Full-bridge elastic scale model component of deepwater cable-stayed bridge for hydrodynamic test and application thereof

Abstract

The application discloses a deep-water cable-stayed bridge full-bridge elastic scale model component for hydrodynamic test and application thereof. The deep-water cable-stayed bridge full-bridge elastic scale model component has a manufacturing method including the following steps: determining the similarity ratios of various physical quantities of the model components and the original bridge components according to geometric similarity criteria and dynamic similarity criteria, including the shape geometric size similarity ratio, the mass similarity ratio, the elastic modulus similarity ratio, the cross-section inertia moment similarity ratio, the bending stiffness similarity ratio, the cross-section area similarity ratio and the axial stiffness similarity ratio; selecting materials and processing the model components to at least meet the shape geometric size similarity ratio, the bending stiffness similarity ratio and / or the axial stiffness similarity ratio; when the mass similarity ratio of the model component mass and the corresponding original bridge component mass is not met, the model component is counterweighted according to the difference between the model component mass and the original bridge component mass after scaling; and the model components are spliced to obtain the deep-water cable-stayed bridge full-bridge elastic scale model component.

Description

Technical Field

[0001] This invention relates to the technical field of bridge engineering, and more specifically, to an elastic scale model component of a deep-water cable-stayed bridge for hydrodynamic testing and its application. Background Technology

[0002] Unlike inland bridges, cross-sea bridges typically have their foundations buried in the complex environment of the seabed and seawater, making waves and currents critical loads in structural design. Deep-water cable-stayed bridges, a typical structural form among cross-sea bridges, are characterized by large spans, towering towers, and pile foundations extending tens or even hundreds of meters underwater. Their main tower foundations bear significant hydrodynamic loads under the influence of waves and currents. Furthermore, the superstructure is coupled to the towers via stay cables, further complicating the structure's dynamic response mechanism. Studying the structural response characteristics under these critical loads is an important aspect of theoretical research on cross-sea bridges and can provide a reference for practical engineering projects.

[0003] In terms of research methods, although modern computer and engineering numerical simulation technologies have made significant progress, greatly expanding the scope of computational solutions, many problems still remain uncomputable. For example, the fluid-structure interaction dynamic response of a deep-water cable-stayed bridge system under the combined action of waves and currents involves complex interactions between multi-scale components and the flow field, making comprehensive and accurate numerical simulation difficult. Model testing remains a crucial means of addressing these issues. Furthermore, numerical methods or calculations proposed with simplifications and assumptions for complex problems often require verification through model testing. Conducting experiments using scaled-down models in flumes, flow channels, or wave pools not only allows for direct observation of complex fluid-structure interaction processes but also provides experimental evidence for scour protection, structural design, and durability assessment.

[0004] Currently, numerous research results have been achieved in the similarity theory of fluid-structure interaction model tests in aquatic environments. When the deformation of the structure itself is not the focus, but rather the flow characteristics of the flow field and the hydrodynamic pressure of the fluid on the structure surface, model tests mainly consider the flow similarity of the fluid. However, when studying hydraulic structures such as offshore bridges, dams, offshore wind turbines, and offshore platforms, and investigating the elastic and dynamic response characteristics of the structure under fluid action, model tests must simultaneously consider the dynamic similarity of the structure, the flow similarity of the fluid, and the hydrodynamic pressure effect similarity under fluid-structure interaction. To date, however, there is no universally applicable similarity theory or model design method, and there are still shortcomings in simultaneously satisfying geometric, dynamic, and hydrodynamic similarities.

[0005] Especially for deep-water cable-stayed bridges, their structural composition is complex, including bridge towers, piers, and pile groups that mainly resist bending, as well as cable stays that mainly bear axial forces, and near-rigid abutments. The stiffness characteristics of various components differ significantly, which places higher demands on the material selection and cross-section design of scaled-down models. At the same time, the underwater geometry of large-scale pile foundations in deep water has a significant impact on wave diffraction and current separation. The model must ensure both structural elastic similarity and geometric similarity, making the traditional single-component scaling-down method difficult to apply to hydroelastic model tests of the entire bridge system. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a scaled-down model component of a deep-water cable-stayed bridge for hydrodynamic testing that can balance structural elasticity similarity and geometric similarity, and its application. The technical solution is as follows:

