A large-span arch bridge main arch ring large-scale model test method
By using a large-scale scaled-down model test method, the problems of construction process reproduction, loading stability and test accuracy in the test of ultra-long span stiffened concrete arch bridges were solved, and the test results were highly consistent with the actual bridge, providing reliable design and construction support.
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 model testing techniques for ultra-long span stiffened concrete arch bridges suffer from problems such as insufficient fidelity in the construction process, instability of the loading system, poor material compatibility, and low testing accuracy. These issues result in significant deviations between the test results and the actual bridge, making it impossible to provide reliable design and construction support.
A large-scale scaled-down model test method was adopted. Based on similarity theory, the scale ratio and physical parameter similarity ratio were determined. The stiff steel frame, concrete materials and loading devices were designed. Combined with data acquisition through multiple means, the construction process was strictly replicated and systematic data processing was carried out to ensure that the mechanical behavior of the model is consistent with that of the actual bridge.
It achieves strong experimental equivalence, high construction fidelity, stable and accurate loading, and reliable test data, providing reliable experimental data support and precise reference for actual bridge design and construction.
Smart Images
Figure CN122452172A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of bridge engineering testing technology, and more specifically to a method for testing a large-scale scaled model of the main arch ring of an ultra-long span arch bridge. Background Technology
[0002] As my country's transportation infrastructure network extends deeper into mountainous areas, ultra-long-span rigid-frame concrete arch bridges have become one of the core choices for large-span mountain bridges due to their outstanding advantages such as high stiffness, beautiful appearance, strong adaptability to mountainous terrain, and low maintenance costs. The construction of the main arch ring of this type of bridge adopts the core process of "rigid steel frame closure - in-tube concrete pouring - out-of-body concrete segmented pouring". The cross-sectional stiffness is asynchronously formed with the construction stage, the stress development process of each component is significantly different, the time-varying characteristics of the material are complex, and the control of the arch formation is extremely difficult.
[0003] Existing scaled-down model testing techniques for ultra-large span stiffness-reinforced arch main arch rings still have many shortcomings: some tests do not fully reproduce the key construction process of segmented casting of actual bridge rings, and ignore the impact of the gradual increase in cross-sectional stiffness on mechanical behavior; the loading system mostly adopts lever loading or direct counterweight methods, which have problems such as the loading values being easily affected by the interference of nearby loading points and poor long-term stability, making it difficult to achieve equivalent stress loading; the model materials are not adequately adapted to the scale ratio, the coarse aggregate particle size of the concrete inside the pipe is too large, which can easily lead to pipe blockage, and the compactness of the thin-walled section of the outer concrete is difficult to guarantee; the testing system mostly focuses on single-dimensional data acquisition, lacks temperature compensation design, and does not arrange measuring points for key parts such as the interfaces between rings and segments, making it difficult to accurately capture stress change characteristics; the selection of the scale ratio lacks systematic similarity theory support, which can easily lead to large deviations between the test results and the actual bridge due to scale effects.
