Large-span arch bridge main arch ring large-scale model test loading system

Abstract

The application discloses a large-span arch bridge main arch ring large-scale model test loading system and relates to the technical field of civil engineering tests, which comprises a main arch ring, the material strength and stress state of the main arch ring are consistent with those of an actual bridge; loading points are uniformly arranged on the main arch ring according to the actual available space in a laboratory, the operation feasibility and the finite element test results; a main arch ring fixing tool is installed on the loading points; a connecting rod is installed on the lower surface of the main arch ring fixing tool; the lower end of the connecting rod is connected with the upper end of a pulley block loading assembly; the lower end of the pulley block loading assembly is hinged with the upper surface of a lower tool; and the lower tool is fixedly connected with the ground. The large-span arch bridge main arch ring large-scale model test loading system has the advantages of strong universality, reusability, low cost, safe operation, smooth force transmission, small loss, accurate load transmission and the capability of meeting the loading requirements of multiple working conditions.

Description

Technical Field

[0001] This invention relates to the field of civil engineering testing technology, and in particular to a large-scale scale model testing loading system for the main arch ring of an ultra-long span arch bridge. Background Technology

[0002] Scaled-down model testing, as an effective method for obtaining the true structural state of bridges under load conditions, has been applied in many large bridges both domestically and internationally, such as the Chongqing Wanxian Yangtze River Bridge, the Beipanjiang Grand Bridge of the Shanghai-Kunming High-Speed ​​Railway, and the Wushan Daning River Double-Track Bridge of the Zhengzhou-Wanzhou High-Speed ​​Railway. These scaled-down tests have provided effective theoretical and technical support for the safe construction and operation of bridges.

[0003] Currently, research on bridge scale-down test design by scholars both domestically and internationally mainly focuses on two aspects: feasibility verification of bridge construction schemes and analysis of the static and dynamic performance of the structure after completion. The former primarily involves simulating the bridge construction process through scale-down model tests, collecting deformation and stress data of the structure during construction to verify the feasibility of the construction scheme. For example, Zhang Shuangyang et al. designed a 1:7.5 scale-down model test for the main arch ring of the Beipanjiang Grand Bridge on the Shanghai-Kunming High-Speed ​​Railway, with a main span of 445m. However, due to time constraints, this scale-down test eliminated the division of the outer concrete working surface and working sections. Tang Xiaobo et al. conducted a 1:10 scale-down model test for the main arch ring of the Wanzhou Yangtze River Bridge, with a main span of 420m, to study the feasibility of the main arch ring forming sequence and the internal forces and deformations of the main arch during the construction stage. This test used 27 sets of lever devices to counterweight the main arch ring, and the vertical deflection at the loading point was measured. Changing the load at adjacent loading points increases the workload of counterweighting, and the accuracy of counterweighting at each loading point is difficult to guarantee. The latter focuses more on the static and dynamic performance of the structure after the bridge is completed. For example, in order to test the dynamic characteristics of a large-span irregular steel-concrete arch bridge, a 1:16 scale model test was designed for the Yitong River Bridge with a main span of 158m. Iron bricks were used to simulate moving loads, but due to space limitations, it was difficult to achieve an equivalent counterweight for the self-weight load. Liu Zengwu et al. conducted a 1:16 scale test on the main arch ring of the Washiwo Bridge with a clear span of 95m to study the failure mode of the catenary arch under the conditions of arch crown loading and L / 4 span loading. However, this single-point loading or two-point symmetrical loading method cannot restore the actual stress form of the bridge.

[0004] In summary, current research still suffers from limitations such as the inability to accurately represent the actual engineering construction process using scaled-down structures and difficulties in loading, especially for ultra-long-span arch bridges where the construction process is more complex and the requirements for loading accuracy and numerical stability are more stringent. Studying the mechanical behavior of stiffened-frame concrete arch bridges during arch formation through scaled-down model tests of the main arch ring requires not only addressing the shortcomings of existing research but also developing a more detailed design for the loading scheme. Summary of the Invention

[0005] The purpose of this invention is to provide a large-scale scaled model test loading system for the main arch ring of an ultra-large span arch bridge, thereby solving the problems listed in the background art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention relates to a large-scale scaled model test loading system for the main arch ring of an ultra-long span arch bridge, comprising a main arch ring whose material strength and stress state are consistent with those of the actual bridge. The main arch ring is uniformly arranged with loading points based on the actual available space in the laboratory, operational feasibility, and finite element calculation results. A main arch ring fixing fixture is installed at the loading point, and a connecting rod is installed on the lower surface of the main arch ring fixing fixture; The lower end of the connecting rod is connected to the upper end of the pulley loading assembly, the lower end of the pulley loading assembly is hinged to the upper surface of the lower tooling, and the lower tooling is fixedly connected to the ground.

