Shake Table Test Study And Analysis Of Extradosed Cable-Stayed Bridge

As a novel bridge type with good structural performance and economic indicators,extradosed cable-stayed bridge has been widely used at home and abroad.Since extradosed cable-stayed bridge becomes an important part of bridges in China,its seismic performance has become an important research content that needs to be paid attention to.However,current bridge seismic specifications worldwide are mainly applicable to small and medium span girder bridges.Only few contents of these specifications are provided for large span bridges like cable-stayed bridges,making it difficult to guide the seismic design of extradosed cable-stayed bridges with them directly.In this study,the shake table test and analysis researches are carried out for the extradosed cable-stayed bridge,and the main contents of this study are as follows:(1)Based on the related literatures,the development of extradosed cable-stayed bridges and the bright application prospect of them in China was firstly introduced.Then,current progress and existing deficiencies of researches on the seismic performance,earthquake damage characteristics and shake table test of extradosed cable-stayed bridges were systematically sorted out and summarized,respectively.In the end,the research purposes,main contents and technical routes of this study were clarified.(2)The design method of shake table test for the extradosed cable-stayed bridge was studied.A typical extradosed cable-stayed bridge with tower-pier-girder consolidation system was selected as the prototype bridge fot this test.Following the similitude theory,a large-scale full-bridge model of the prototype bridge was designed and constructed for the shake table test.The main ideas for the full-bridge model design and the specific design,construction and installation process of it were introduced,respectively.The layout of the measuring instruments and the scheme of the test were then provided.(3)The characteristic of seismic responses of the extradosed cable-stayed bridge were studied.In the longitudinal direction,different ground motion inputs were applied to the full-bridge shake table test model.The influence of different ground motion inputs on the seismic responses of extradosed cable-stayed bridges during the elastic stage were then discussed and summarized.(4)The longitudinal seismic damage development and failure behavior of the full-bridge test model was studied.The longitudinal destructive tests on the full-bridge test model were carried out using a set of ground motion inputs with increasing intensities.The damage characteristic of the extradosed cable-stayed bridge under strong earthquakes was discussed,and the seismic response test results of it were discussed.The variation law of seismic responses of the extradosed cable-stayed bridge during the elastic-plastic stage was further analyzed.The development process of seismic damage and the failure mode of the extradosed cable-stayed bridge excited by earthquake inputs with increasing intensities were summarized.(5)The finite element numerical simulation method of extradosed cable-stayed bridge was studied.Using the numerical simulation method,the structural dynamic analytical model of the full-bridge test model was established by OpenSees.Numerical analysis on the seismic responses of the full-bridge test model was carried out,and the simulation results were compared with the measured results of the shake table tests.Comparision results verified the accuracy of the numerical simulation results and the effectiveness of current numerical simulation methods.(6)A displacement calculation method for extradosed cable-stayed bridges based on elastic analysis was explored,and its validity was studied.Using the numerical simulation method,the natural vibration characteristics of the extradosed cable-stayed bridge and the distribution characteristic of its seismic bending moment,shear force and curvature response along the pier members were firstly studied.Then,the displacement calculation method of the extradosed cable-stayed bridge based on elastic analysis was explored.To verify the validity of this method,the prototype bridge was used as an example and different actual earthquake waves were selected as the ground motion inputs.Seismic responses of the prototype bridge under these actual earthquake waves were calculated using this method,and the calculation results of this method were compared with those of the nonlinear time history analysis method.In this way,the validity of this displacement calculation method for extradosed cable-stayed bridges based on elastic analysis was finally verified.