Vulnerability Analysis Of Half-through Steel Box Basket Arch Bridge

As the isolation technology matures,more and more researches and applications of high conversion isolation structures are carried out.However,most of them are based on single isolation form for transfer floor structure,and lack comparative analysis of different isolation forms.Aiming at the above problems,Midas Gen software is used to build different isolation forms of finite element analysis models and conduct the seismic time history and static elastic-plastic analysis in this paper.This has reference significance for seismic isolation design of the high conversion layer structure,which is combined with the results of effects of different isolation forms on the anti-seismic performance of the high conversion layer structure,The main contents of this paper are summarized as follows.(1)According to interlayer displacement responses of conversion layer structure on different floors under earthquake action,the mutation of displacement between layers of lower substructure of the high conversion layer structure is illustrated.The coefficient of substructure interlayer displacement angle is defined,and the mutation degree of substructure interlayer displacement angle of the high conversion layer structure is described.(2)The analysis of response spectrum and elastic-plastic seismic time history of each working condition model is carried out.By adjusting the input angle of seismic wave,the influence of stiffness ratios of different upper and lower structures on isolation is compared.The results show that different types of isolation can effectively control the displacement and interlaminar shear responses for a high-rise beam conversion layer structure.When the basic isolation is adopted,problems of high conversion layer structure being under conversion layers and mutation of substructure interlayer displacement angle can be effectively improved.When seismic bearing is arranged between the third layer and transition layer,mutation of substructure interlayer displacement angle and interlaminar shear of isolation layer may be more severe.(3)Based on the static elastic-plastic analysis of the anti-seismic and isolation models,all the performances of the high conversion layer structure before tumble and plastic hinge development of every component of structure are investigated,and the weak links of structure under various conditions are found.According to the capacity spectrum method,the performance points of every working condition structure under rare earthquake action of eight degree are confirmed,and the distribution of plastic hinge of various working conditions is obtained.(4)Earthquake vulnerability analysis based on inter-layer displacement angles is performed under four working conditions.Based on the responses of maximum inter-layer displacement angle of the structure under earthquake effects of different acceleration peaks,the parameters of the structural vulnerability function are determined.The seismic vulnerability curves of every working condition are obtained.Probabilities of different damage levels of structure for every working condition under earthquake action are calculated.