[0004] The aforementioned problems make it difficult for experimental data to accurately reflect the mechanical behavior of the actual bridge arch formation process, thus failing to provide reliable support for bridge design optimization, construction stress control, and safety assessment. Therefore, there is an urgent need to propose a large-scale scaled model testing method that balances construction process fidelity, loading stability, material compatibility, and testing accuracy. This method would systematically address the pain points of existing technologies and provide theoretical and experimental support for the high-quality construction of ultra-long span stiffness-reinforced concrete arch bridges. Summary of the Invention
[0005] In view of this, the present invention provides a method for testing a large-scale scaled model of the main arch ring of an ultra-long span arch bridge, which solves the problems existing in the background technology.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for large-scale scaled-down model testing of the main arch ring of an ultra-long span arch bridge includes the following steps: S1. Clarify the core parameters and construction technology of the main arch ring of the bridge, determine the scaling ratio and the physical parameter similarity ratio between the model and the actual bridge based on similarity theory, and take stress equivalence as the core design principle. S2. Based on the scaling ratio and physical parameter similarity ratio, design the structural form and dimensions of the rigid steel frame, outer concrete and arch abutment, select steel and concrete materials that match the performance of the actual bridge, and adapt to the construction requirements of the scaled model. S3. Arrange array-type self-balancing loading devices along the longitudinal direction of the main arch ring of the model. Amplify the load to achieve equivalent loading through load amplification design. Optimize the load application at each construction stage by combining the stress characteristics of the components. S4. Set up strain test sections at key sections and interface locations of the main arch ring, and arrange strain sensors and temperature compensation devices; set up displacement test sections at preset locations, and use multiple methods to collect displacement and linear data in a coordinated manner. S5. Limiting devices are arranged along the longitudinal direction of the main arch ring to restrict only the lateral displacement, without constraining the longitudinal and vertical deformation, thus ensuring the structural stability during the test. S6. Referring to the actual bridge construction process, the construction stages are divided according to the sequence of stiff steel frame closure, in-pipe concrete pouring, outer concrete ring and segment pouring, and load application at each stage. The operation of each stage is executed based on the preset process and data is collected synchronously. S7. Systematically process the experimental data and verify the reliability of the experimental method by comparing it with the simulation results.
[0007] Optionally, in S1, the physical parameter similarity ratio includes the similarity relationships corresponding to geometric dimensions, stress, strain, elastic modulus, area, volume, moment of inertia of cross section, force, and moment. All similarity relationships are based on similarity theory. The theorem derivation is confirmed to ensure consistency between the model and the mechanical behavior of the actual bridge.
[0008] Optionally, in S2, the specific requirements for the concrete material to be adapted to the scaled-down model construction are as follows: the concrete inside the pipe should be of the self-compacting micro-expansion type, and the outer concrete should be made of fine aggregate to ensure that the fluidity and density of the concrete meet the pouring or casting construction requirements of the scaled-down model.
[0009] Optionally, in S3, the array-type self-balancing loading device consists of a fixed pulley block, a movable pulley block, a counterweight assembly, and a force sensor. The load is amplified through a winding design, and the loading device cancels out the interference of the displacement of the adjacent loading point on the load of the current loading point through its self-balancing characteristics.
[0010] Optionally, in S3, when optimizing the loads applied at each construction stage, the principle of equivalent counterweight for the overall load-bearing components based on their actual dimensions and equivalent counterweight for the local load-bearing components based on the scaled-down version of the actual bridge is followed, and the load optimization coefficient for each loading point is determined separately according to the construction stage.
[0011] Optionally, in S4, the key sections include: the longitudinally bisected section of the main arch ring and the section at the junction of adjacent working surfaces of each ring concrete; the multi-method collaborative acquisition specifically involves: the use of wire-type displacement sensors, total stations, and 3D laser scanners to achieve complementary verification of displacement and alignment data.
[0012] Optionally, in S4, the temperature compensation device is a temperature sensor, which is arranged at the corresponding position of the strain test section to eliminate the interference of ambient temperature and concrete hydration heat on the strain test data.
[0013] Optionally, in S5, the limiting device is a portal frame structure, arranged at intervals along the longitudinal direction of the main arch ring. The height of the portal frame is designed to be adapted to the elevation of the model arch axis, ensuring that only the lateral displacement of the structure is limited without generating additional constraints.
[0014] Optionally, in S6, the concrete outer casing is poured in rings and segments as follows: the bottom plate, web plate, and top plate are divided into rings, and multiple working faces are divided longitudinally. Each working face is poured in multiple segments symmetrically, and the pouring sequence is completely consistent with the actual bridge construction process.
[0015] Optionally, in S7, the test data is systematically processed, including data filtering, temperature correction, and outlier removal. By comparing with the finite element simulation results, the relative error meeting the preset requirements is used as the verification standard for the reliability of the test method.
