A large-span arch bridge main arch ring large-scale model test system and method
By designing a large-scale scaled model test system for the main arch ring of an ultra-long span arch bridge, and combining a self-balancing pulley system and a multi-dimensional test module, the problems of inaccurate simulation and insufficient safety in existing tests were solved. Stress equivalence and accurate data capture were achieved, thus improving the stability and reliability of the test.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING JIAOTONG UNIV
- Filing Date
- 2026-06-04
- Publication Date
- 2026-07-24
AI Technical Summary
Existing scaled-down tests of large-span arch bridges cannot realistically simulate the segmented construction process. Traditional loading methods are unstable, making it difficult to accurately analyze stress evolution. Furthermore, the lack of a suitable limiting and protection system results in insufficient test safety and data reliability.
A large-scale scaled model test system for the main arch ring of an ultra-large span arch bridge was designed, including an array-type self-balancing pulley loading module, a multi-dimensional strain testing module, a multi-source displacement testing module, and a portal-type limit protection module. The model design was carried out in combination with the similarity theory π theorem to achieve uniform load distribution and stress equivalence. Automated counterweight statistics and loading optimization algorithms were adopted to accurately simulate the construction process.
This approach achieves equivalence between the model and the actual bridge stress, accurately captures the laws of mechanical behavior, improves the safety and reliability of the experiment and the data, reduces the amount of manual work, and ensures the stability and accuracy of the experimental process.
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Figure CN122448619A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bridge engineering technology, and more specifically to a large-scale scaled-down model test system and method for the main arch ring of an ultra-long span arch bridge. Background Technology
[0002] With the continuous improvement of transportation infrastructure networks, the construction of bridges in mountainous areas is accelerating. Concrete arch bridges, due to their advantages such as high stiffness, aesthetic appeal, strong adaptability to mountainous terrain, and low maintenance costs, are becoming one of the most competitive bridge types for long-span mountainous bridges. However, when the main arch ring of an arch bridge is constructed using a segmented, ring-by-ring method, the cross-sectional stiffness develops asynchronously with each construction stage, resulting in significant differences in the stress development history of each component, complex and variable time-varying material properties, and a sharp increase in the difficulty of controlling the arch formation state. To address these challenges, it is urgent to further clarify the mechanical behavior of concrete arch bridges during the arch formation process, define the load-bearing mechanisms and stress evolution laws of the stiffening steel frame, the inner concrete, and the outer concrete throughout the entire construction process, clarify the force transmission mechanism between the concrete in each ring and segment, and propose methods for controlling the arch formation state of the main arch ring, providing theoretical support for the development of concrete arch bridges with larger spans.
[0003] Scaled-down model testing is a core method for obtaining the true mechanical response of a bridge under load and verifying the feasibility of construction schemes. However, existing scaled-down tests of large-span arch bridges still have many shortcomings: existing tests often eliminate the division between the outer concrete working surface and the working section, making it impossible to reproduce the actual construction process of the bridge in segments and rings, and difficult to truly simulate the mechanical behavior of the entire arch formation process; traditional loading methods have obvious defects, the lever method loading values are easily affected by the vertical displacement of nearby loading points, the accuracy of counterweights is difficult to guarantee, the jack method cannot achieve long-term stable load maintenance, the direct counterweight method has excessively large counterweight blocks, and single-point / two-point symmetrical loading cannot reproduce the actual stress form of uniformly distributed loads on the actual bridge; existing testing systems cannot fully capture the stress differences between the main arch ring interfaces and between the segments, making it difficult to accurately analyze the impact of concrete age differences on stress evolution, displacement testing methods are limited, data lacks multi-source verification, and reliability is insufficient; large-scale single-rib scaled models have a large slenderness ratio, resulting in a high risk of out-of-plane instability during construction, and the lack of a suitable limiting and protection system makes it difficult to ensure structural safety throughout the test process. Therefore, how to provide a large-scale scaled model test system and method for the main arch ring of an ultra-large span arch bridge is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0004] In view of this, the present invention provides a large-scale scaled model test system and method for the main arch ring of an ultra-large span arch bridge, which solves the problems of existing scaled tests, realizes stress equivalence between the model and the actual bridge, and accurately captures the mechanical behavior law of the arch formation process.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A large-scale scaled-down model test system for the main arch ring of an ultra-long span arch bridge includes a scaled-down model test main structure, an array-type self-balancing pulley loading module, a multi-dimensional strain testing module, a multi-source displacement testing module, and a portal-type limiting protection module. The scaled-down model test main structure is based on the similarity theory π theorem and uses a large-span concrete arch bridge as a prototype. The array-type self-balancing pulley loading module includes multiple single-set pulley loading devices, which are sequentially arranged along the longitudinal direction of the main arch ring of the scaled-down model test main structure to simulate the uniformly distributed load throughout the construction process of the main arch ring. The multi-dimensional strain testing module is located at key sections and interfaces of the main arch ring to collect strain data of the entire cross-section, inter-ring interfaces, and inter-segment interfaces of the main arch ring during the entire construction process. The multi-source displacement testing module is located at key displacement sections of the main arch ring to collect deformation and spatial alignment data of the main arch ring during the entire construction process. The portal-type limiting protection module is spaced along the longitudinal direction of the main arch ring to limit the lateral out-of-plane displacement of the main arch ring.