[0007] Preferably, a tension sensor is also installed on the connecting rod, which displays and collects the load value at the loading position of the main arch ring in real time.

[0008] Preferably, the pulley block loading assembly includes a movable pulley unit, a fixed pulley unit, and a loading unit, wherein the movable pulley unit is hinged to the connecting rod; The fixed pulley unit is hinged to the lower tooling; The movable pulley unit and the fixed pulley unit are connected through the loading unit.

[0009] Preferably, the movable pulley unit includes pulley S1, pulley S2 and pulley S3, which are arranged sequentially from top to bottom; The fixed pulley unit includes pulley X1, pulley X2 and pulley X3, which are arranged sequentially from top to bottom.

[0010] Preferably, the loading unit includes a wire rope and a counterweight box. One end of the wire rope is fixedly installed on the axis of the S3 pulley, and the other end of the wire rope passes through the X1 pulley, S3 pulley, X2 pulley, S2 pulley, X3 pulley and S1 pulley in a counterclockwise order, and the counterweight box is suspended at the end of the winding.

[0011] Preferably, counterweights are placed inside the counterweight box and loaded in stages according to the test requirements.

[0012] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention relates to a large-scale scale model test loading system for the main arch ring of an ultra-large span arch bridge. The main arch ring fixing fixture is detachably mounted on the loading point of the main arch ring, offering strong versatility and ensuring reusability. Furthermore, the pulley loading assembly adopts a multi-stage pulley system for labor-saving loading, achieving large tonnage, staged, and stable loading with small counterweights. This is cost-effective and safe to operate. At the same time, the design of the moving pulley unit, fixed pulley unit, and wire rope winding is scientific, ensuring smooth force transmission, low loss, and precise load transfer, meeting the loading requirements of multiple working conditions. Additionally, tension sensors are arranged between the connecting rods to collect load data in real time, enabling precise monitoring and control of the loading process and ensuring the accuracy of the data collected during the experiment. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the overall layout of the loading system for the large-scale scale model test of the main arch ring of the super-large span arch bridge of the present invention. Figure 2 This is a partial schematic diagram of the loading system for a large-scale scaled model test of the main arch ring of the super-large span arch bridge of the present invention; Figure 3 This is a partial layout diagram of the pulley block loading assembly of the present invention; Figure 4 This is a schematic diagram illustrating the working principle of the single pulley block loading system of the present invention. Figure 5 This is a loading test time-load curve diagram for the present invention; Figure 6 This is a time-load curve diagram for each loading point in this application.

[0015] Explanation of reference numerals in the attached drawings: 1-Main arch ring fixing fixture; 2-Main arch ring; 3-Connecting rod; 4-Tension sensor; 5-Moving pulley unit; 6-Fixed pulley unit; 7-Counterweight box; 8-Lower fixture. Detailed Implementation

[0016] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] like Figure 1-6 As shown, the large-scale scaled model test loading system of the main arch ring of the super-long span arch bridge includes the main arch ring 2. The main arch ring 2 is designed based on stress equivalence. The overall geometric parameters such as the sag-span and sag-height are converted according to the scaled ratio. The local design is based on the principle of meeting stiffness similarity and structural requirements. The construction process of the outer concrete is to restore the actual project to the greatest extent possible, so as to ensure that the material strength and stress state of the main arch ring 2 are consistent with the actual bridge. The main arch ring 2 is uniformly arranged with loading points based on the actual available space in the laboratory, operational feasibility, and finite element calculation results, which effectively avoids local stress concentration and loading eccentricity, making it easy to install and having good stability. A main arch ring fixing fixture 1 is installed at the loading point. The main arch ring fixing fixture 1 includes parallel steel sections and tie bolts. The tie bolts connect two steel sections to form a rectangular frame with nuts, and the rectangular frame is fitted at the loading point. It is highly versatile and reusable. The lower surface of the upper steel section abuts against the upper surface of the loading point, and a connecting rod 3 is installed on the lower surface of the lower steel section. The lower end of the connecting rod 3 is connected to the upper end of the pulley loading assembly, the lower end of the pulley loading assembly is hinged to the upper surface of the lower tooling 8, and the lower tooling 8 is fixedly connected to the ground.

