Connectivity Reliability And Vulnerability Analysis Of Bridge Network Based On Beam Falling In Earthquake

In recent decades,earthquakes have brought enormous threats to human life and property,effective post-earthquake disaster relief can reduce the losses caused by earthquakes to the greatest extent.As a common form of damage in the earthquake,the falling beam is a very serious bridge disaster,when the beam falling occurs,the bridge will lose its function,and the repair is more difficult,which brings great difficulty to the disaster relief after the earthquake.This thesis is mainly aimed at the destructive form of beam falling,to analyze the vulnerability of the beam falling and to explore the influence of beam falling on road network connectivity reliability.The main research contents and conclusions are as follows:(1)To determine the index of beam falling and pier damage,in this thesis,the minimum shelf length of the beam end is used as the index of beam falling and the curvature ductility ratio is used as the index of bridge pier damage.The artificial seismic waves are generated by the target response spectra and then are input into the bridge model to obtain the seismic response of the bridge structure.(2)Using the seismic response of bridge structures to calculate the displacement difference between the main girder and the pier of the bridge,and establish the curve of the beam falling under earthquake,then compare the failure probability of the beam falling with the probability of damage to the pier in order to exploring the condition of the pier when the beam is falling.The results show that the failure probability of beam falling is between the severe damage and complete damage of the bridge pier,which is closer to the complete damage of the pier.(3)Taking four different bridge heights into consideration and discussing the vulnerability changes of bridges from the two factors of earthquake return period and pier height.The results show that these two factors have a certain impact on the vulnerability of the beam falling.(4)The damage of the beam falling is combined with the connectivity reliability of the road network,and the connectivity reliability curve of the network in different earthquake return periods is given.At last the impact on the connectivity reliability of bridge network which is caused by the changes of pier height is given.