[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for large-scale scaled model testing of the main arch ring of an ultra-long span arch bridge, which has the following beneficial effects: (1) Strong experimental equivalence: based on similarity theory The theorem determines the scaling ratio and physical parameter similarity ratio. With stress equivalence as the core design principle, and combined with the optimization logic of "differentiated counterweight of overall / local stressed components", the model is highly consistent with the mechanical behavior of the actual bridge. The test results can directly provide support for the design and construction of the actual bridge.
[0017] (2) High degree of construction reproduction: It strictly replicates the entire process of the actual bridge, from "combination of rigid steel frame - pouring of concrete inside the pipe - pouring of concrete in sections and rings", accurately simulates the asynchronous forming process of cross-sectional stiffness, and truly reflects the stress and deformation characteristics of each construction stage, thus solving the problem of traditional tests neglecting key construction links.
[0018] (3) Stable and accurate loading: The array-type self-balancing loading device is adopted. Through load amplification design and self-balancing characteristics, the interference of nearby loading points is offset, and the loading stability and accuracy are significantly improved. Combined with dynamic optimization of the load during the construction stage, the numerical drift problem of traditional loading methods is avoided.
[0019] (4) Reliable test data: Measurement points are arranged for key sections and inter-ring / inter-segment interfaces. Strain sensors and temperature compensation devices are integrated, and multiple methods are used to collect displacement and linear data in a coordinated manner to effectively eliminate environmental interference and achieve accurate capture and complementary verification of stress and displacement data.
[0020] (5) Excellent applicability and safety: It is suitable for the test requirements of the main arch ring of the ultra-large span stiff skeleton arch. The portal frame limiting device ensures the lateral stability of the test process. The technical solution takes into account both construction feasibility and operation standardization, and provides a standardized and reproducible method for scaled-down model tests of similar bridges. Attached Figure Description
[0021] 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.
[0022] Figure 1 The flowchart shows the test method for a large-scale scaled model of the main arch ring of an ultra-large span arch bridge provided by this invention. Detailed Implementation
[0023] 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.
[0024] This invention discloses a method for testing a large-scale scaled model of the main arch ring of an ultra-long span arch bridge, such as... Figure 1 As shown, it includes the following steps: S1. Clarify the core parameters and construction technology of the main arch ring of the bridge, determine the scaling ratio and the physical parameter similarity ratio between the model and the actual bridge based on similarity theory, and take stress equivalence as the core design principle. S2. Based on the scaling ratio and physical parameter similarity ratio, design the structural form and dimensions of the rigid steel frame, outer concrete and arch abutment, select steel and concrete materials that match the performance of the actual bridge, and adapt to the construction requirements of the scaled model. S3. Arrange array-type self-balancing loading devices along the longitudinal direction of the main arch ring of the model. Amplify the load to achieve equivalent loading through load amplification design. Optimize the load application at each construction stage by combining the stress characteristics of the components. S4. Set up strain test sections at key sections and interface locations of the main arch ring, and arrange strain sensors and temperature compensation devices; set up displacement test sections at preset locations, and use multiple methods to collect displacement and linear data in a coordinated manner. S5. Limiting devices are arranged along the longitudinal direction of the main arch ring to restrict only the lateral displacement, without constraining the longitudinal and vertical deformation, thus ensuring the structural stability during the test. S6. Referring to the actual bridge construction process, the construction stages are divided according to the sequence of stiff steel frame closure, in-pipe concrete pouring, outer concrete ring and segment pouring, and load application at each stage. The operation of each stage is executed based on the preset process and data is collected synchronously. S7. Systematically process the experimental data and verify the reliability of the experimental method by comparing it with the simulation results.
