The Influence Of Ground Motion Distortion Constant On The Vulnerability Of Long-span Cable-stayed Bridges

With the acceleration of the bridge construction process in my country,the construction and planning of long-span bridges is increasing day by day.In recent years,earthquake disasters have occurred frequently.As a lifeline project and an important part of the transportation network,long-span bridges will not only cause serious economic losses if they are damaged,but also will not be conducive to follow-up disaster relief personnel to take after the earthquake.Disasters relief and emergency rescue work have resulted in severe secondary disasters and even more serious economic losses.At the same time,a large number of earthquake damages indicate that the structure often undergoes rotation damage under the action of earthquakes.The rotation component of ground motion is one of the main factors for the rotation of the structure.The rotation component of the ground motion is simulated and the influence of the rotation component of the ground motion on the bridge structure is determined to reduce the structure.Torsion damage is a problem that needs to be solved urgently.The technical route of this paper is to firstly simulate the rotational component of ground motion,then select the appropriate engineering background,conduct numerical simulation and verify the accuracy of the model,and finally carry out the vulnerability analysis.The main research contents of this paper are as follows:(1)Establish the finite element model by using MIDAS.Based on the section and material properties provided by MIDAS,a finite element model of the same cable-stayed bridge was built through Open Sees.The basic dynamic characteristics of the two finite element models are analyzed and compared,and the accuracy of the model established in this paper is verified.The results show that the model established in this paper has high accuracy and can be used for subsequent vulnerability analysis.(2)15 groups of near-field pulsed ground motion were selected from the PEER ground motion database,and the rotational components of the corresponding ground motion were simulated based on the translational ground motion components using the elastic wave theory.In this paper,15 groups of ground motion torsion components are simulated,which lays a foundation for subsequent ground motion input.(3)Determine the damage index and damage state of the bridge studied in this paper.Based on the Latin hypercube sampling method in MATLAB,15 typical bridge samples considering the uncertainty of material parameters were established.To some extent,the influence of uncertainty is considered,which further improves the accuracy of vulnerability analysis.(4)According to the probabilistic vulnerability analysis method,the nonlinear dynamic time-history analysis of the bridge built in this paper and the drawing of the vulnerability curve are completed.By comparing the vulnerability curves of bridge members with and without ground motion torsion components,the influence of ground motion torsion components on the damage probability of cable-stayed Bridges is obtained,which provides a reference for the torsion resistance design of long-span Bridges.