Research On Simulation Analysis And Assessment Method Of Tied Arch Bridge Under Customized Transport Vehicle Load

With the vigorous development of large cargo transportation industry,the frequency of customized transport vehicle(CTV)passing bridges has also increased.Tied arch bridges are widely used in highway bridges.The dynamic simulation of the tied arch bridge under the CTV and rapid evaluation of the tie arch bridge for the passage of large transport vehicles are the keys to ensuring the safe passage of vehicles.At the same time,the composition of the tied arch bridge is diverse,and the characteristic of fatigue damage of the suspender should also be focused on.In view of the above problems,the following research has been carried out: Firstly,based on BDANS software,the coupling vibration analysis system of CTV-tied arch bridge was developed,and the spatial response characteristics of tied arch bridge under CTV were analyzed.Then,the fatigue reliability of the boom system was evaluated.Finally,based on the premise of the safety and security of the bearing capacity of the components and the system,the evaluation method of the tied arch bridge for the passage of CTV was established.The main research contents are as follows:(1)Aiming at the shortcomings of the current performance simulation of the tied arch bridge of CTV,by solving the key problems such as vehicle dynamic model establishment,tied arch bridge finite element simulation,road surface roughness simulation and the construction of vehicle-bridge coupling relationship,a coupled vibration analysis system of tied arch bridge under CTV was established,and a tied arch bridge was used as an example to verify the accuracy of the analysis system.(2)Taking a tied arch bridge with a span of 115 m as the engineering background,the dynamic response extremums of five typical CTV and design vehicles were calculated and compared.Subsequently,the relationship between the impact coefficient and the road roughness level,vehicle speed and vehicle quality were studied.(3)To solve fatigue reliability evaluation of suspender system under mixed traffic flow,firstly,based on the BDANS analysis system,the stress time history of the boom system under mixed traffic flow was obtained,and the corresponding fatigue stress spectrum was analyzed.Then,the limit state equation was established according to Miner ’s rule,and the probability distribution of the equivalent stress value and the total number of stress cycles in the specified time block was clarified by means of probability statistics and hypothesis test.Considering the influence of different traffic densities,the fatigue reliability evaluation of the boom system was realized.(4)Facing the need for rapid assessment of CTV through the tied arch bridge,firstly,the target reliability index of safety assessment was defined based on the equivalent method of annual failure probability.Secondly,the equivalent normal method was used to evaluate the safety of the component level,and the representative failure mode of each component was defined,and the probabilistic network estimation technique(PNET)method was used to evaluate the security of the system level.Finally,the safety evaluation method of tied arch bridge under large transport vehicle was established by using the critical effect ratio,and an example was analyzed.