A method for predicting the service performance of steel-concrete composite bridges
By constructing a long-term performance model of composite beams and dynamic equations of vehicle-bridge coupled systems, combined with a fatigue damage model, the problem of insufficient accuracy in predicting the service performance of steel-concrete composite bridges was solved, and accurate simulation of long-term deformation and vehicle-bridge coupled vibration was achieved, thus improving the accuracy of prediction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING JIAOTONG UNIV
- Filing Date
- 2026-05-15
- Publication Date
- 2026-07-31
AI Technical Summary
Existing technologies struggle to accurately predict the service performance of steel-concrete composite bridges, especially under the influence of complex factors such as long-term deformation and vehicle-bridge coupled vibration, resulting in insufficient prediction accuracy.
A long-term performance model of the composite beam is constructed. Combining the dynamic equations of the vehicle-bridge coupled system, considering interface slip and shear lag effects, the finite element model is optimized. Through the incremental method and fatigue damage model, the long-term deformation and dynamic response are calculated step by step, the damage results are corrected, and accurate prediction is achieved.
It enables accurate prediction of the service performance of steel-concrete composite bridges, effectively reflecting the effects of long-term deformation and vehicle-bridge coupled vibration, thus improving the accuracy and reliability of the prediction.
Smart Images
Figure CN122490927A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of bridge service performance prediction methods, and in particular to a method for predicting the service performance of steel-concrete composite bridges. Background Technology
[0002] Steel-concrete composite bridges have been widely used in modern bridge engineering due to their high material utilization rate, convenient construction, and superior structural performance. These bridges use shear connectors (such as studs) to combine steel beams and concrete bridge decks for coordinated operation; their long-term service performance directly affects the safety and durability of the structure.
[0003] Throughout a bridge's service life, its performance is subject to a complex interplay of time-varying factors. First, time-varying effects such as shrinkage and creep in concrete materials lead to significant long-term deformations (e.g., deflection) in the bridge structure. This long-term deformation is not static; it alters the bridge deck's alignment, thus affecting the dynamic response of vehicles traveling on the bridge. Second, moving loads such as trains induce vehicle-bridge coupled vibrations, generating dynamic effects and cyclic stresses within the structure. For these reasons, current predictions of the service performance of steel-concrete composite bridges lack sufficient accuracy. Summary of the Invention
[0004] The purpose of this invention is to provide a method for predicting the service performance of steel-concrete composite bridges, which can accurately predict the service performance of steel-concrete composite bridges.
[0005] To achieve the above objectives, the present invention provides a method for predicting the service performance of steel-concrete composite bridges, comprising: Construct a long-term performance model for composite beams that can calculate the long-term deformation of composite beams; Construct the dynamic equations of the vehicle-axle coupled system and calculate the dynamic response of the vehicle-axle system. Optimization of composite beam finite element model based on fatigue damage model; The service life of the composite beam is divided into multiple time steps. In the i-th time step, the long-term deformation is calculated, and the calculated deformation result is superimposed on the track irregularity. Then, the dynamic response of the vehicle-bridge system is calculated, and the damage is calculated based on the response result. The damage result is used to correct the composite beam model. Then, the calculation is performed in the (i+1)-th time step, and so on until all time steps are calculated.
[0006] The specific steps for constructing a long-term performance model of a composite beam capable of calculating its long-term deformation include: In the spatial domain, a refined model of a composite beam with 2 nodes and 18 degrees of freedom, considering interface slip and shear lag effects, is adopted. The composite beam elements discretized by the finite element method are assembled to form the dynamic equations of the composite beam subsystem. In the time domain, the time-varying effects of the composite beam are solved by the stepwise incremental method that does not require storing stress and strain history, resulting in a long-term performance model of the composite beam that can calculate the long-term deformation of the composite beam.
[0007] The specific steps for constructing the dynamic equations of the vehicle-axle coupled system and calculating the dynamic response of the vehicle-axle system include: Using the vehicle-bridge coupled dynamics method, the car body model adopts a 27-DOF classical model. The dynamic matrix of a single car body is assembled according to the train car number to construct the dynamic equation of the train subsystem. The dynamic equation of the train subsystem and the dynamic equation of the composite beam subsystem are combined through the wheel-rail relationship and the effect of track irregularities to construct the dynamic equation of the vehicle-bridge coupled system. In this process, the long-term deformation of the composite beam and the track irregularities are superimposed. Then, the Newmark-β method is used to solve the dynamic equation of the vehicle-bridge coupled system to calculate the dynamic response of the vehicle-bridge system.
[0008] The specific steps for optimizing the finite element model of the composite beam based on the fatigue damage model include: Based on the dynamic response results, the fatigue damage of the studs at different locations on the composite beam connection surface is calculated using a fatigue damage model. The calculation results are considered as the degradation of the shear connection stiffness of the studs, and the degraded stiffness values are corrected into the composite beam finite element model, so as to realize the influence of fatigue damage in the dynamic calculation of the vehicle-bridge system.