[0007] The fabrication method for an elastic scaled-down model of a deep-water cable-stayed bridge used for hydrodynamic testing includes the following steps:

[0008] Step 100: Determine the similarity ratios of various physical quantities between the model component and the original bridge component according to the geometric similarity criteria and the dynamic similarity criteria. The similarity ratios of various physical quantities include the similarity ratio of external geometric dimensions, as well as the similarity ratios of mass, elastic modulus, moment of inertia, bending stiffness, cross-sectional area, and axial stiffness expressed by the similarity ratio of external geometric dimensions. Among them, the bending stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the moment of inertia similarity ratio, and the axial stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the cross-sectional area similarity ratio.

[0009] Step 200: Select materials and process them into model components that at least meet the similarity ratio of external geometric dimensions, bending stiffness, and / or axial stiffness; wherein, when the mass of the model component does not meet the mass similarity ratio with the corresponding original bridge component, the model component is counterweighted according to the difference between the mass of the model component and the scaled-down mass of the original bridge component.

[0010] Step 300: Assemble the model components to obtain the elastic scale model components of the entire deep-water cable-stayed bridge.

[0011] The advantages of the elastic scaled-down model component of the deep-water cable-stayed bridge for hydrodynamic testing of the present invention are as follows: (1) By systematically determining the similarity ratio of various physical quantities such as the external geometric dimensions in step 100 according to the geometric similarity criteria and the dynamic similarity criteria, a complete theoretical framework is established that uses the geometric similarity ratio as the basic quantity to uniformly express the similarity ratio of various mechanical parameters. This allows the scaled-down design of various components of the deep-water cable-stayed bridge to be carried out under the same similarity system, avoiding the problem of distortion of the mechanical behavior of the entire bridge system caused by designing each component according to different criteria. (2) Step 200 constrains the processing of the model component to ensure that it at least simultaneously satisfies the similarity ratio of external geometric dimensions, the similarity ratio of bending stiffness, and the similarity ratio of axial stiffness. This allows the scaled-down model to not only restore the elastic deformation and dynamic response characteristics of the original bridge component under the action of waves and ocean currents, but also maintain the same external geometric contour as the original bridge. This ensures that the diffraction, separation, and wake characteristics generated when the fluid passes around the model component are similar to the prototype, thus achieving the synergistic satisfaction of structural elastic similarity and external geometric similarity. (3) Step 200 further introduces a counterweight mechanism. When the mass of the model component cannot meet the mass similarity ratio due to the difference in material density between the model component and the original bridge material, the counterweight is adjusted according to the difference between the mass of the model component and the mass of the scaled-down original bridge component. This ensures that the mass distribution of the whole bridge model is similar to that of the original bridge, thereby ensuring that the dynamic characteristics (such as natural frequency and mode shape) of the model structure under the action of gravity and fluid inertial force are consistent with the elastic-gravity dynamic similarity relationship of the original bridge. This makes up for the insufficiency of relying solely on material and cross-section design to accurately control stiffness and mass at the same time. (4) Step 300 splices the model components to form the whole bridge system, so that the connection and constraint relationship between the components can be completely restored. The whole bridge model can reflect the coupled dynamic effect between the substructures of the deep-water cable-stayed bridge.

[0012] In summary, this invention, through the coordinated efforts of three steps, forms a systematic approach from the establishment of similarity theory and the design and fabrication of single components to the integration of the entire bridge system. It solves the technical problems in existing hydroelastic model tests for the lack of a systematic design method for the entire deep-water cable-stayed bridge system and the difficulty in balancing structural elastic similarity and geometric similarity. It provides a reliable experimental model for the study of the fluid-structure interaction dynamic response of deep-water cable-stayed bridges under the combined action of waves and ocean currents.

[0013] As a further improvement to the aforementioned elastic scale model component of the deep-water cable-stayed bridge: the equivalent average volume density of the model component and the original bridge component are taken to be equal, and the similarity ratio of the external geometric dimensions is obtained. The mass similarity ratio is represented as This ensures that the ratio of gravity and buoyancy experienced by the model in water is consistent with that of the original bridge, and at the same time provides basic constraints on mass distribution for the accurate simulation of inertial forces in hydrodynamic experiments.

