Structural Safety Evaluation Of Multi-span Swallow Arch Bridge Based On Site Test

Bridge which has obtained more and more special concern plays a very essential role in the road traffic,because its safety performance directly influences whether the traffic flow would be unblock or not.Arc bridge is one of the bridge has been widely applied in our country,as the traffic volume increased year by year and operating time increasing,the performance of the bridge structure gradually degraded,structure damage accumulation,therefore,the safe usage of Bridges has become the focus of the industry.In order to ensure smooth traffic and steady economic development,it is important to assess the safety of bridge.In this paper,a half through bridge in service was based on the engineering support of steel tube concrete arc bridge using Midas Civil to finite element analysis,the bridge through structure under vehicle load internal force envelope diagram,determine the position and the structure of the control section.Then according to the results of finite element analysis beforehand to organize and implement the field experiment,combining theoretical analysis and experimental data,on the bridge under static and dynamic load stress response of safety performance evaluation.Main conclusions:(1)under test load,the control section measuring point strain within the normal range,the basic area of steel pipe concrete arch foot in cracking condition,main arch rib in flexible working state,the stress condition of the whole bridge basic meet the design requirements;(2)the first three modes of the bridge are horizontal vibration,and the lateral stiffness is weak.(3)the measured frequency of the first two orders of the bridge is smaller than the calculated frequency,and the third order measured frequency is greater than the calculation frequency,which indicates that the overall dynamic performance of the structure is poor.(4)the coefficient of the measured impact of the secondary hole and middle hole of the bridge is greater than the theoretical value,which indicates that the coupling effect of the bridge is obvious,and the bridge surface is less smooth.