[0009] The present invention provides a method for predicting the service performance of steel-concrete composite bridges, which can accurately predict the service performance of steel-concrete composite bridges. Attached Figure Description
[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0011] Figure 1 This is a schematic diagram of a composite beam in the Cartesian coordinate system.
[0012] Figure 2 This is a diagram showing the cross-sectional dimensions and corresponding symbols of a steel-concrete composite beam.
[0013] Figure 3 This is a schematic diagram of the shear lag effect of composite beams, concrete slabs, and steel beams.
[0014] Figure 4 This is the front view of a 27-DOF train model.
[0015] Figure 5This is the left view of a 27-DOF train model.
[0016] Figure 6 This is the right view of a 27-DOF train model.
[0017] Figure 7 This is a spatial finite beam element model diagram of a steel-concrete composite box girder.
[0018] Figure 8 This is a schematic diagram of the normal wheel-rail contact interaction relationship.
[0019] Figure 9 This is the power parameter table for the CRH2 train.
[0020] Figure 10 This is a table of cross-sectional geometric dimensions for a composite box girder bridge.
[0021] Figure 11 This is a load condition table for a composite box girder bridge.
[0022] Figure 12 This is a flowchart of a method for predicting the service performance of a steel-concrete composite bridge according to the present invention. Detailed Implementation
[0023] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.
[0024] Please see Figures 1-12 This invention provides a method for predicting the service performance of steel-concrete composite bridges, comprising: S1 constructs a long-term performance model of composite beams that can calculate the long-term deformation of composite beams; The specific steps include: In the spatial domain, a refined model of a composite beam with 2 nodes and 18 degrees of freedom, considering interface slip and shear lag effects, is adopted. The composite beam elements discretized by the finite element method are assembled to form the dynamic equations of the composite beam subsystem. In the time domain, the time-varying effects of the composite beam are solved by the stepwise incremental method that does not require storing stress and strain history, resulting in a long-term performance model of the composite beam that can calculate the long-term deformation of the composite beam.
[0025] ψ c ( y ), ψ s ( yThese are the shear warping functions for concrete and steel beams, respectively (used to account for shear lag effects). The corresponding signs always represent the dimensional parameters of the bridge interface. Figure 2 There are annotations inside. Figure 3 This is the representation of the shear hysteresis function.
[0026] In the formula, for U-shaped steel beams, the top flanges and webs, due to their smaller width, do not exhibit shear hysteresis. ψ s ( y = 0; Due to the larger width of the bottom flanges, shear lag effect needs to be considered.
[0027] S2 constructs the dynamic equations of the vehicle-axle coupled system and calculates the dynamic response results of the vehicle-axle system; The specific steps include: Using the vehicle-bridge coupled dynamics method, the car body model adopts a 27-DOF classical model. The dynamic matrix of a single car body is assembled according to the train car number to construct the dynamic equation of the train subsystem. The dynamic equation of the train subsystem and the dynamic equation of the composite beam subsystem are combined through the wheel-rail relationship (vertical close contact, lateral creep) and the interaction of track irregularities to construct the dynamic equation of the vehicle-bridge coupled system. In this process, the long-term deformation of the composite beam and the track irregularities are superimposed. Then, the Newmark-β method is used to solve the dynamic equation of the vehicle-bridge coupled system to calculate the dynamic response of the vehicle-bridge system.
[0028] Generally, an excessively large γ will attenuate the higher-order frequencies of the structure, affecting the damping effect; an excessively small γ may cause calculation divergence and loss of stability. Therefore, γ is usually chosen to be 0.5. To further control analysis errors, there are also practical parameter combinations that satisfy the following formula to guarantee unconditional stability (this is the value selection rule for the Newmark β method): Therefore, β = 0.25 is usually chosen for general structural numerical calculation and analysis.
[0029] S3 optimizes the finite element model of the composite beam based on the fatigue damage model; The specific steps for optimizing the composite beam finite element model based on the fatigue damage model include: Based on the dynamic response results, fatigue damage of studs at different locations on the composite beam connection surface is calculated using a fatigue damage model (SN curve, PM cumulative theory). The calculation results are considered as the degradation of the shear connection stiffness of the studs, and the degraded stiffness values are corrected into the composite beam finite element model, so as to realize the influence of fatigue damage in the dynamic calculation of the vehicle-axle system.
[0030] Calculate the node slip Δ(x): N he Let be the shape function matrix corresponding to the slip displacement field function Δ(x) in the beam element. q he The element local nodal displacement vector corresponding to the slip displacement field function Along the length of the bridge, the longitudinal shear force borne by different shear studs: In the formula, For the beam element number; For the shear stiffness of the stud, This refers to the longitudinal shear force borne by a single row of studs.
[0031] Shear stress of the stud: In the formula, The number of bolts in a row. The diameter of the stud cross section.