[0006] Optionally, the scale of the main structure of the scaled model test is 1:10.
[0007] Optionally, the array-type self-balancing pulley block loading module also includes a real-time acquisition device, a counterweight statistics device, and a loading optimization device. The real-time acquisition device is used to acquire the load at each loading point, the counterweight statistics device is used to calculate the theoretical counterweight value at each loading point in different construction stages, and the loading optimization device is used to calculate the counterweight reduction coefficient and actual loading value at each loading point in different construction stages.
[0008] Optionally, a single pulley loading device includes a fixed pulley block, a movable pulley block, a connecting rod, a fixed fixture, a lower fixture, a counterweight box, and a tension sensor. The fixed pulley block contains three fixed pulleys and is fixed to the ground by the lower fixture. The movable pulley block contains three movable pulleys and is connected to the main arch ring by the connecting rod and the fixed fixture. The winding cord passes through the movable pulley block and the fixed pulley block and then connects to the counterweight box at its end. The tension sensor is located at the connecting rod and collects the load values at the corresponding loading point in real time.
[0009] Optionally, the multi-dimensional strain testing module includes a 16-point section strain testing device, an inter-segment interface strain testing device, and a temperature compensation device. The 16-point section strain testing device has 17 strain testing sections evenly arranged along the longitudinal direction of the main arch ring. Each testing section is equipped with 15 fiber optic strain sensors to collect strain data from the concrete of the bottom plate, web, and top plate, as well as the inter-ring interfaces between the bottom plate and web, and between the web and top plate. The inter-segment interface strain testing device has six testing sections, one on each side of the three inter-segment interfaces at the junction of adjacent working faces. Each testing section is equipped with 15 fiber optic strain sensors to collect strain data from the concrete of the top plate, bottom plate, and web. The temperature compensation device has three fiber optic temperature sensors evenly arranged in each strain testing section, embedded inside the concrete of the bottom plate, web, and top plate, to eliminate the influence of ambient temperature and concrete hydration heat on the strain data.
[0010] Optionally, the multi-source displacement testing module includes a wire-type displacement testing device, a total station testing device, and a three-dimensional laser scanning testing device. The wire-type displacement testing device sets up 7 displacement testing sections at the 8th point of the main arch ring, with 4 wire-type displacement sensors deployed in each section. The total station testing device sets up 402 measuring points throughout the arch to supplement and verify the wire-type displacement data. The three-dimensional laser scanning testing device acquires the spatial alignment data of the entire bridge structure of the main arch through multi-site scanning.
[0011] Optionally, a portal frame is arranged every 10m along the longitudinal direction of the main arch ring, for a total of 5 frames; the heights of the portal frames are 9m, 13m, 15m, 13m, and 9m respectively, and the width is 3.6m; the portal frames only restrict the lateral out-of-plane displacement of the main arch ring, and have no constraint on the longitudinal and vertical displacement of the structure.
[0012] A method for testing a large-scale scaled model of the main arch ring of an ultra-long span arch bridge includes the following steps: S1. Based on the similarity theory π theorem, complete the geometric, material, and construction scheme design of a large-scale scaled model using a large-span concrete arch bridge as the prototype; complete the construction of the arch seat, the assembly and closure of the stiffened steel frame, and the pouring of concrete inside the pipe. S2. Install the array-type self-balancing pulley block loading module, and determine the target counterweight value of each loading point in each construction stage through an automated counterweight statistics program and loading optimization algorithm; S3. Deploy multi-dimensional strain testing module and multi-source displacement testing module sensors and complete calibration and data acquisition debugging; S4. Install the portal-type limit protection module along the longitudinal direction of the main arch ring to complete the positioning and fixing; S5. The arching process of the main arch ring is divided into multiple construction stages. Following the principle of first loading the counterweight and then pouring the concrete, the graded loading, data synchronous collection and concrete pouring of each construction stage are completed in sequence until the concrete of the top plate of the main arch ring is closed. S6. Temperature correction is applied to the collected strain data, and multi-source displacement data is fused to analyze the stress evolution law, bearing mechanism and force transmission mechanism of the main arch ring during arch formation.
[0013] Optionally, S2 is as follows: S21. Install a single set of pulley loading devices every 2m along the longitudinal direction of the main arch ring to form an array-type self-balancing loading module, and complete the connection and debugging of the tension sensor, real-time acquisition device, counterweight statistics device and loading optimization device. S22. Conduct a graded loading test on a single pulley group, with graded loading weights of 0.2t, 0.4t, 0.6t, and 0.8t, and calibrate the actual load amplification factor and mechanical efficiency of the device; S23. By importing the finite element model and construction stage division through the automated counterweight statistics program, the theoretical counterweight value of each loading point in each construction stage is automatically calculated. S24. Based on the counterweight reduction coefficient optimization algorithm, distinguish between overall stress and local stress components, calculate the counterweight reduction coefficient of each loading point in each construction stage, and determine the final actual loading value.