[0014] As a further improvement to the aforementioned elastic scale model component of the deep-water cable-stayed bridge: based on the dynamic equilibrium equation, geometric equation, and physical equation, an elastic-gravity similarity relationship is established. The equivalent average volume density of the model component is taken to be equal to that of the original bridge component, resulting in a similarity ratio based on the external geometric dimensions. The similarity ratio of the elastic modulus is represented as This ensures that the ratio of gravity effect to elastic restoring force in the model remains consistent with that of the original bridge, guaranteeing that the deformation and dynamic response of the model under the combined action of its own weight and wave force meet the elastic-gravity similarity requirements.

[0015] As a further improvement to the above-mentioned elastic scale model of the entire deep-water cable-stayed bridge: the similarity ratio of the moment of inertia of the cross sections is... ,according to , The similarity ratio of bending stiffness is obtained as follows: This ensures that the bending deflection and curvature distribution of each bending component under the action of waves and ocean currents remain similar to those of the original bridge.

[0016] As a further improvement to the aforementioned elastic scale model of the entire deep-water cable-stayed bridge: the cross-sectional area similarity ratio is... ,according to , The axial stiffness similarity ratio is obtained as follows: This ensures that the axial expansion and contraction deformation of the model remains similar to that of the original bridge.

[0017] As a further improvement to the aforementioned elastic scaled-down model components of the deep-water cable-stayed bridge: In step 200, the model components include the main tower pier foundation, auxiliary pier pile foundation, main beam, and stay cables; among them, the main tower pier foundation, auxiliary pier pile foundation, and main beam adopt an inner skeleton-outer mold combination structure. The materials are selected and processed according to the inner skeleton satisfying the bending stiffness similarity ratio and / or axial stiffness similarity ratio, and the outer mold satisfying the geometrical similarity ratio. Thus, the elastic similarity requirements and the shape similarity requirements are decoupled to two independent structural levels and implemented separately. This overcomes the contradiction that a single material cannot simultaneously satisfy both stiffness and shape constraints, and ensures the correct reproduction of the flow field diffraction and separation characteristics of the model's outer surface geometry.

[0018] As a further improvement to the aforementioned elastic scale model components of the deep-water cable-stayed bridge: the main tower pier foundation includes bridge towers, main abutments, and main pile groups distributed from top to bottom; the auxiliary pier pile foundation includes pier columns, auxiliary abutments, and auxiliary pile groups distributed from top to bottom; the inner skeleton of the bridge towers and pier columns is made of steel, and the outer mold is made of polylactic acid fiber composite material and spliced ​​from U-shaped parts; the inner skeleton of the main abutments and auxiliary abutments is made of stacked lead plates, and the outer mold is made of polylactic acid fiber composite material; the inner skeleton of the main pile groups and auxiliary pile groups is made of aluminum alloy tubes, and the outer mold is made of polylactic acid fiber composite material and spliced ​​from arc-shaped parts; the inner skeleton of the main beam is made of steel, and the outer mold is made of wood.

[0019] As a further improvement to the aforementioned elastic scale model components of the deep-water cable-stayed bridge: In step 200, grooves are provided on the inner walls of the outer molds for the main pile group and auxiliary pile group. When the main pile group and auxiliary pile group require counterweight, lead sheets are placed in the grooves for counterweight, and then the inner wall of the outer mold is bonded to the outer wall of the inner frame. When the bridge tower and pier require counterweight, lead blocks are pasted onto the inner wall of the outer mold for counterweight, and the outer mold is connected to the inner frame after assembly. When the main bearing platform and auxiliary bearing platform require counterweight, the number of lead plates is adjusted for counterweight. The outer mold of the main beam has spaces distributed on both sides of the axial direction of the inner frame. When the main beam requires counterweight, lead blocks are placed in the spaces for counterweight. Therefore, the resulting three-layer mold structure of "outer mold-counterweight-inner skeleton" can precisely adjust the mass distribution of the model while maintaining similarity in stiffness and geometry, without changing the stiffness of the inner skeleton or affecting the geometric dimensions of the outer mold. In addition, the special installation method of the main pile group and the auxiliary pile group can also effectively prevent water from entering between the structural layers during the test and affecting the test accuracy.

