Structural Finite Element Model Updating Using Ambient Vibration Test Results

Abstract

This paper presents a practical and user-friendly finite element (FE) model updating technique for real structures using ambient vibration test results. The first case study of a simulated simply supported beam demonstrates a comparative study of the influence of different possible residuals in objective function. Frequency residual only, mode shape related function only, modal flexibility residual only, and their combinations are studied independently. In view of tuning as well as damage localization, full objective function that considers all three residuals is the best for FE updating. This objective function is implemented in a second case study of a real concrete-filled steel tubular arch bridge. The bridge was tested by ambient vibration measurements. Followed by the three-dimensional FE modeling of the bridge, an eigenvalue sensitivity study is carried out to see the most sensitive parameters to the concerned modes. FE model mass matrix obtained from Guyan reduction technique is used to the mass normalization of the mode shapes extracted from ambient modal test to calculate the modal flexibility. The updated FE model of the bridge is able to produce a sufficient improvement on modal parameters of the concerned modes which is in close agreement with the experimental results still preserving the physical meaning of updated parameters.