[0018] Specifically, a tension sensor 4 is also installed on the connecting rod 3, which displays and collects the load value at the loading position of the main arch ring 2 in real time.

[0019] Specifically, the pulley loading assembly includes a movable pulley unit 5, a fixed pulley unit 6, and a loading unit, wherein the movable pulley unit 5 is hinged to the connecting rod 3; The fixed pulley unit 6 is hinged to the lower tooling 8; The movable pulley unit 5 and the fixed pulley unit 5 are connected through the loading unit.

[0020] Specifically, the movable pulley unit 5 includes pulleys S1, S2, and S3, which are arranged sequentially from top to bottom, and the sizes of pulleys S1, S2, and S3 decrease sequentially from top to bottom. The fixed pulley unit 6 includes pulleys X1, X2, and X3, which are arranged sequentially from top to bottom, and the sizes of pulleys X1, X2, and X3 increase sequentially from top to bottom.

[0021] Specifically, the loading unit includes a steel wire rope and a counterweight box 7. One end of the steel wire rope is fixedly installed on the axis of the S3 pulley, and the other end of the steel wire rope passes through the X1 pulley, S3 pulley, X2 pulley, S2 pulley, X3 pulley and S1 pulley in a counterclockwise order, and the counterweight box 7 is suspended at the end of the winding.

[0022] Specifically, counterweights are placed inside the counterweight box 7, and are loaded in stages according to the test requirements.

[0023] Example 1

[0024] The model test was designed according to the principle of stress equivalence. At a scale of 1:10, a counterweight of 9 times the self-weight should be applied to the model arch. The self-weight load is approximately uniformly distributed along the longitudinal direction of the main arch ring. Theoretically, the 9 times counterweight should also be applied as a uniformly distributed load. Considering the actual available space in the laboratory, operational feasibility, and finite element calculation results, a loading point was finally arranged every 2m along the longitudinal direction of the bridge, and the concentrated force at 29 loading points replaced the uniformly distributed load.

[0025] The accuracy of experimental data is directly affected by reasonable and precise counterweighting, making efficient and feasible counterweighting methods a crucial aspect of experimental design. To address the shortcomings of traditional loading methods, a pulley system loading scheme was designed. The working principle of this scheme is as follows: Figure 4 As shown in the diagram, pulleys X1, X2, and X3 form a fixed pulley system, which is fixed to the ground; pulleys S1, S2, and S3 form a movable pulley system, which is connected to the upper structure by an elastic support to simulate the vertical displacement of the main arch ring; the pulley systems are connected by a winding line, with the axis of pulley S3 as the starting point, and the line passes through pulleys X1, S3, X2, S2, X3, and S1 in a counterclockwise order, and a counterweight is suspended at the end of the winding line; The connection between the movable pulley block and the main arch ring is achieved through the main arch ring fixing fixture and connecting rod; the fixed pulley unit 6 and the ground are connected through the lower fixture 8 and the lower fixture fixing seat; the counterweight box 7 is used to place the counterweight blocks, which can be loaded in stages according to the test requirements; the tension sensor 4 can display and collect the load value at the loading position of the main arch ring in real time.