[0020] The hydrodynamic testing method uses the aforementioned elastic scale model of the entire deep-water cable-stayed bridge and conducts the test in a fluid that satisfies the flow similarity criterion.

[0021] As a further improvement to the above-mentioned hydrodynamic testing method: the flow similarity criterion includes satisfying the velocity similarity ratio and the time similarity ratio; wherein, the velocity similarity ratio is derived from the Frod number similarity criterion, and the similarity ratio of the external geometric dimensions is used as the basis for the comparison. Represented as: The time similarity ratio is derived from the Strouhal number similarity criterion, based on the similarity ratio of external geometric dimensions. Represented as: Therefore, the velocity similarity ratio derived from the Frode number similarity criterion ensures that the ratio of gravity wave to inertial force in the model flow field is consistent with that of the prototype, and the time similarity ratio derived from the Strauhal number similarity criterion ensures that the ratio of fluid oscillation frequency to structural characteristic frequency is consistent with that of the prototype. The two work together to ensure the correct scaling of key parameters such as wave period, flow velocity and vortex shedding frequency in the experimental flow field.

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to aid in understanding the invention. The content provided in the drawings and their related descriptions can be used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 This is a schematic diagram of the structure of the elastic scale model component of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the outer mold of the bridge tower and pier in the elastic scale model component of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention.

[0026] Figure 3 This is a schematic diagram of the main pile group and auxiliary pile group in the elastic scale model component of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention.

[0027] Figure 4 This is a schematic diagram of the main and auxiliary abutments in the elastic scale model components of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention.

[0028] Figure 5 This is a schematic diagram of the main beam in the elastic scale model component of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention.

[0029] The relevant markings in the above figures are:

[0030] 110-Bridge tower, 120-Main pile cap, 130-Main pile group, 210-Pier column, 220-Auxiliary pile cap, 230-Auxiliary pile group, 300-Main beam, 400-Cable stay, 510-Outer formwork, 520-Inner skeleton, 610-Lead block, 620-Lead sheet, 630-Lead plate. Detailed Implementation

[0031] The present invention will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0032] The technical solutions and features provided in the various parts of this invention, including the following description, can be combined with each other without conflict.

[0033] Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0034] Regarding the terminology and units used in this invention: The terms "comprising," "having," and any variations thereof in the specification, claims, and related parts of this invention are intended to cover non-exclusive inclusion.

[0035] Figure 1 This is a structural schematic diagram of the elastic scale model component of the deep-water cable-stayed bridge for hydrodynamic testing according to the present invention. Figure 1 As shown, the model components of the elastic scale model of the entire deep-water cable-stayed bridge include the main tower pier foundation, auxiliary pier pile foundation, main beam 300, and cable stays 400; the main tower pier foundation includes the bridge tower 110, main abutment 120, and main pile group 130 distributed from top to bottom; the auxiliary pier pile foundation includes the pier column 210, auxiliary abutment 220, and auxiliary pile group 230 distributed from top to bottom.

[0036] The method for fabricating the elastic scale model components of the entire deep-water cable-stayed bridge includes steps 100-300, as detailed below:

[0037] Step 100: Determine the similarity ratios of various physical quantities between the model component and the original bridge component according to the geometric similarity criteria and the dynamic similarity criteria. The similarity ratios of various physical quantities include the similarity ratio of the external geometric dimensions, as well as the similarity ratios of mass, elastic modulus, moment of inertia, bending stiffness, cross-sectional area, and axial stiffness, expressed by the similarity ratio of the external geometric dimensions. Among them, the bending stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the moment of inertia similarity ratio, and the axial stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the cross-sectional area similarity ratio.

[0038] 1. Similarity ratio of external geometric dimensions

[0039] The geometric similarity ratio of the external shape is determined based on the geometric similarity criteria and the dimensions of the laboratory site, and is expressed as follows: .