[0014] Optionally, the specific algorithm for optimizing the counterweight reduction factor in S24 is as follows: ; In the formula, For the first i In the first construction phase, the... j The weight reduction factor at each loading point The model arch is in the first i In the first construction phase, the... j The sum of the self-weights of the components near each loading point; The model bridge is represented in the first... i In the first construction phase, the... j The sum of the self-weights of the components near each loading point that participate in the overall structural stress; Indicates the first i In the first construction phase, the... j The sum of the self-weights of the components that participate in the local structural stress near the loading point after being scaled down from the actual bridge dimensions.
[0015] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a large-scale scaled model test system and method for the main arch ring of an ultra-large span arch bridge, which has the following beneficial effects: The present invention completes the design of a 1:10 large-scale scaled model based on the similarity theory π theorem, realizing the stress equivalence between the model and the prototype bridge. The segmented concrete outer ring scheme is completely consistent with the prototype bridge, which can accurately reproduce the entire construction process of the actual bridge, solving the problem that existing scaled models cannot realistically simulate the segmented arch mechanical behavior of ultra-large span arch bridges. An array-type self-balancing pulley loading system is designed, which realizes the equivalent simulation of uniformly distributed loads across the entire span through the pulley device. It has self-balancing and self-stabilizing characteristics, which can eliminate the mutual influence caused by the displacement of adjacent loading points. With the help of an automated counterweight statistics program and loading optimization algorithm, the graded loading counterweight calculation for multiple construction stages can be completed efficiently and accurately, greatly reducing the amount of manual work, while ensuring the stress equivalence effect. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of the segmented and ring-shaped concrete pouring method for the main arch ring of the present invention. Figure 2 This is a schematic diagram illustrating the working principle of the single-set pulley loading device of the present invention. Figure 3 This is a schematic diagram of the forces acting on a single pulley according to the present invention; Figure 4 This is a schematic diagram of the arrangement of a single pulley loading device according to the present invention; Figure 5 This is a partial layout drawing of the pulley system of the present invention; Figure 6 This is a schematic diagram of the overall layout of the array-type self-balancing pulley loading module of the present invention; Figure 7 This is a loading test time-load curve diagram of the present invention; Figure 8 This is a time-load curve diagram for each loading point of the present invention; Figure 9 This is a schematic diagram of the strain test cross section and the arrangement of strain measurement points in this invention; Figure 10 This is a schematic diagram showing the longitudinal arrangement of the sensors according to the present invention; Figure 11 This is a schematic diagram showing the arrangement of the measuring points of the inter-segment interface sensor according to the present invention; Figure 12 This is a schematic diagram showing the longitudinal arrangement of the displacement measuring points according to the present invention; Figure 13 This is a schematic diagram comparing the stress results during the construction process of the 1 / 4 span section of the foundation slab concrete of the present invention; Figure 14 This is a schematic diagram comparing the stress results during the construction process of the web concrete 1 / 4 span section of the present invention; Figure 15 This is a flowchart illustrating the statistical process of counterweights at each loading point in this invention. Detailed Implementation
[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0019] This invention discloses a large-scale scaled-down model test system for the main arch ring of an ultra-long span arch bridge, comprising a scaled-down model test main structure, an array-type self-balancing pulley loading module, a multi-dimensional strain testing module, a multi-source displacement testing module, and a portal-type limiting protection module. The scaled-down model test main structure is based on the similarity theory π theorem and uses a large-span concrete arch bridge as a prototype. The array-type self-balancing pulley loading module includes multiple single-set pulley loading devices, which are sequentially arranged along the longitudinal direction of the main arch ring of the scaled-down model test main structure to simulate the uniformly distributed load throughout the construction process of the main arch ring. The multi-dimensional strain testing module is located at key sections and interfaces of the main arch ring to collect strain data of the entire cross-section, inter-ring interfaces, and inter-segment interfaces of the main arch ring during the entire construction process. The multi-source displacement testing module is located at key displacement sections of the main arch ring to collect deformation and spatial alignment data of the main arch ring during the entire construction process. The portal-type limiting protection module is spaced along the longitudinal direction of the main arch ring to restrict the lateral out-of-plane displacement of the main arch ring.
[0020] Furthermore, the scale of the main structure of the scaled-down model test is 1:10.
[0021] In this embodiment of the invention, the actual bridge selected is the Tian'e Longtan Grand Bridge. The Tian'e Longtan Grand Bridge is a top-bearing concrete arch bridge with a calculated span of 600 m, a rise of 125 m, and a rise-to-span ratio of 1 / 4.8. The main arch ring adopts a catenary shape with an arch axis coefficient m=1.9. The arch ribs use a box girder section with constant width and varying height. The box width is 6.5 m, the box height at the arch foot is 12.0 m, and the box height at the arch crown is 8.0 m. The transverse center distance of the arch ribs is 16.5 m. The thickness of the arch box web gradually changes from 0.45 m at the arch crown to 0.95 m at the arch foot, the top plate thickness is 0.65 m, and the bottom plate thickness gradually changes from 65 mm at the arch crown to 1.3 m at the arch foot. The rigid steel frame mainly uses Q420qd25z steel. The internal concrete is C80 self-compacting micro-expansion concrete, and the external concrete is C60 concrete. The external concrete is poured using a segmented ring method, dividing the outer concrete transversely into three rings: bottom plate, web plate, and top plate. Longitudinally, it employs eight working faces, each divided into six segments for pouring. Figure 1 As shown.
