Collapse Analysis Of Continuous Girder Bridge And Quantified Study On Jugement Index Of Residual Deformation Based On IDA

According to the investigation data of past bridge disasters,a large number of bridges are directly collapsed under the action of earthquake,and some bridges which are not directly collapsed under the action of the earthquake will also have to be dismantled and reconstructed because of the excessive residual displacement of the pier top,so the study of the peak displacement and residual displacement of the pier under theearthquake action has great importance for seismic research of bridge.At present,there is no unified conclusion on the quantitative study of bridge structural collapse criteria,and it is necessary to make a thorough study of the quantification of the criteria for the collapse of continuous beam bridges.Based on this,this paper selects IDA method to study the seismic performance of a real RC beam bridge,the quantification criterion of the collapse of continuous girder bridge is explored in depth.In order to quantitatively study the damage degree of continuous beam bridge under earthquake action,a criterion for evaluating the damage degree of the drift rate of the column and the drift rate of the residual column is proposed.A practical continuous beam bridge is taken as the research object,the dynamic analysis model of the elastoplastic finite element is established by the Midas software and analyzed through IDA(Incremental dynamic analysis)method.In the seismic time-history analysis,the drift rate of the column is obtained by extracting the peak displacement of bridge pier under the action of different seismic waves,and the drift rate of the continuous beam bridge damage is given by the research results both at home and abroad.In this paper,the concept of residual cylinder drift rate is proposed and introduced to the judgement index of bridge collapse for the first time and also a new study direction for the bridge collapse,it's advantage to column drift rate is analyzed and its quantitative research is carried out,the recommended value of this paper is given finally.The main contents and work of this paper are as follows:(1)Analyzing and comparing the domestic and foreign research status of bridge collapse and synthesize the seismic analysis methods of existing structures,this paper mainly contrasts and analyzes the seismic analysis methods of three kinds of structures,and chooses the IDA method as the seismic analysis method in thispaper.(2)Synthesizing the existing selection principles of seismic waves and selecting the15 sets of seismic waves in turn,finally 10 seismic waves are chosed.According to the equal step amplitude modulation,the selected 150 seismic waves are modulated and usedto analyze the seismic response of structure by Midas;Analyzing the influence of the selection of IM and DM on the IDA curves,selecting IM and DM indicators which were suitable for this study by synthesizing the existing selection principles.(3)According to the result of the finite element analysis of the structure,theIDA curves are plotted by the peak displacement of the pier and the spectral acceleration;The proposed value of drift rate of column as the quantitative index of the bridge collapse criterion is obtained through analysis of IDA curves.(4)The time history curves of pier top displacement under various modulated seismic are obtained by Midas to get the residual deformation of the structure.T-he proposed value of the drift rate of residual column as quantitative index of bridge collapse criterion is obtained through IDA curves analysis after defining the drift rate of the residual cylinder and selecting the IM and DM indexes.The spectral accelerations corresponds to the different drifting rate of the column and the residual drift rate of the column is compared and the reasonableness of the residual column drift rate as the evaluation index of the structural collapse criterion isanalyzed.