[0040] 2. Quality similarity ratio

[0041] Assuming the fluid is incompressible, when the structure (model and original bridge) vibrates in the fluid, the fluid near the structure's surface vibrates along with the structure, and the hydrodynamic pressure effect of the fluid on the structure's surface must satisfy similarity. Therefore, in the model design, the fluid density similarity ratio is equal to the structural density similarity ratio. Since the experiment is conducted in water, the fluid density similarity ratio can be taken as 1; therefore, the structural density similarity ratio can also be taken as [value missing]. (That is, taking the equivalent average volume density of the model component and the original bridge component to be equal), thus obtaining the geometric similarity ratio of the structure. The mass similarity ratio is represented as .

[0042] 3. Elastic modulus similarity ratio

[0043] Based on the dynamic similarity criterion, and according to the dynamic equilibrium equation, geometric equation, and physical equation, an elastic-gravity similarity formula for the structure is established. Similarly, assuming that the equivalent average volume density of the model components and the original bridge components is equal, the elastic modulus similarity ratio is obtained as an expression of geometrical similarity. Taking the gravity direction as the x-axis, the horizontal transverse bridge direction as the y-axis, and the horizontal longitudinal bridge direction as the z-axis, the specific derivation process of the elastic-gravity similarity formula is as follows:

[0044] Dynamic equilibrium equations: ;

[0045] Geometric equations: , ;

[0046] Physical equations: , ;

[0047] In the formula, These are density, gravitational acceleration, elastic modulus, Poisson's ratio, and time, respectively. These are the stress similarity ratio, gravitational acceleration similarity ratio, density similarity ratio, time similarity ratio, strain similarity ratio, elastic modulus similarity ratio, and Poisson's ratio similarity ratio, respectively. These are the stress components along the corresponding axial directions; These are the shear stresses acting on the corresponding surfaces; The linear strain is along the x-axis. These are the displacement components along the corresponding axial directions; This represents the shear strain acting on the xy plane.

[0048] For all the above equations to hold true, the following constraints must be satisfied simultaneously:

[0049] ;

[0050] ;

[0051] ;

[0052] ;

[0053] ;

[0054] in, This indicates the similarity between the elastic restoring force and the inertial force in the dynamic equilibrium equations, and is referred to as elastic similarity. This indicates the similarity between gravity and inertial forces in the dynamic equilibrium equations, and is referred to as gravity similarity.

[0055] For the study of the dynamic response of bridge tower structures under wave action, both elastic and gravitational similarities can be considered simultaneously. It is known that gravitational acceleration satisfies... Combining the above formula The elastic-gravity similarity equation for the structure can be obtained as follows: .

[0056] Similarly, the equivalent average volume density of the model component and the original bridge component is taken to be equal, that is... Substituting the elastic-gravity similarity equation, we can obtain the geometric similarity ratio of the structure. The similarity ratio of the elastic modulus is represented as .

[0057] 4. Similarity ratios of moment of inertia, bending stiffness, cross-sectional area, and axial stiffness.

[0058] Under geometric similarity conditions, the similarity ratio of any purely geometric quantity depends only on the power of its length in its dimension. The dimension of the moment of inertia of a section is [l 4 ],so The dimension of cross-sectional area is [l 2 ],so .

[0059] The bending stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the section moment of inertia similarity ratio, and thus... , The similarity ratio of bending stiffness is obtained as follows: .

[0060] The axial stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the cross-sectional area similarity ratio. Therefore, according to... , The axial stiffness similarity ratio is obtained as follows: .

[0061] Step 200: Select materials and process them into model components that at least meet the similarity ratio of external geometric dimensions, bending stiffness, and / or axial stiffness; wherein, when the mass of the model component does not meet the mass similarity ratio with the corresponding original bridge component, the model component is counterweighted according to the difference between the mass of the model component and the scaled-down mass of the original bridge component.

[0062] To ensure structural elastic similarity, this invention proposes that it is not necessary to strictly maintain the geometric similarity of the cross-sectional shape of the members. Instead, a more flexible approach can be adopted, namely, maintaining the geometric similarity of the members in the length direction, relaxing the requirements for the cross-sectional shape, satisfying the geometric similarity of the cross-sectional shape by adding an external mold, and maintaining the similarity of the bending stiffness and / or axial stiffness of the cross-section by using internal reinforcement.