[0022] This scaled-down model test adopts stress equivalence as its design principle. Overall geometric parameters such as span and elevation are converted according to the scale ratio. Local design prioritizes stiffness similarity and structural requirements. The concrete encasing process replicates the actual engineering conditions to the greatest extent possible, aiming for consistency between the stress state of the model bridge and the actual bridge. Specifically: 1. Determine the scale ratio for the model test. The scale of a bridge scale-up model test reflects the similarity criteria between the physical parameters of the model arch and the actual bridge. These physical parameters mainly include stress, strain, elastic modulus, geometric dimensions, area, and volume. One of the main tasks and challenges in model design is designing the scale. Using an excessively large scale will place higher demands on the test space and loading equipment; conversely, when a small error occurs in the model test, using a small scale will cause that error to be severely amplified.
[0023] Based on the π theorem of similarity theory, when stress similarity is considered, the following similarity criteria exist between the model bridge and the actual bridge: ; In the formula, Represents a dimensionless parameter. , and These represent stress, displacement, and rotation, respectively. , and q These represent concentrated force, bending moment, and shear force, respectively. , and These represent length, area, and volume, respectively. , , and These represent the material's elastic modulus, moment of inertia at the cross section, strain, and Poisson's ratio, respectively. Stress results are also included. The for Considering that the experimental results are a function of each experimental condition, according to the second theorem of similarity theory, we have: ; It can be seen that, in order to ensure that the stress of the model arch and the actual bridge are similar, the model test should be designed to: ; In the formula, subscripts are used respectively. m and n Distinguish between the parameters of the model arch and the actual bridge, and implement: ; If the ratio of the same physical quantities between the model arch and the actual bridge is defined as a similarity constant, denoted by the symbol... If we express this, then we have: ; The ratio of the geometric dimensions of the model arch and the actual bridge is called the geometric similarity constant or geometric scaling ratio, denoted by the symbol... This means, that is: ; Therefore: ； Once the scale ratio of the model test is determined, the similarity constants such as axial force, bending moment, shear force, area, volume, moment of inertia, and Poisson's ratio between the model arch and the actual bridge can be determined.
[0024] 2. Model test structure design
[0025] This scaled-down test was conducted indoors. The arch abutment of the scaled-down model was a group-anchored reinforced concrete abutment. The left and right abutments were anchored with 26 and 28 M70 bolts respectively, based on the laboratory's ground anchor holes. The bolts were made of 40Cr steel, and their shear strength was used to resist the horizontal thrust of the main arch ring. Considering the complex stress at the arch foot, a 240 mm thick UHPC was poured at the arch abutment's starting surface for reinforcement.
[0026] For economic reasons and to maximize testing space, the rigid steel frame adopts a single-rib structure, with four main steel pipes, upper and lower horizontal bracing, and web members forming a frame-type steel truss arch. The steel truss arch uses a constant-width, variable-height cross-section. The transverse center-to-center distance between the two main steel pipes is 0.52 m, while the vertical center-to-center distances between the main steel pipes at the arch crown and arch foot are 0.68 m and 1.08 m, respectively. The main steel pipes of the rigid steel frame are available in two scaled-down sizes: Φ90×3.5 mm and Φ90×3 mm. Considering factors such as equivalent compressive stiffness, cross-sectional scaling ratio, material availability, and ease of fabrication, the main steel pipes uniformly use a Φ89×4 mm circular cross-section. The upper and lower horizontal bracing uses Φ32×4 mm circular steel pipes, and the web members use two sizes: Φ40×4 mm and Φ32×4 mm. The rigid steel frame is fabricated in six sections and assembled using a large-section lifting method, with a total weight of approximately 5.0 tons. The diameter of the concrete inside the pipes is 81 mm, with a total volume of approximately 1.5 m³. The main arch ring is encased in a constant-width, variable-height box girder. The box is 0.65 m wide, with heights of 0.8 m at the crown and 1.2 m at the arch foot. The web thickness gradually increases from 55 mm to 95 mm at the crown, the top slab thickness is 65 mm, and the bottom slab thickness gradually increases from 65 mm to 130 mm at the crown. A 50 cm long linear variable-section section is incorporated at the arch foot, linearly varying the web thickness from 95 mm to 145 mm, the bottom slab thickness from 130 mm to 170 mm, and the top slab thickness near the arch foot from 65 mm to 170 mm. The arch ribs are constructed using C60 self-compacting concrete, with a total volume of approximately 15 m³.
