Study On Long-span Bridge Operation Status Evaluation Based On Health Monitoring Data

As various long-span bridges are continuously built and put into operation,they will strongly promote economic development and bring convenience to people's lives,and at the same time bring great pressure on bridge management.The inspection and inspection of conventional bridges is difficult to understand the safety status of the bridge in time.The data transmitted in real time through the health monitoring system can timely and effectively evaluate the health status of the bridge structure in the operational state.Based on long-term monitoring data,the performance of the long-span bridge structure in operation can be evaluated,which can provide reliable support for the decision-making maintenance personnel of the bridge.This paper has done the following research with the cross-sea bridge as the engineering background:(1)By using the local mean decomposition(LMD)trend term extraction method based on spline interpolation,the temperature load and the deflection caused by the vehicle load are separated from the deflection component of the main beam,and the correlation between temperature and deflection is analyzed.For the deflection caused by temperature,the uniform variation model is used to calculate the long-term deflection score;for the deflection caused by the vehicle load,the non-uniform variation model based on the grey theory is used to calculate the long-term deflection.Through the longterm deflection score,the situation of the main beam deflection under normal operating conditions is evaluated,and the effective feedback of the overall health status of the bridge is obtained in time.(2)According to European norm 3(Eurocode 3)and Palmgren-Miner linear accumulation damage theory,the rain time counting method is used to calculate the stress time history and obtain the corresponding stress amplitude and stress cycle number statistics,according to the equivalent fatigue principle.The amplitude of the amplitude is converted into the constant amplitude and the corresponding number of cycles.The details of the steel box orthotropic bridge deck subjected to the variable amplitude stress cycle are classified and the fatigue life is evaluated.(3)Based on the measured vibration data of the cable,the MATLAB programming software is used to write the fundamental frequency automatic recognition algorithm based on the peak method to automatically identify the fundamental frequency of the cable vibration.Considering the influence of cable sag effect and bending stiffness,the cable force of the bridge cable is calculated,and the normal working state of the cable is monitored by comparing the cable force with the cable tension,the allowable cable force and the cable force.to evaluate.The analysis shows that there are three cables in the South Channel Bridge whose vibration is in an abnormal state during the rain and vibration.It is suggested that the three cables should be strengthened to prevent wind and vibration.