[0063] Therefore, for Figure 1 The elastic scale model of the deep-water cable-stayed bridge shown, except for the cable stays 400, the main tower pier foundations, auxiliary pier pile foundations, and main beams 300 all adopt an internal skeleton-outer mold composite structure. Material selection and processing are based on the internal skeleton meeting the similarity ratio of bending stiffness and / or axial stiffness, and the external mold meeting the similarity ratio of external geometric dimensions. Counterweights are added based on mass differences. Specifically, the bridge tower 110, main pile group 130, pier 210, auxiliary pile group 230, and main beams 300 are bending members. The internal skeleton's primary control index is meeting the similarity ratio of bending stiffness. The bridge tower 110 and main beams 300 simultaneously bear significant axial forces, and their internal skeletons must also consider the similarity ratio of axial stiffness when conditions permit. When the rectangular cross-sectional dimensions are uniquely determined by the similarity ratio of bending stiffness but cannot simultaneously and accurately meet the similarity ratio of axial stiffness, the similarity ratio of bending stiffness is the priority control index. The main pier cap 120 and auxiliary pier cap 220 are considered rigid bodies, and their internal skeleton stiffness should be sufficiently large to ensure overall rigidity. The 400-meter cable-stayed bridge is an axial component, and the material is selected and processed directly based on the similarity ratio of axial stiffness.

[0064] For example, the inner skeleton of the bridge tower 110 and pier 210 is made of steel, and the outer formwork is made of polylactic acid fiber composite material; the inner skeleton of the main bearing platform 120 and auxiliary bearing platform 220 is formed by stacking and fastening lead plates 630, and the outer formwork is made of polylactic acid fiber composite material; the inner skeleton of the main pile group 130 and auxiliary pile group 230 is made of aluminum alloy tube, and the outer formwork is made of polylactic acid fiber composite material; the inner skeleton of the main beam 300 is made of steel, and the outer formwork is made of wood.

[0065] Figure 2 This is a structural diagram of the outer formwork for the bridge towers and piers. (Example:) Figure 2 As shown, the outer mold 510 of the bridge tower and pier is assembled from U-shaped or arc-shaped parts; when counterweight is required, lead blocks 610 are directly pasted on the inner wall of the outer mold 510, and the outer mold 510 is tightly connected to the inner frame after assembly.

[0066] Figure 3 A structural diagram of the main pile group and auxiliary pile group. (Example) Figure 3 As shown, the outer mold 510 of the main pile group and the auxiliary pile group is assembled from arc-shaped parts; when counterweight is required, a groove is opened in the inner wall of the outer mold 510 and lead sheet 620 is placed in the groove for counterweight, and then the inner wall of the outer mold 510 is bonded to the outer wall of the inner bone 520 as a whole.

[0067] Figure 4 A structural diagram of the main bearing platform and auxiliary bearing platforms. (Example) Figure 4 As shown, the outer molds of the main support platform and the auxiliary support platform are distributed on the horizontal surface of the inner skeleton 520; when counterweight is required, the counterweight is adjusted by adjusting the number of lead plates in the inner skeleton 520.

[0068] Figure 5 A structural schematic diagram of the main beam. (Example) Figure 5 As shown, the outer formwork 510 of the main beam (the cover plate is not shown) has spaces distributed on both sides along the axial direction of the inner rib 520. When the main beam needs to be counterweighted, lead blocks 610 are placed and fixed in the spaces for counterweighting; after counterweighting, the cover plate is installed as the road surface.

[0069] To facilitate processing, the outer formwork of the bridge towers, piers, main pile groups, and auxiliary pile groups all adopt a segmented structure. Preferably, when installing each segment, a gap of 1 to 5 mm is maintained between each segment to eliminate the influence of the outer formwork on the structural rigidity.

[0070] Step 300 involves assembling the model components to obtain the flexible scaled-down model assembly. The preferred, but not limited to, assembly method is bolted connection and / or adhesive bonding. The stay cables are made of steel strands, with one end anchored to the main beam and the other end connected to the corresponding anchor point on the bridge tower via springs, thus simulating the actual stress state. A laser level is placed on the main beam, and then the cable clamps are released while the stay cables are manually dragged. When the laser level reaches a balanced state, the effect of a straight tower and level beam is achieved.

