Study On Vehicle-bridge Coupled Vibration Of Long-span Curved Beam Bridge Under Random Traffic Flow

When vehicles drive across a bridge,it will cause bridge vibration,meanwhile the bridge vibration will cause vehicle vibration.Affected by external factors such as bridge deck unevenness,it will aggravate the vibration between the vehicle and bridge,which is called the vehicle-bridge coupled vibration problem.Such problems involve many interdisciplinary disciplines and fields such as bridge engineering,vehicle engineering,computational mechanics,etc.Compared with straight beam bridges,due to the influence of the radius of the curved bridge,the vehicle-bridge coupling vibration mechanism of long-span curved beam bridges is more complex under the action of random traffic flow,and the impact on bridge safety and driving comfort is particularly prominent.Therefore,it is of great scientific significance to conduct research on vehicle-bridge coupling vibration of long-span curved beam bridges under random traffic flow.However,existing related research has deficiencies in vehicle-bridge coupling vibration models,bridge safety evaluation methods under random traffic flow,and quantitative analysis of bridge driving comfort.How to calculate the dynamic response of bridges under random traffic loads,and then scientifically evaluate the safety of the structure and driving comfort,is a major challenge facing this research field.In view of the above problems,taking the long-span curved beam bridge as the research object,introducing the excitation influence of bridge deck unevenness,taking into account the vertical and horizontal effects,deriving and establishing a vehicle-bridge coupling vibration model of the long-span curved beam bridge with random traffic flow,On this basis,a vehicle-bridge coupling evaluation system was developed to study the safety and driving comfort evaluation methods of long-span curved beam bridges under random traffic flow.The main contents and conclusions are as follows:(1)Based on the principle of potential energy stationary value,combined with the mechanical coupling and displacement coordination relationship between the wheels and the bridge deck considering the cross slope,a random traffic flow-long-span curved beam bridge vehicle-bridge coupling vibration model considering the vertical and horizontal directions is proposed to provide a theory for subsequent program development.The MATLAB platform was used to compile the random traffic flow-vehicle-bridge coupling analysis system.Through comparison and analysis with the dynamic response data of simply supported beam r bridges and curved continuous beam bridges,the changing trends of various indicators were relatively consistent,and the relative amplitude errors were less than 6%.Finally,through the actual bridge test,the trend of the bridge deflection time history curve is relatively consistent with the calculated result,the relative error of the amplitude is 1.57%,and the maximum relative error of the first three natural vibration frequencies is 5.65%,which verifies the correctness of the method and procedure(2)Relying on the autonomous development of the bridge coupling power assessment system,the typical five-axis heavy truck model and curve bridge radius,bridge surface unevenness,driving speed,vehicle weight,vehicle suspension rigidity and damping the bridge Impact factor(Safety power assessment indicators for actual bridge testing)analyzed the bridge power response under the action of driving,and screened 5 sensitive factors design orthogonal test solutions.Sexual sorting,the maximum and minimum value factors of the bridge Impact factor is given.Finally,during the analysis of the variance,the significant A class is 0.05,and the significant factor of the scratch Impact factor is obtained by the bridge deck unevenness.The significant factor of the Impact factor is the unevenness of the bridge and the radius of the curve bridge.(3)Relying on the self-developed vehicle-bridge coupling dynamic evaluation system and based on the extreme value principle,a multi-objective screening method for calculating the bridge Impact factor under random traffic flow is proposed,that is,based on the bridge dynamic and static response data sets and time data sets,through multi-objective screening,the dynamic response extreme value data sets and time data sets of the bridge are obtained,the corresponding static response extreme value data sets is located and extracted,the bridge Impact factor data set is calculated,and the distribution law of the Impact factor is obtained through KS test and statistics.Finally,determine the reasonable value of the bridge deflection Impact factor under random traffic flow.(4)Relying on the self-developed vehicle-bridge coupling dynamic evaluation system and the multi-objective screening impact factor calculation method,the significance factor of the bridge impact factor and the important parameters of random traffic flow,vehicle weight and driving distance were used to conduct orthogonal experiments and stepwise regression,and the random calculation formulas for deflection,bending moment and torque impact factors of long-span curved beam bridges under general and dense running states,and comparative analysis with multinational specifications.The results show that the Impact factor calculated by the formula of this article is larger than the norms of China and Japan under the smooth and Aclass bridge deck.meanwhile get greater than the norms of different countries.Therefore,the deterioration of the bridge deck will exacerbate the vibration response between the vehicle and the bridge.It is recommended that subsequent management units strengthen the monitoring and maintenance of the conditions of the bridge deck.(5)The vehicle-bridge coupling vibration problem not only affects the safety of the bridge,but also affects the driving comfort of the bridge.Relying on the self-developed vehicle-bridge coupling dynamic evaluation system,this paper first proposes a vehicle acceleration data fusion method with time-varying dimension positioning integration;secondly,calculates long-span curved beams through an improved AHP-entropy weight method combined weighting method;finally,a driving comfort evaluation model of long-span curved beam bridge under random traffic flow in general and intensive operating conditions was established,achieving a quantitative evaluation of the driving comfort of long-span curved beam bridges under random traffic flow.The research results reveal the coupling vibration relationship between random traffic flow and bridges,improve the rationality of the value of bridge Impact factor under random traffic flow,realize the quantitative evaluation of bridge driving comfort,and provide safety monitoring and driving comfort for such bridges during service.It provides reference for performance evaluation and has important scientific significance and engineering application value.