OPERATIONAL MODEL IDENTIFICATION AND CALIBRATION OF CFST ARCH BRIDGE BASED ON AMBIENT EXCITATION

To conduct the aseismic analysis of concrete-filled steel tube (CFST) arch bridges,the initial finite element model of a practical and operational CFST arch bridge is derived. Meanwhile,a more accurate and up-to-state dynamic analysis model for aseismic analysis can be derived through the modal identification and calibration techniques. Thus,this paper is to bridge the gap between the health monitoring techniques and aseismic analysis for large-span bridge structures. With the employment of the ambient response histories from a health monitoring system of this bridge,the operational modal parameters are identified by the FDD method,the FE model has been calibrated using a zero-order approximation method then. Results show that the FDD method can well identify the modal parameters and satisfactory results are observed in using the zero-order approximation method for the model calibration. The error between calculated and measured frequencies can be reduced to 0.11%~3.76%,and the variations of material properties (8.77%~10.21%) have significant effects on the structural dynamic behavior. The calibrated model,reflecting the practical state of a structure,can be used to assess the aseismic behaviors of operational bridge structures in the further.