[0025] Existing scale-down tests often suffer from ambiguous similarity relationships, focusing only on geometric scaling and neglecting the equivalent matching of key mechanical parameters such as stress and moment. This leads to significant deviations between the test results and the actual bridge, failing to accurately reflect the actual bridge's mechanical behavior. To address this issue, in S1 of this embodiment, the physical parameter similarity ratio includes similarity relationships corresponding to geometric dimensions, stress, strain, elastic modulus, area, volume, moment of inertia of cross section, force, and moment. All similarity relationships are based on similarity theory. The theorem derivation is confirmed to ensure consistency between the model and the mechanical behavior of the actual bridge. This embodiment utilizes similarity theory. The theorem system derives the similarity relationship of physical parameters in all dimensions, and constructs a multi-dimensional equivalent system of "geometry-mechanics-energy". This avoids the scale effect deviation caused by the scaling of a single parameter, and can make the model and the actual bridge highly consistent in core mechanical properties such as stress transmission and deformation response. The mapping of experimental data is significantly improved, providing accurate reference for the design and construction of actual bridges.
[0026] Specifically, when determining the scaling ratio, S1 comprehensively considers the test space, structural manufacturability, material scale effect, and construction feasibility, and prioritizes a 1:10 scaling ratio. When deriving the similarity ratio of physical parameters, it focuses on ensuring that the similarity ratio of stress, strain, and elastic modulus is 1:1, and the similarity ratio of unit weight is 10:1, so as to achieve the core objective of "stress equivalence" and avoid load simulation distortion caused by differences in unit weight.
[0027] In the scaled-down model, the inner diameter of the main steel pipe and the cross-sectional dimensions of the thin-walled outer concrete are significantly reduced. Traditional concrete with excessively large coarse aggregate particle sizes can easily lead to pipe blockage during grouting and insufficient compaction of the outer concrete. Furthermore, the shrinkage of ordinary concrete can easily cause interface cracking, affecting the overall integrity of the model. To address this issue, in S2 of this embodiment, the concrete material is adapted to the construction requirements of the scaled-down model as follows: the inner concrete uses a self-compacting, micro-expansion type, and the outer concrete uses fine-grained aggregate to ensure that the fluidity and density of the concrete meet the grouting or pouring requirements of the scaled-down model.
[0028] In the above scheme, considering the limited construction space of the scaled-down model, this embodiment optimizes the properties of concrete materials. The concrete inside the self-compacting micro-expansion pipe can achieve self-leveling pouring without vibration, and the fine-grained aggregate-encased concrete is suitable for thin-walled section pouring. At the same time, the micro-expansion characteristics offset shrinkage deformation. This method can avoid the risk of concrete blockage inside the pipe, ensure the compactness of the encased concrete, reduce the risk of interface cracking, significantly improve the integrity of the model structure and the matching degree of material properties, and enhance the consistency with the workability and mechanical effects of the actual bridge concrete.
[0029] Traditional lever loading or direct counterweight methods are susceptible to displacement of nearby loading points, leading to load value drift, poor long-term stability, and difficulty in achieving large-scale equivalent loading, thus failing to meet stress equivalence requirements. To address this issue, in S3 of this embodiment, the array-type self-balancing loading device consists of a fixed pulley system, a movable pulley system, a counterweight assembly, and a force sensor. Load amplification is achieved through a winding design, and the loading device uses its self-balancing characteristics to counteract the interference of nearby loading point displacements on the current loading point load.
[0030] Specifically, the pulley block of the array-type self-balancing loading device adopts a "3 fixed and 3 moving" winding method, with a load amplification factor designed to be 7 times. Before actual use, a single set of devices needs to be calibrated by graded loading (loading levels are 0.2t, 0.4t, 0.6t, and 0.8t) to ensure that the mechanical efficiency is stable at over 94%. The counterweight component uses standardized cast iron counterweight blocks, with a single block weighing 50kg, which facilitates graded loading and precise adjustment. The force sensor is a high-precision tensile and compressive force sensor with a range of 0-50kN and an accuracy class of 0.1, which collects data in real time and transmits it to the data acquisition system.
