mechanism, and a top support beam; the base frame is installed on the ground, the lifting mechanism is located between the base frame and the top support beam, and the top support beam moves up and down under the drive of the lifting mechanism, and after being raised, the top support beam is at the same height as the box-shaped bottom beam; the roller sets are installed on the adjustable roller support platform and the box-shaped bottom beam, and are multiple sets arranged at equal intervals, and both the top support beam and the box-shaped bottom beam are provided with concave slots for installing the roller sets.

2. A method for conducting loading tests using the multi-purpose loading test apparatus for the substructure of a long-span bridge cable system as described in claim 1, characterized in that, This method is applicable to individual tensioning of the main cable model or suspender cable model of a suspension bridge, composite tensioning of the main cable and suspender cable model at any angle, arbitrary-angle suspension tensioning of the cable-stayed bridge model, and vertical tensioning tests of the suspender cable model of a suspension arch bridge; the method includes the following steps: S1. Select or fabricate a cable model based on the cable system required for the test; S2. Evenly attach several strain gauges to the stressed steel wire in any cross section of the cable model; S3, self-balancing reaction frame of assembled cable system; S4. Simultaneously lower the sliding crossbeams on both sides to the base reference plane using the electric lifting and locking system for the crossbeams; install the roller support transmission system. S5. Install the cable model onto the cable system's self-balancing reaction frame; The installation method for a single main cable model or a cable-stayed model is as follows: First, a first through-hole jack is embedded and fixed inside the composite anchor ring of the free-rotation force boundary subsystem, and a force sensor is installed at the front end of the first through-hole jack; a primary anchorage is installed at the loading end of the model, and after the extension wire bundle passes through the primary anchorage, an anchor stress gauge is installed on each strand; an anchorage is installed at the anchorage end of the model; then, the model is hoisted to the adjustable roller support platform of the roller support transmission system, the loading end of the model is oriented to the side of the free-rotation anchorage subsystem, the model is pulled, and with the assistance of multiple roller groups, the loading end of the model passes through the composite anchor ring of the free-rotation anchorage subsystem and the first through-hole jack in the free-rotation force boundary subsystem in sequence, and the secondary anchorage is installed at the loading end through the extension wire bundle of the loading end passing through the first through-hole jack; next, the electric lifting and locking system of the crossbeam is activated to raise the sliding crossbeam to any preset height, and the height of the sliding crossbeam is adjusted to suspend and tension the model at any angle; finally, the roller support transmission system is removed. The installation method for a single sling model is as follows: First, a second through-type jack is embedded in the cavity inside the box girder, 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 for fixing the upper end of the sling model; next, the sling model and the main cable model are connected by cable clamps, and an anchor stress gauge and a sling loading end anchor are installed at the loading end of the sling model; finally, the sling loading end anchor extends into the second through-type jack and is locked by a locking anchoring mechanism. The installation method for the main cable and sling composite model is as follows: Install the main cable model and sling model in sequence according to the installation method of the main cable model and sling model, and adjust the height of the sliding crossbeam and the horizontal position of the second through-type jack to perform joint tensioning of the main cable and sling composite model at any angle; S6. Install displacement gauges on the cable model; S7. Control the corresponding through-hole jack to load in stages according to the displacement control mode. The load increment of each stage shall not be less than 5% of the design breaking force. After loading until the model stress reaches the minimum breaking force, switch to force control mode and load at 5-10kN per stage until the model breaks. S8. The axial force, displacement, and strand stress and strain data of the collected cable model are transmitted to the computer terminal in real time to monitor and draw the strain and stress state of the cable model throughout the process. S9. Replace the loading end anchor, anchorage 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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