[0071] The specific implementation of the hydrodynamic test method of the present invention is to use the above-mentioned elastic scale model component to conduct the test in a fluid that meets the flow similarity criteria, wherein the flow similarity criteria are the velocity similarity ratio and the time similarity ratio.

[0072] Given that the similarity ratio of gravitational accelerations satisfies Similar to Freud's number The velocity similarity ratio can be obtained as follows: Further, due to the similarity of the Strauhal numbers... The time similarity ratio can be obtained as follows: .

[0073] The processing and counterweighting process will be described below through specific examples.

[0074] The original bridge towers were made of C55 concrete with a density of 2600 kg / m³. 3 Its elastic modulus is 35.5 GPa, and its volume is 4.93859 × 10⁻⁶. 12 mm 3 The mass is 1.28403 × 10⁻⁶. 7 The structure has a mass of kg and a height of 154 m. The vertical moment of inertia, lateral moment of inertia, and torsional stiffness of the cross-section are as follows: m 4 , m 4 , m 4 .

[0075] Based on geometric similarity ratio Constructing a scaled-down model of the entire deep-water cable-stayed bridge, the scaled-down bridge tower model is made of Q345 steel with a density of 7850 kg / m³. 3 The elastic modulus is 2.1 × 10⁻⁶. 11 Pa.

[0076] Based on the similarity ratio of bending stiffness It can be deduced From this, we can derive the vertical moment of inertia and the lateral moment of inertia of the bridge tower model section as follows: m 4 , m 4 Similarly, the torsional stiffness can be obtained. m 4 ;

[0077] The internal cross-section of the bridge tower model is rectangular. The formula for calculating the moment of inertia of a rectangular cross-section is as follows: Where b is the width of the cross section and h is the height of the cross section, the width of the cross section can be calculated as b = 0.01159m and the height as h = 0.02073m.

[0078] A bridge tower model with a width b = 0.01159m and a height h = 0.02073m was used in the finite element software Ansys to calculate the vertical moment of inertia and the lateral moment of inertia of the cross-section. m 4 , m 4 Torsional stiffness is m 4 The torsional stiffness deviation was 4.6%, indicating that the calculation method was correct.

[0079] Given the similarity ratio of the external geometric dimensions Quality similarity ratio Therefore, the height of the bridge tower model can be calculated as follows: The quality is .

[0080] Then, based on the endosteum mass... The mass of the outer mold is (Determined by on-site weighing) The required counterweight mass for the bridge tower model is calculated as follows: .

[0081] The counterweight calculation results for other model components are as follows:

[0082] Table 1 Calculation results of the main beam model configuration

[0083]

[0084] Table 2 Calculation results of the configuration of the main pile group (38 piles)

[0085]

[0086] The completed elastic scale model of the deep-water cable-stayed bridge was fixed on the foundation of the test site. Accelerometers were placed on the tower columns and crossbeams of the bridge tower model, and tests were conducted along the transverse direction using artificially excited hammer blows. The natural fundamental frequency of the bridge tower model was obtained by processing the experimental data using the FFT method. The natural fundamental frequency of the original bridge tower was obtained using the finite element analysis software Ansys. The results show that the deviation of the natural fundamental frequency between the original bridge tower and the bridge tower model is 3.6%, which is within 5%. It can be seen that the elastic scale model of the deep-water cable-stayed bridge produced by this invention can better reproduce the structural characteristics.

[0087] The foregoing has described the relevant content of the present invention. Those skilled in the art will be able to implement the present invention based on these descriptions. All other embodiments obtained by those skilled in the art based on the above description of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A scaled-down model of a deep-water cable-stayed bridge for hydrodynamic testing, characterized in that: The production method includes the following steps: Step 100: Determine the similarity ratios of various physical quantities between the model component and the original bridge component according to the geometric similarity criteria and the dynamic similarity criteria. The similarity ratios of various physical quantities include the similarity ratio of external geometric dimensions, as well as the similarity ratios of mass, elastic modulus, moment of inertia, bending stiffness, cross-sectional area, and axial stiffness expressed by the similarity ratio of external geometric dimensions. Among them, the bending stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the moment of inertia similarity ratio, and the axial stiffness similarity ratio is determined by the product of the elastic modulus similarity ratio and the cross-sectional area similarity ratio. Step 200: Select materials and process them into model components that at least meet the similarity ratio of external geometric dimensions, bending stiffness, and / or axial stiffness; wherein, when the mass of the model component does not meet the mass similarity ratio with the corresponding original bridge component, the model component is counterweighted according to the difference between the mass of the model component and the scaled-down mass of the original bridge component. Step 300: Assemble the model components to obtain the elastic scale model components of the entire deep-water cable-stayed bridge.

2. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 1, characterized in that: By assuming that the equivalent average volume density of the model component and the original bridge component are equal, a similarity ratio based on the external geometric dimensions is obtained. The mass similarity ratio is represented as .

3. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 1, characterized in that: Based on the dynamic equilibrium equations, geometric equations, and physical equations, an elastic-gravity similarity relationship is established. Taking the equivalent average volume density of the model component and the original bridge component as equal, a similarity ratio based on external geometric dimensions is obtained. The similarity ratio of the elastic modulus is represented as .

4. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 3, characterized in that: The similarity ratio of the moment of inertia of the cross section is ,according to , The similarity ratio of bending stiffness is obtained as follows: .

5. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 3, characterized in that: The cross-sectional area similarity ratio is ,according to , The axial stiffness similarity ratio is obtained as follows: .

6. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 1, characterized in that: In step 200, the model components include the main tower pier foundation, auxiliary pier pile foundation, main beam, and stay cables; among them, the main tower pier foundation, auxiliary pier pile foundation, and main beam adopt an inner skeleton-outer mold combination structure, and the materials are selected and processed according to the inner skeleton satisfying the bending stiffness similarity ratio and / or axial stiffness similarity ratio, and the outer mold satisfying the external geometric dimension similarity ratio.

7. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 6, characterized in that: The main tower pier foundation includes a bridge tower, a main pile cap, and a main pile group distributed from top to bottom; the auxiliary pier pile foundation includes a pier column, an auxiliary pile cap, and an auxiliary pile group distributed from top to bottom. The inner frame of the bridge towers and piers is made of steel, and the outer formwork is made of polylactic acid fiber composite material and is spliced ​​from U-shaped parts. The inner skeleton of the main support platform and the auxiliary support platform is made of stacked lead plates, and the outer mold is made of polylactic acid fiber composite material. The inner frame of the main pile group and the auxiliary pile group is made of aluminum alloy tube, and the outer mold is made of polylactic acid fiber composite material and is spliced ​​from arc-shaped parts. The inner frame of the main beam is made of steel, and the outer formwork is made of wood.

8. The elastic scale model component of the deep-water cable-stayed bridge as described in claim 6, characterized in that: In step 200, grooves are provided on the inner walls of the outer molds of the main pile group and the auxiliary pile group. When the main pile group and the auxiliary pile group need to be counterweighted, lead sheets are placed in the grooves for counterweighting, and then the inner wall of the outer mold is bonded to the outer wall of the inner bone as a whole. When the bridge towers and piers need to be counterweighted, lead blocks are attached to the inner wall of the outer mold for counterweighting. After the outer mold is assembled, it is connected to the inner frame. When the main bearing platform and auxiliary bearing platform need counterweight, the counterweight is adjusted by changing the number of lead plates; The outer formwork of the main beam has spaces distributed on both sides of the inner rib along the axial direction. When the main beam needs to be counterweighted, lead blocks are placed in the spaces for counterweighting.

9. A hydrodynamic testing method, characterized in that: The elastic scale model component of the deep-water cable-stayed bridge as described in any one of claims 1-8 was used to conduct tests in a fluid that satisfies the flow similarity criterion.

10. The hydrodynamic testing method as described in claim 9, characterized in that: The flow similarity criteria include satisfying the velocity similarity ratio and the time similarity ratio; wherein... The velocity similarity ratio is derived from the Frode number similarity criterion, based on the similarity ratio of external geometric dimensions. Represented as: ; The time similarity ratio is derived from the Strouhal number similarity criterion, based on the similarity ratio of external geometric dimensions. Represented as: .

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