[0031] In the above scheme, this embodiment adopts a combination design of fixed pulley blocks and movable pulley blocks. The load is amplified by reasonable winding. The force sensor monitors the load value in real time. The self-balancing characteristic can automatically cancel the load interference caused by the displacement of adjacent loading points, ensuring that the load at each loading point is independent and stable. The loading device has high mechanical efficiency, the load value is stable in the long term, and the loading accuracy is significantly improved. It can accurately simulate the load action at each stage of the actual bridge construction process, providing a reliable guarantee for stress equivalent test.
[0032] In the scaled-down model, some components have undergone dimensional adjustments due to manufacturing processes and structural safety requirements (such as thickening the main steel pipe wall and strengthening local concrete sections). If a uniform weight ratio is used, it will lead to local stress distortion and fail to reflect the actual stress state of the actual bridge. To address this issue, in S3 of this embodiment, when optimizing the load application at each construction stage, the principle of equivalent weight distribution for overall load-bearing components based on actual dimensions and equivalent weight distribution for local load-bearing components based on the scaled-down version of the actual bridge is followed. The load optimization coefficient for each loading point is determined separately according to the construction stage.
[0033] In the above scheme, this embodiment distinguishes between overall stressed components and locally stressed components based on the differences in the stress characteristics of the components, and adopts different counterweight calculation logics for each. The loading values at each construction stage are dynamically adjusted through the load optimization coefficient to correct the stress deviation caused by the size adjustment. Based on this method, the load of each construction stage can be accurately matched, the stress state of each part of the model is significantly improved to match the actual bridge, the test error caused by the size adjustment of local components is avoided, and the authenticity and reliability of the test data are ensured.
[0034] Existing experiments often only arrange measuring points on longitudinally bisected sections, neglecting critical areas of stress abrupt changes such as interfaces between rings and segments. Furthermore, single testing methods have limitations (e.g., wire-type sensors are easily obstructed, and total stations have insufficient measuring point density), leading to incomplete data acquisition and insufficient accuracy. To address this issue, in S4 of this embodiment, key sections include: the longitudinally bisected section of the main arch ring and the section at the intersection of adjacent working surfaces of each ring's concrete. The multi-method collaborative acquisition specifically involves the combined use of wire-type displacement sensors, a total station, and a 3D laser scanner to achieve complementary verification of displacement and alignment data. The 3D laser scanner is a phase-type scanner with a scanning accuracy of ±0.1mm and a scanning interval of 5mm. Target calibration is performed before each scan to ensure accurate alignment data.
[0035] In the above scheme, this embodiment specifically selects longitudinally bisected sections and inter-ring / inter-segment interfaces as test sections, fully covering key areas of stress change; it integrates the real-time capability of wire-type sensors, the accuracy of total stations, and the global reach of 3D laser scanners to construct a multi-dimensional testing system, achieving cross-validation of displacement and alignment data. Based on this method, the stress abrupt change characteristics of inter-ring and inter-segment interfaces can be accurately captured, comprehensively acquiring the displacement and alignment data of the main arch ring, significantly improving data redundancy and reliability, and providing rich data support for analyzing structural mechanical behavior.
[0036] During the experiment, changes in ambient temperature and the release of heat from concrete hydration can cause false strain readings in the strain sensors, masking the true stress and strain of the structure and affecting the accuracy of the test data. To address this issue, in S4 of this embodiment, a temperature compensation device is a temperature sensor, positioned at the corresponding location on the strain test section, to eliminate the interference of ambient temperature and heat from concrete hydration on the strain test data. Specifically, a PT1000 platinum resistance temperature sensor is selected, with a measurement range of -50℃ to 200℃ and an accuracy of ±0.1℃, and is arranged in a one-to-one correspondence with the strain sensors. The strain sensors are fiber optic strain sensors, installed in an embedded manner, ensuring a tight fit between the sensor and the concrete during installation to prevent slippage.