[0027] Furthermore, the array-type self-balancing pulley loading module also includes a real-time acquisition device, a counterweight statistics device, and a loading optimization device. The real-time acquisition device is used to collect the load at each loading point, the counterweight statistics device is used to calculate the theoretical counterweight value at each loading point in different construction stages, and the loading optimization device is used to calculate the counterweight reduction coefficient and actual loading value at each loading point in different construction stages.
[0028] In this embodiment of the invention, a loading point is arranged every 2 m along the longitudinal direction of the bridge, and the concentrated force at 29 loading points replaces the uniformly distributed load.
[0029] Furthermore, a single pulley loading device includes a fixed pulley block, a movable pulley block, a connecting rod, a fixed fixture, a lower fixture, a counterweight box, and a tension sensor. The fixed pulley block contains three fixed pulleys and is fixed to the ground by the lower fixture. The movable pulley block contains three movable pulleys and is connected to the main arch ring by the connecting rod and the fixed fixture. The winding cord passes through the movable pulley block and the fixed pulley block and then connects to the counterweight box at its end. The tension sensor is located at the connecting rod to collect the load values at the corresponding loading point in real time.
[0030] In this embodiment of the invention, the working principle of the pulley block loading scheme is as follows: Figure 2As 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, with a counterweight suspended at the end of the winding line; In the above loading scheme, the ratio of the actual load F borne by the loading point to the self-weight load G of the counterweight block is denoted as the load amplification factor, and is used as... The simplified calculation diagram is shown below. Figure 3 As shown. In Figure 3 In this study, taking pulley S2 as the object of study, it can be concluded from the principle of torque balance that... By analogy, we can obtain Therefore, the theoretical value of the load amplification factor of the single-point loading device under this design scheme can be obtained as follows: ; Design of a single pulley block loading device, such as Figure 4 and Figure 5 As shown in the diagram. In this device, the movable pulley block and the main arch ring are connected by the main arch ring fixing fixture and the connecting rod; the fixed pulley block and the ground are connected by the lower fixture and the lower fixture fixing seat; the counterweight box is used to place the counterweight blocks, which can be loaded in stages according to the test requirements; the tension sensor can display and collect the load value at the loading position of the main arch ring in real time. According to the test requirements, the loading devices were arranged sequentially along the longitudinal direction of the bridge to form an array-type pulley loading module, such as... Figure 6 As shown, even if the counterweight at a nearby loading point affects the vertical displacement of the current loading point, because the tension of the steel wire ropes on both sides of the same pulley is equal, the load amplification factor at the current loading point will approach 7 times again over time, exhibiting self-balancing characteristics. This system overcomes the drawbacks of the jack loading method, which has difficulty in maintaining long-term stable loading values; the lever method, which is easily affected by nearby loading points; and the direct counterweight method, which has excessively large counterweight blocks.
[0031] A graded loading test was conducted on a single pulley block loading system. The loading was divided into four levels, with each level containing a load of 0.2 t, 0.4 t, 0.6 t, and 0.8 t, respectively. After loading, the total mass of the counterweight box was 2.0 t. By reading real-time data from the tension sensor, the actual magnification of the pulley block loading system was obtained. The results are as follows: Figure 7As shown in the diagram, it can be seen that after each loading cycle, the load amplification factor of a single pulley system takes about 10 minutes to reach a stable state. This is because the wire rope needs to overcome the resistance at the pulleys to transfer the tension of the outermost wire rope layer by layer to the innermost wire rope. This process is called the hysteresis effect, and it is this effect that causes the load amplification factor to suddenly drop each time loading occurs, as shown at points A, B, C, and D in the diagram. Furthermore, after each loading cycle, the load amplification factor stabilizes at around 6.6 times, indicating that the mechanical efficiency of the single pulley system is approximately 94.29%, meeting the experimental requirements. Moreover, the influence of friction loss on the loading value can be eliminated through the specific readings of the tension sensor.
[0032] To verify the reliability and stability of the array-type loading module in practical applications, some loading points were selected during a certain stage of concrete pouring in the model test. The design loading values are shown in Table 1. The counterweight data of the relevant loading points were collected in real time using the Donghua DHDAS data acquisition system. The results are shown in Table 1. Figure 8 .
[0033] Table 1 shows the design load values for some loading points.
[0034] It can be seen that about 5 minutes after loading is completed at each loading point, the values of the tension sensors can reach the design load and remain basically stable. In addition, the load values of the 6th, 11th and 15th loading points are affected by the 6th, 11th and 15th loading points (excluding themselves). This is because the counterweight of the latter will generate vertical deflection at the loading position of the former. This deflection is transmitted to the movable pulley group, causing the movable pulley group and the fixed pulley group to move closer to each other, and the wire rope will slack to a certain extent, resulting in a decrease in the total load value. However, after about 5 minutes, each loading point will recover to the original load because the tension of the wire rope on both sides of the same pulley is equal. That is, the self-stabilizing characteristic of the system will make the mutual influence between the loading points disappear with time, which proves that the array pulley loading system has good stability and high reliability.
