Test And Analysis Of Stress Amplitude On Bridge Deck Structure Of Rail Transit Bridge

With the continuous increase of the scale of China's cities,the task of rail transit construction is getting heavier and heavier.Among them,the construction of large-span rail transit bridges is more and more,and steel bridges are mainly used.As far as bridge design codes are concerned,the regulations on the fatigue design of rail transit bridge steel structures are not comprehensive.This paper relies on the Chongqing Construction Science and Technology Project “Study on the Lateral Stiffness of Large-Span Urban Rail Transit Bridges and Fatigue Design of Steel Box Girder”,which mainly studies the real-time stress test and fatigue stress amplitude of steel bridge deck structures for rail transit bridges:(1)Through the large-scale bridge special finite element analysis software,the research-based project—the QianSimen Jialing River Bridge was modeled and static analysis was carried out,and the real-time stress test program plan of the bridge steel bridge deck structure was completed.(2)The real-time stress test of the QianSimen Jialing River Bridge on the 6th line of the urban rail line was carried out for six months,and the corresponding stress time-history curves of each fatigue control detail are obtained,and the results of different periods of operation are compared and analyzed.(3)The finite element model is used to analyze the dynamic response of the Qiansimen Jialing River Bridge and the JiaHua Track Special Bridge,and the fatigue stress time-history curve of the control fatigue details under different working conditions is formed.(4)Aiming at the QianSimen Jialing River Bridge,the load test research was carried out.The influence of the train's dynamic speed on the detailed stress time history of each fatigue control was investigated.The results of dynamic response analysis and load test were compared.(5)Through the rain flow counting method,the stress time history calculated by the finite element theoretical model of the QianSimen Bridge and the stress time history obtained after the stress test are statistically counted,and the corresponding variable amplitude fatigue is obtained.The stress amplitude and the number of stress cycles are treated according to Miller's fatigue cumulative damage criterion,which is equivalent to the normal amplitude fatigue stress amplitude and the number of actions.It is selected by the traditional fatigue life assessment method and according to the relevant specifications.A suitable S-N fatigue curve is obtained to the cumulative fatigue damage and residual fatigue life of the position of the fatigue control detail portion where the measuring point is located.The theoretical derivation results of fatigue life analysis of QianSimen Jialing River Bridge are fitted to the actual collected data processing results,and the obtained correction coefficient is used to correct the fatigue life analysis results derived from the fatigue control detail theory of JiaHua Track special bridge processed by the same method.