[0037] In the above scheme, temperature sensors are synchronously arranged at the strain test section to collect changes in ambient temperature and internal concrete temperature in real time. Through a temperature-strain coupling correction algorithm, spurious strain caused by temperature factors is eliminated. This method can significantly reduce the impact of temperature interference on test data, greatly improve the accuracy of strain testing, and ensure that the obtained strain data truly reflects the stress state of the structure, providing an accurate data foundation for mechanical behavior analysis.
[0038] Large-scale scaled models have a high slenderness ratio, making them prone to out-of-plane instability during construction. Traditional limiting devices often suffer from excessive constraint, restricting the normal longitudinal or vertical deformation of the main arch ring and causing distortion of the stress state. To address this issue, in S5 of this embodiment, the limiting device is a portal frame structure, arranged at intervals along the longitudinal direction of the main arch ring. The height of the portal frame is designed to adapt to the elevation of the model's arch axis, ensuring that only the lateral displacement of the structure is restricted without generating additional constraints.
[0039] In the above scheme, this embodiment adopts a portal frame structure. Through height adaptation design, it fits the model arch axis elevation. Limiting constraints are only set in the horizontal direction, while sufficient deformation space is reserved in the longitudinal and vertical directions to avoid generating additional constraint stress. This method can effectively prevent out-of-plane instability of the structure during the test, ensure test safety, not interfere with the normal stress deformation of the main arch ring, ensure the consistency of the stress state of the model with the actual bridge, and avoid test errors caused by improper constraints.
[0040] The segmented and ring-shaped casting of the outer concrete of a super-long span stiffness arch bridge is a core characteristic of actual bridge construction. The cross-sectional stiffness develops asynchronously during the casting process. Simplifying the casting process (such as casting in one go) cannot simulate the gradual change in structural stiffness and the stress accumulation effect at each stage. To address this issue, in S6 of this embodiment, the segmented and ring-shaped casting of the outer concrete is specifically as follows: the bridge is divided into rings according to the bottom slab, web, and top slab, and multiple working faces are longitudinally divided. Each working face is divided into multiple symmetrical segments for casting, and the casting sequence is completely consistent with the actual bridge construction process.
[0041] In the above scheme, this embodiment strictly replicates the actual bridge casting logic, dividing the bridge into rings according to the bottom plate, web plate, and top plate, and casting multiple working surfaces and multiple sections symmetrically in the longitudinal direction. It synchronously simulates the application of loads at each stage and truly restores the asynchronous forming process of cross-sectional stiffness. This method can accurately simulate the stress evolution and deformation accumulation during the actual bridge construction process, and completely reproduce the structural mechanical behavior at each construction stage, providing reliable experimental basis for analyzing risk points (such as stress concentration and excessive deformation) during the construction process.
[0042] The raw experimental data contains outliers caused by environmental interference and equipment errors, and these outliers have not been systematically corrected. Directly using them for analysis can lead to biased conclusions. Furthermore, the lack of clear reliability verification standards makes it impossible to determine the effectiveness of the experimental method. To address this issue, in S7 of this embodiment, the experimental data undergoes systematic processing, including data filtering, temperature correction, and outlier removal. By comparing the data with finite element simulation results, the relative error meeting preset requirements is used as the verification standard for the reliability of the experimental method.
[0043] In the above scheme, this embodiment establishes a system processing flow of "data screening - temperature correction - outlier removal" to purify the test data; constructs a finite element simulation model, and clarifies the quantitative standard for the reliability of the test method through relative error analysis between the test data and simulation results; this method can obtain high-quality and highly reliable test data, verify the effectiveness of the test method through quantitative comparison, ensure the scientificity and rigor of the test conclusions, and provide reliable technical support for the design and construction of actual bridges.
[0044] 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.