[0035] Furthermore, the multi-dimensional strain testing module includes a 16-point section strain testing device, an inter-segment interface strain testing device, and a temperature compensation device; among them, the 16-point section strain testing device has 17 strain testing sections evenly arranged along the longitudinal direction of the main arch ring, such as... Figure 9 As shown, 15 fiber optic strain sensors are deployed at each test section to collect concrete strain data from the bottom plate, web, and top plate concrete, as well as the inter-ring interfaces between the bottom plate and web, and between the web and top plate. The inter-segment interface strain testing device has six test sections set up at three inter-segment interfaces at the junctions of adjacent working faces, with one test section on each side of the interface. Figure 10 As shown; 15 fiber optic strain sensors are deployed at each test section, as follows. Figure 11As shown, strain data of the concrete in the top slab, bottom slab, and web were collected respectively. The temperature compensation device has three fiber optic temperature sensors evenly distributed in each strain test section and embedded in the concrete of the bottom slab, web, and top slab respectively to eliminate the influence of ambient temperature and heat of hydration of concrete on the strain data.
[0036] In an embodiment of the present invention, Figure 9 CS1~CS4 are embedded strain sensors, used to collect strain data of the bottom plate, top plate and web concrete respectively. CW1~CW8 are used to test the strain data of the concrete at the bottom plate-web ring interface and the web-top plate ring interface. In order to eliminate the influence of ambient temperature on strain data during construction, T1~T3 temperature sensors are embedded in the outer concrete, respectively arranged in the bottom plate, web and top plate concrete. exist Figure 10 In the diagram, the circled numbers in parentheses indicate the concrete pouring sequence. The three inter-section interfaces are located at the junctions of working faces 1 and 2, 2 and 3, and 3 and 4, respectively. These inter-section interfaces are designated as test sections 1 through 6, sequentially from the arch foot towards the mid-span. Figure 11 In the design, CS1~CS2, CS3~CS4 and CS5~CS10 are fiber optic strain sensors, which are used to collect stress data of the top plate, bottom plate and web plate concrete, respectively. In order to eliminate the influence of ambient temperature and concrete hydration heat on strain data, temperature sensors T1~T3 are sequentially arranged in the top plate, bottom plate and web plate concrete at the inter-section interface.
[0037] Furthermore, the multi-source displacement testing module includes a wire-type displacement testing device, a total station testing device, and a three-dimensional laser scanning testing device; such as Figure 12 As shown, the wire-type displacement testing device sets up 7 displacement testing sections at the 8th point of the main arch ring, with 4 wire-type displacement sensors deployed in each section; the total station testing device sets up 402 measuring points throughout the arch to supplement and verify the wire-type displacement data; the three-dimensional laser scanning testing device obtains the spatial alignment data of the entire bridge structure through multi-site scanning.
[0038] Furthermore, the portal frame limit protection module is arranged with a portal frame every 10m along the longitudinal direction of the main arch ring, for a total of 5 frames; the heights of the portal frames are 9m, 13m, 15m, 13m, and 9m respectively, and the width is 3.6m; the portal frame only restricts the lateral out-of-plane displacement of the main arch ring, and has no constraint on the longitudinal and vertical displacement of the structure.
[0039] Corresponding to the system, this invention also discloses a method for testing a large-scale scaled model of the main arch ring of an ultra-long span arch bridge, including the following steps: S1. Based on the similarity theory π theorem, complete the geometric, material, and construction scheme design of a large-scale scaled model using a large-span concrete arch bridge as the prototype; complete the construction of the arch seat, the assembly and closure of the stiffened steel frame, and the pouring of concrete inside the pipe. S2. Install the array-type self-balancing pulley block loading module, and determine the target counterweight value of each loading point in each construction stage through an automated counterweight statistics program and loading optimization algorithm; S3. Deploy multi-dimensional strain testing module and multi-source displacement testing module sensors and complete calibration and data acquisition debugging; S4. Install the portal-type limit protection module along the longitudinal direction of the main arch ring to complete the positioning and fixing; S5. The arching process of the main arch ring is divided into multiple construction stages. Following the principle of first loading the counterweight and then pouring the concrete, the graded loading, data synchronous collection and concrete pouring of each construction stage are completed in sequence until the concrete of the top plate of the main arch ring is closed. S6. Temperature correction is applied to the collected strain data, and multi-source displacement data is fused to analyze the stress evolution law, bearing mechanism and force transmission mechanism of the main arch ring during arch formation.
[0040] Furthermore, S2 specifically refers to: S21. Install a single set of pulley loading devices every 2m along the longitudinal direction of the main arch ring to form an array-type self-balancing loading module, and complete the connection and debugging of the tension sensor, real-time acquisition device, counterweight statistics device and loading optimization device. S22. Conduct a graded loading test on a single pulley group, with graded loading weights of 0.2t, 0.4t, 0.6t, and 0.8t, and calibrate the actual load amplification factor and mechanical efficiency of the device; S23. By importing the finite element model and construction stage division through the automated counterweight statistics program, the theoretical counterweight value of each loading point in each construction stage is automatically calculated. S24. Based on the counterweight reduction coefficient optimization algorithm, distinguish between overall stress and local stress components, calculate the counterweight reduction coefficient of each loading point in each construction stage, and determine the final actual loading value.