[0026] Based on the experimental requirements, the loading devices from the previous section were sequentially arranged along the longitudinal direction of the bridge to form an array-type pulley loading system. In this system, even if the counterweights at adjacent loading points affect the vertical displacement of the current loading point, the load amplification factor at the current loading point will revert to approximately 7 times over time due to the equal tension of the steel wire ropes on both sides of the same pulley, demonstrating self-balancing characteristics. This system overcomes the drawbacks of the jack loading method (where the loading value is difficult to stabilize over a long period), the lever method (where the loading value is easily affected by adjacent loading points), and the direct counterweight method (where the counterweight block is too large). To verify the reliability and mechanical efficiency of the loading device, a staged loading test was conducted on a single pulley block loading system, such as... Figure 5As shown, in this system, the crossbeams of the portal frame are used instead of the main arch ring. Gradual loading is achieved by continuously placing 40cm×40cm×2cm steel plates into the counterweight box. During the experiment, the loading was divided into four levels, with each level carrying a load of 0.2t, 0.4t, 0.6t, and 0.8t respectively. After loading, the total mass of the counterweight box was 2.0t. By reading real-time data from the tension sensor, the actual amplification factor of the pulley loading system was obtained. After each loading cycle, the load amplification factor of a single pulley loading device takes about 10 minutes to reach a stable state. This is because the steel wire rope needs to overcome the resistance at the pulleys to transfer the tension of the outermost steel wire rope layer by layer to the innermost steel wire rope. This process is called the hysteresis effect, and it is this effect that causes the load amplification factor to suddenly decrease each time loading occurs, as shown at points A, B, C, and D in the figure.

[0027] Furthermore, after each loading stage was completed, the load amplification factor remained relatively stable at around 6.6 times, indicating that the mechanical efficiency of the single pulley loading system was approximately 94.29%, which met the test requirements. Moreover, the influence of friction loss on the loading value could be eliminated by the specific readings of the tension sensor.

[0028] like Figure 6 As shown, approximately 5 minutes after loading is completed at each loading point, the tension sensor values ​​all reach the design load and remain basically stable. Furthermore, the load value at the i-th (i=6,11,15) loading point is affected by the j-th (j=6,11,15,j≠i) loading point. This is because the counterweight of the latter generates a vertical deflection at the former loading position. This deflection is transmitted to the movable pulley system, causing the movable and fixed pulley systems to move closer together, resulting in a certain degree of slack in the wire rope and a reduction in the total load value. However, after approximately 5 minutes, each loading point recovers to its original load because the tension of the wire ropes on both sides of the same pulley is equal. This demonstrates that the self-stabilizing characteristic of the system causes the mutual influence between loading points to disappear over time, proving that the array pulley loading system has good stability and high reliability.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0030] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A large-scale scaled model test loading system for the main arch ring of a super-long span arch bridge, characterized in that: Including the main arch ring (2), the material strength and stress state of the main arch ring (2) are consistent with those of the actual bridge; Loading points are evenly arranged on the main arch ring (2) according to the actual available space of the laboratory, operational feasibility and finite element calculation results; A main arch ring fixing fixture (1) is installed at the loading point, and a connecting rod (3) is installed on the lower surface of the main arch ring fixing fixture (1). The lower end of the connecting rod (3) is connected to the upper end of the pulley loading assembly, the lower end of the pulley loading assembly is hinged to the upper surface of the lower tooling (8), and the lower tooling (8) is fixedly connected to the ground.

2. The large-scale scale model test loading system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that: A tension sensor (4) is also installed on the connecting rod (3). The tension sensor (4) displays and collects the load value at the loading position of the main arch ring (2) in real time.

3. The large-scale scale model test loading system for the main arch ring of a super-long span arch bridge according to claim 2, characterized in that: The pulley loading assembly includes a movable pulley unit (5), a fixed pulley unit (6), and a loading unit. The movable pulley unit (5) is hinged to the connecting rod (3). The fixed pulley unit (6) is hinged to the lower tooling (8); The movable pulley unit (5) and the fixed pulley unit (6) are connected through the loading unit.

4. The large-scale scale model test loading system for the main arch ring of a super-long span arch bridge according to claim 3, characterized in that: The movable pulley unit (5) includes pulley S1, pulley S2 and pulley S3, which are arranged sequentially from top to bottom; The fixed pulley unit (6) includes pulley X1, pulley X2 and pulley X3, which are arranged sequentially from top to bottom.

5. The large-scale scale model test loading system for the main arch ring of a super-long span arch bridge according to claim 4, characterized in that: The loading unit includes a wire rope and a counterweight box (7). One end of the wire rope is fixedly installed on the axis of the S3 pulley. The other end of the wire rope passes through the X1 pulley, S3 pulley, X2 pulley, S2 pulley, X3 pulley and S1 pulley in a counterclockwise order, and the counterweight box (7) is suspended at the end of the winding.

6. The large-scale scale model test loading system for the main arch ring of a super-long span arch bridge according to claim 5, characterized in that: The counterweight box (7) contains counterweight blocks, which are loaded in stages according to the test requirements.

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