Preliminary Study On Optimization Model For Predicting Seismic Damage Of Railway Girder Bridges

The seismic safety of lifeline infrastructure is critical to our nation’s earthquake prevention,mitigation,and disaster relief efforts.Railway bridges are even more important for the safety and stability of personnel and material transportation.The destruction of bridges in earthquake areas will directly hinder the implementation of earthquake relief operations,increase the loss of human lives and property,and cause indirect economic losses to society.It brings difficulties to the recovery and reconstruction work after the earthquake disaster.Meanwhile,most of the current bridge damage prediction methods are only applicable to highway bridges.Due to the lack of information on the earthquake damage of railway bridges,the research on the earthquake damage of bridges,especially the research on the earthquake damage prediction method of railway girder bridges,is still very incomplete.In addition,the earthquake damage prediction methods of highway bridges cannot be directly applied to the earthquake damage prediction of railway bridges.Therefore,it is of great practical importance to predict the earthquake damage of railway bridges.Based on the above,this paper formally launches a study on the current common methods of earthquake damage prediction of railway bridges at home and abroad.This paper summarizes the research status of various bridge damage prediction methods at home and abroad.Statistical data of earthquake damage in Tangshan earthquake and Wenchuan earthquake in China are presented.The main factors influencing the earthquake damage of railway girder bridges are analyzed and selected.Taking the development history of railway earthquake design codes and the completion time of railway bridges as the starting point,an optimization model for predicting the earthquake damage of railway girder bridges was established.Finally,the optimization model was back-evaluated and verified,and the feasibility of the optimization model was proved.This paper mainly accomplishes the following work:(1)Examples of seismic damage of bridge projects in the country and abroad over a century are presented.The influence of bridge seismic damage on the seismic research of bridge structures is classified and analyzed.The current development status and advantages and disadvantages of various bridge seismic damage prediction methods at home and abroad are presented.(2)The sixty-year development of seismic design codes for railway bridges in China is reviewed.The historical period of seismic design work of railway bridges in China is divided.The differences between different versions of seismic design codes for railway engineering in the section of railway bridges are compared and summarized.(3)The statistics of earthquake damage to railway girder bridges in the Tangshan and Wenchuan earthquakes are presented.The main factors influencing the damage caused to the superstructure,bearings,and substructure of railway girder bridges in earthquakes are studied.And the time factor is taken into account,with the development of the seismic design codes for railway engineering and the time of completion of railway bridges as the starting point,taking into account the changes in the seismic design conditions and the differences in the time of completion.Ten main factors affecting the seismic damage of railway girder bridges are identified.(4)An optimization model for earthquake damage prediction based on statistical methods is developed.Through statistical regression,the fitting coefficients of the optimization model and the regression and suggested values of different seismic impact factors are given.The optimization model is then back-evaluated and validated.A comparison with the Zhu Meizhen method is made to demonstrate the feasibility of the optimization model.