[0032] The rainflow counting method was used for statistical analysis. During this process, stress amplitudes below 1 MPa were ignored because their contribution to fatigue damage was minimal. Then, the stress amplitude that the stud could withstand was determined using the SN curve. The maximum number of iterations. The SN curve of this invention is selected from Eurocode4, as shown in the following formula: In the formula, This represents the total number of cycles until structural fatigue failure. This represents the actual stress amplitude.
[0033] Throughout the bridge's service life, the fatigue damage of the interface studs is a cumulative process. When the accumulated damage reaches a certain level, the studs will fail. This invention, based on the Palmgren-Miner linear accumulation theory, calculates the damage to the studs at each stress amplitude using the formula above. Then, the damage from each stress amplitude is linearly accumulated to obtain the total fatigue damage of the studs. The accumulation formula is shown below: In the formula, D represents the total fatigue damage degree of the interface studs during service life, and n i Indicates stress amplitude The number of loops, N i To ensure that the stud can withstand the stress amplitude The maximum number of cycles; k is the total number of stress amplitudes of different values.
[0034] S4 divides the service life of the composite beam into multiple time steps. In the i-th time step, long-term deformation is calculated, and the calculated deformation results are superimposed on the track irregularities. Then, the dynamic response of the vehicle-bridge system is calculated, and damage is calculated based on the response results. The damage results are then used to correct the composite beam model. The calculation is then performed in the (i+1)-th time step, and so on, until all time steps are completed. The composite beam model mentioned in this step refers to the bridge model: first, a finite element model of the bridge is established using 2-node 18-DOF rod elements; then, the long-term deformation calculation method is added to the established model to obtain a long-term performance model. After each calculation, the bridge will experience damage, and the parameters of the bridge model are then updated.
[0035] Figure 10 This is a table of cross-sectional geometric dimensions for a composite box girder bridge. ρ sh =2kN / mm 2 These are parameters used in the actual design of composite beam bridges.
[0036] The present invention provides a method for predicting the service performance of steel-concrete composite bridges, which can accurately predict the service performance of steel-concrete composite bridges.
[0037] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of this application are still within the scope of this application.
Claims
1. A method for predicting the service performance of steel-concrete composite bridges, characterized in that, include: Construct a long-term performance model for composite beams that can calculate the long-term deformation of composite beams; Construct the dynamic equations of the vehicle-axle coupled system and calculate the dynamic response of the vehicle-axle system. Optimization of composite beam finite element model based on fatigue damage model; The service life of the composite beam is divided into multiple time steps. In the i-th time step, the long-term deformation is calculated, and the calculated deformation result is superimposed on the track irregularity. Then, the dynamic response of the vehicle-bridge system is calculated, and the damage is calculated based on the response result. The damage result is used to correct the composite beam model. Then, the calculation is performed in the (i+1)-th time step, and so on until all time steps are calculated.
2. The method for predicting the service performance of steel-concrete composite bridges as described in claim 1, characterized in that, The specific steps for constructing a long-term performance model of a composite beam capable of calculating its long-term deformation include: In the spatial domain, a refined model of a composite beam with 2 nodes and 18 degrees of freedom, considering interface slip and shear lag effects, is adopted. The composite beam elements discretized by the finite element method are assembled to form the dynamic equations of the composite beam subsystem. In the time domain, the time-varying effects of the composite beam are solved by the stepwise incremental method that does not require storing stress and strain history, resulting in a long-term performance model of the composite beam that can calculate the long-term deformation of the composite beam.
3. The method for predicting the service performance of steel-concrete composite bridges as described in claim 2, characterized in that, The specific steps for constructing the dynamic equations of the vehicle-axle coupled system and calculating the dynamic response of the vehicle-axle system include: Using the vehicle-bridge coupled dynamics method, the car body model adopts a 27-DOF classical model. The dynamic matrix of a single car body is assembled according to the train car number to construct the dynamic equation of the train subsystem. The dynamic equation of the train subsystem and the dynamic equation of the composite beam subsystem are combined through the wheel-rail relationship and the effect of track irregularities to construct the dynamic equation of the vehicle-bridge coupled system. In this process, the long-term deformation of the composite beam and the track irregularities are superimposed. Then, the Newmark-β method is used to solve the dynamic equation of the vehicle-bridge coupled system to calculate the dynamic response of the vehicle-bridge system.
4. The method for predicting the service performance of steel-concrete composite bridges as described in claim 3, characterized in that, The specific steps for optimizing the composite beam finite element model based on the fatigue damage model include: Based on the dynamic response results, the fatigue damage of the studs at different locations on the composite beam connection surface is calculated using a fatigue damage model. The calculation results are considered as the degradation of the shear connection stiffness of the studs, and the degraded stiffness values are corrected into the composite beam finite element model, so as to realize the influence of fatigue damage in the dynamic calculation of the vehicle-bridge system.