Seismic Performance Analysis Of Asymmetric Mixed Beam Cable-stayed Bridge

Earthquake is one of the natural disasters that lead to bridge damage.In recent decades,with the rapid development of economy and science and technology as well as continuous innovation in materials,new bridges have made significant breakthroughs and achievements in both span and material.As an important traffic structure connecting the two regions,it is worth studying whether the bridge can meet the criteria of large earthquakes,repairable medium earthquakes and good small earthquakes mentioned in China’s codes under the action of earthquakes.Asymmetric hybrid girder cable-stayed bridge has its unique static and dynamic characteristics and beautiful shape,which makes it an important transportation hub and key node project in many areas.Therefore,in order to ensure the safety and reliability of this kind of bridge under earthquake action,it is necessary to carry out seismic research.The response of bridge structure under earthquake is not only related to seismic waves,but also to the dynamic characteristics of the structure itself.The asymmetric hybrid girder cable-stayed bridge has its own particularity in material and structure.In order to reveal the response law of this kind of bridge under earthquake,and draw lessons from the existing research results at home and abroad,combined with an asymmetric hybrid girder cable-stayed bridge in a Northwest region,using Midas Civil 2015 finite element analysis software,the response spectrum method and time history analysis method are used to analyze the seismic response of this kind of bridge,so as to further understand the asymmetric hybrid girder cable-stayed bridge under earthquake action.Relevant work has been carried out as follows:(1)A spatial finite element dynamic model of an asymmetric hybrid girder cable-stayed bridge is established by using Midas Civil 2015 software.The pile-soil effect is considered by the "m" method,and the friction pendulum bearing is considered in the overall dynamic model.The dynamic characteristics of the bridge are calculated and analyzed.(2)The response spectrum method is used to calculate the seismic response of the structure under the action of response spectrum E1 and E2.Under the action of E1 and E2,the seismic response of each section under two kinds of excitations is obtained,i.e.constant load + longitudinal + transverse + vertical.The influence of vertical excitation on seismic response of structures is compared.The strength of structural piers under earthquake action is checked,and the displacement of structural supports is checked.The seismic response of the bridge is analyzed by using time history analysis method,and a time history analysis of uniform excitation seismic response for the seismic wave with the largest structural response is determined.The analysis results of response spectrum constant load + longitudinal + transverse + vertical excitation and time-consistent excitation are compared.(3)Considering the traveling wave effect,the non-uniform excitation is applied to the structure.The variation of displacement and internal force of each section is analyzed with the increase of wave velocity in the range of 0-250m/s.(4)The influence of friction coefficient and sliding curvature radius of friction pendulum bearing on seismic response of structure is analyzed by time history analysis method.According to the structural characteristics of this project,three reasonable bearing parameters are determined.Through the above analysis and research,I hope this paper can provide some reference significance and reference value for the seismic analysis of similar bridges in the future.