[0041] In this embodiment of the invention, the automatic calculation of the theoretical counterweight value at each loading point during each construction stage is specifically as follows: A counterweight load statistics program was developed using the ANSYS APDL programming language, which can automate the above tasks. Its basic workflow is as follows: Figure 15 As shown in the diagram, ArrayMass is a 20×29 two-dimensional array. The first dimension is used to store construction stage information, and the second dimension is used to store loading point numbers. ArrayPoint is a one-dimensional array with 28 elements, used to store... information; i Indicates the construction phase, take ;j This represents the element number in the finite element model. .
[0042] The main arch ring has a constant width and variable height cross-section, and the thickness of the outer concrete casing varies at different longitudinal locations. Simply distributing the weight of the main arch ring equally among all loading points is unreasonable. Instead, calculations and counterweights should be performed based on the actual dimensions and weight of the structure near each loading point. The specific calculation method is as follows: Let the ordinates of the centroids of the arch starting surfaces on the left and right sides be 0 and 60 respectively. Then, denote the ordinates of the 29 loading points from left to right as follows: Mark the ordinate of the midline between two adjacent loading points as And: ; No. i The counterweight value at loading point No. for: ; In the formula, Indicates the first j During each construction phase, the ordinate of the component's center of gravity is at... The total self-weight of all components already constructed within the scope.
[0043] Furthermore, the specific algorithm for optimizing the counterweight reduction factor in S24 is as follows: ; In the formula, For the first i In the first construction phase, the... j The weight reduction factor at each loading point The model arch is in the first i In the first construction phase, the... j The sum of the self-weights of the components near each loading point; The model bridge is represented in the first... i In the first construction phase, the... j The sum of the self-weights of the components near each loading point that participate in the overall structural stress; Indicates the first i In the first construction phase, the... j The sum of the self-weights of the components that participate in the local structural stress near the loading point after being scaled down from the actual bridge dimensions.
[0044] In this embodiment of the invention, to verify the correctness of the above optimization algorithm, finite element models of the actual bridge and the model arch were established using ANSYS APDL software. The stiffening steel frame and the concrete inside the pipe of both the actual bridge and the model test were simulated using Beam188 elements, while the outer concrete was simulated using Shell181 elements. The displacement and rotation of the arch feet on both sides of both bridges were constrained, and the construction process was simulated using birth and death elements. During the calculation, only the self-weight load was considered for the original bridge, while the model test, in addition to considering the self-weight load, also applied the vertical loads exerted on the structure by each set of pulley loading devices. The stiffening steel frame in both models was made of Q420 steel, the concrete inside the pipe was C80 concrete, and the outer concrete was C60 concrete. The effects of geometric nonlinearity and material nonlinearity were considered during the calculation. The stress values of the main steel tube, the concrete inside the tube, and the outer concrete of the stiffened steel frame of the actual bridge and the model test bridge during the construction process were extracted and compared. Some results are shown below. Figure 13 and Figure 14 As shown, the stress results of different components of the model bridge and the original bridge exhibit basically the same trend at each construction stage; the maximum difference in stress in the bottom slab concrete is 0.66 MPa. These results indicate that the main arch ring of the model bridge can effectively reflect the stress state during the actual bridge construction stage, verifying the correctness of the counterweight optimization algorithm for the array-type pulley loading system.
[0045] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0046] 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 or 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 large-scale scaled-down model test system for the main arch ring of an ultra-long span arch bridge, characterized in that, The system includes a scaled-down model test main structure, an array-type self-balancing pulley loading module, a multi-dimensional strain testing module, a multi-source displacement testing module, and a portal-type limiting protection module. The scaled-down model test main structure is based on the similarity theory π theorem and uses a large-span concrete arch bridge as a prototype. The array-type self-balancing pulley loading module includes multiple single-set pulley loading devices, which are sequentially arranged along the longitudinal direction of the main arch ring of the scaled-down model test main structure to simulate the uniformly distributed load throughout the construction process of the main arch ring. The multi-dimensional strain testing module is located at key sections and interfaces of the main arch ring to collect strain data of the entire cross-section, inter-ring interfaces, and inter-segment interfaces of the main arch ring throughout the construction process. The multi-source displacement testing module is located at key displacement sections of the main arch ring to collect deformation and spatial alignment data of the main arch ring throughout the construction process. The portal-type limiting protection module is spaced along the longitudinal direction of the main arch ring to restrict the lateral out-of-plane displacement of the main arch ring.
2. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, The scale of the main structure of the scaled-down model test is 1:
10.
3. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, The array-type self-balancing pulley loading module also includes a real-time acquisition device, a counterweight statistics device, and a loading optimization device. The real-time acquisition device is used to collect the load at each loading point, the counterweight statistics device is used to calculate the theoretical counterweight value at each loading point in different construction stages, and the loading optimization device is used to calculate the counterweight reduction coefficient and actual loading value at each loading point in different construction stages.
4. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, A single pulley loading device includes a fixed pulley block, a movable pulley block, a connecting rod, a fixed fixture, a lower fixture, a counterweight box, and a tension sensor. The fixed pulley block contains three fixed pulleys and is fixed to the ground by the lower fixture. The movable pulley block contains three movable pulleys and is connected to the main arch ring by the connecting rod and the fixed fixture. The winding cord passes through the movable pulley block and the fixed pulley block and then connects to the counterweight box at its end. The tension sensor is located at the connecting rod and collects the load values at the corresponding loading point in real time.
5. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, The multi-dimensional strain testing module includes a 16-point section strain testing device, an inter-segment interface strain testing device, and a temperature compensation device. The 16-point section strain testing device has 17 strain testing sections evenly arranged along the longitudinal direction of the main arch ring. Each testing section is equipped with 15 fiber optic strain sensors to collect strain data from the concrete of the bottom plate, web, and top plate, as well as the inter-ring interfaces between the bottom plate and web, and between the web and top plate. The inter-segment interface strain testing device has six testing sections, one on each side of the three inter-segment interfaces at the junction of adjacent working faces. Each testing section is equipped with 15 fiber optic strain sensors to collect strain data from the concrete of the top plate, bottom plate, and web. The temperature compensation device has three fiber optic temperature sensors evenly arranged in each strain testing section, embedded inside the concrete of the bottom plate, web, and top plate, to eliminate the influence of ambient temperature and concrete hydration heat on the strain data.
6. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, The multi-source displacement testing module includes a wire-type displacement testing device, a total station testing device, and a three-dimensional laser scanning testing device. The wire-type displacement testing device sets up 7 displacement testing sections at the 8th point of the main arch ring, with 4 wire-type displacement sensors deployed in each section. The total station testing device sets up 402 measuring points throughout the arch to supplement and verify the wire-type displacement data. The three-dimensional laser scanning testing device acquires the spatial alignment data of the entire bridge structure of the main arch through multi-site scanning.
7. The large-scale scaled model test system for the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, The portal frame limit protection module is arranged with a portal frame every 10m along the longitudinal direction of the main arch ring, for a total of 5 frames; the heights of the portal frames are 9m, 13m, 15m, 13m and 9m respectively, and the width is 3.6m; the portal frame only restricts the lateral out-of-plane displacement of the main arch ring, and has no constraint on the longitudinal and vertical displacement of the structure.
8. A method for large-scale scaled-down model testing of the main arch ring of an ultra-long span arch bridge, characterized in that, Includes the following steps: S1. Based on the similarity theory π theorem, complete the geometric, material, and construction scheme design of a large-scale scaled model using a large-span concrete arch bridge as the prototype; complete the construction of the arch seat, the assembly and closure of the stiffened steel frame, and the pouring of concrete inside the pipe. S2. Install the array-type self-balancing pulley block loading module, and determine the target counterweight value of each loading point in each construction stage through an automated counterweight statistics program and loading optimization algorithm; S3. Deploy multi-dimensional strain testing module and multi-source displacement testing module sensors and complete calibration and data acquisition debugging; S4. Install the portal-type limit protection module along the longitudinal direction of the main arch ring to complete the positioning and fixing; S5. The arching process of the main arch ring is divided into multiple construction stages. Following the principle of first loading the counterweight and then pouring the concrete, the graded loading, data synchronous collection and concrete pouring of each construction stage are completed in sequence until the concrete of the top plate of the main arch ring is closed. S6. Temperature correction is applied to the collected strain data, and multi-source displacement data is fused to analyze the stress evolution law, bearing mechanism and force transmission mechanism of the main arch ring during arch formation.
9. The method for large-scale scaled model testing of the main arch ring of a super-long span arch bridge according to claim 8, characterized in that, S2 specifically refers to: S21. Install a single set of pulley loading devices every 2m along the longitudinal direction of the main arch ring to form an array-type self-balancing loading module, and complete the connection and debugging of the tension sensor, real-time acquisition device, counterweight statistics device and loading optimization device. S22. Conduct a graded loading test on a single pulley group, with graded loading weights of 0.2t, 0.4t, 0.6t, and 0.8t, and calibrate the actual load amplification factor and mechanical efficiency of the device; S23. By importing the finite element model and construction stage division through the automated counterweight statistics program, the theoretical counterweight value of each loading point in each construction stage is automatically calculated. S24. Based on the counterweight reduction coefficient optimization algorithm, distinguish between overall stress and local stress components, calculate the counterweight reduction coefficient of each loading point in each construction stage, and determine the final actual loading value.
10. The method for large-scale scaled model testing of the main arch ring of a super-long span arch bridge according to claim 9, characterized in that, The specific algorithm for optimizing the counterweight reduction factor in S24 is as follows: ； In the formula, For the first i In the first construction phase, the... j The weight reduction factor at each loading point The model arch is in the first i In the first construction phase, the... j The sum of the self-weights of the components near each loading point; The model bridge is represented in the first... i In the first construction phase, the... j The sum of the self-weights of the components near each loading point that participate in the overall structural stress; Indicates the first i In the first construction phase, the... j The sum of the self-weights of the components that participate in the local structural stress near the loading point after being scaled down to the actual bridge dimensions.