Fatigue performance analysis and evaluation for steel box girder based on structural health monitoring system

Abstract

Taizhou Yangtze River Bridge as a long-span suspension bridge, the finite element model (FEM) of it is established using the ANSYS Software. The beam4 element is used to simulate the main beam to establish the "spine beam" model of the Taizhou Yangtze River Bridge. The calculated low-order vibration mode frequency of the FEM is in good agreement with the completion test results. The model can simulate the overall dynamic response of the bridge. Based on the vehicle load survey, the Monte Carlo method is applied to simulate the traffic load flow. Then the overall dynamic response analysis of FEM is carried out. Taking the bending moment of the main beam as the control index, the fatigue sensitive section in the steel box girder of FEM is analyzed. Based on the strain time history data of steel box girder recorded by the structural health monitoring system (SHM), the true stress response of steel box girder under vehicle load is extracted. Taking the cumulative fatigue damage increment as the evaluation index, the fatigue performance evaluation of the steel box girders is conducted based on the collected health monitoring data. The fatigue effect of the beam section near the steel tower, especially the first section of the middle tower, is the key section of the fatigue analysis by health morning system, which is consistent with the calculation results of FEM.