[0045] The above description of the disclosed embodiments enables those skilled in the art to make or 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 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 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. Clarify the core parameters and construction technology of the main arch ring of the bridge, determine the scaling ratio and the physical parameter similarity ratio between the model and the actual bridge based on similarity theory, and take stress equivalence as the core design principle. S2. Based on the scaling ratio and physical parameter similarity ratio, design the structural form and dimensions of the rigid steel frame, outer concrete and arch abutment, select steel and concrete materials that match the performance of the actual bridge, and adapt to the construction requirements of the scaled model. S3. Arrange array-type self-balancing loading devices along the longitudinal direction of the main arch ring of the model. Amplify the load to achieve equivalent loading through load amplification design. Optimize the load application at each construction stage by combining the stress characteristics of the components. S4. Set up strain test sections at key sections and interface locations of the main arch ring, and arrange strain sensors and temperature compensation devices; set up displacement test sections at preset locations, and use multiple methods to collect displacement and linear data in a coordinated manner. S5. Limiting devices are arranged along the longitudinal direction of the main arch ring to restrict only the lateral displacement, without constraining the longitudinal and vertical deformation, thus ensuring the structural stability during the test. S6. Referring to the actual bridge construction process, the construction stages are divided according to the sequence of stiff steel frame closure, in-pipe concrete pouring, outer concrete ring and segment pouring, and load application at each stage. The operation of each stage is executed based on the preset process and data is collected synchronously. S7. Systematically process the experimental data and verify the reliability of the experimental method by comparing it with the simulation results.
2. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S1, the physical parameter similarity ratios include the similarity relationships corresponding to geometric dimensions, stress, strain, elastic modulus, area, volume, moment of inertia of cross sections, force, and moment. All similarity relationships are based on similarity theory. The theorem derivation is confirmed to ensure consistency between the model and the mechanical behavior of the actual bridge.
3. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S2, the specific requirements for the construction of the scaled-down model using concrete materials are as follows: the concrete inside the pipe should be of the self-compacting micro-expansion type, and the outer concrete should be made of fine aggregate to ensure that the fluidity and density of the concrete meet the pouring or casting requirements of the scaled-down model.
4. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S3, the array-type self-balancing loading device consists of a fixed pulley block, a movable pulley block, a counterweight assembly, and a force sensor. The load is amplified through a winding design, and the loading device cancels out the interference of the displacement of the adjacent loading point on the load of the current loading point through its self-balancing characteristics.
5. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S3, when optimizing the load application at each construction stage, the principle of equivalent counterweight for the overall load-bearing components according to the actual size and equivalent counterweight for the local load-bearing components according to the scaled-down version of the actual bridge is followed, and the load optimization coefficient for each loading point is determined separately according to the construction stage.
6. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S4, key sections include: the longitudinally bisected section of the main arch ring and the section at the junction of adjacent working surfaces of each ring concrete. The multi-method collaborative acquisition specifically involves the use of wire-type displacement sensors, total stations, and 3D laser scanners to achieve complementary verification of displacement and alignment data.
7. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S4, the temperature compensation device is a temperature sensor, which is placed at the corresponding position of the strain test section to eliminate the interference of ambient temperature and concrete hydration heat on the strain test data.
8. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S5, the limiting device is a portal frame structure, which is arranged at intervals along the longitudinal direction of the main arch ring. The height of the portal frame is designed to be adapted to the elevation of the model arch axis, so as to ensure that only the lateral displacement of the structure is limited without generating additional constraints.
9. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S6, the concrete outer casing is poured in rings and segments as follows: the bottom plate, web plate and top plate are divided into rings, and multiple working faces are divided longitudinally. Each working face is poured in multiple segments symmetrically. The pouring sequence is completely consistent with the actual bridge construction process.
10. The method for large-scale scaled-down model testing of the main arch ring of a super-long span arch bridge according to claim 1, characterized in that, In S7, the test data is systematically processed, including data filtering, temperature correction, and outlier removal. By comparing with the finite element simulation results, the relative error meeting the preset requirements is used as the verification standard for the reliability of the test method.