Finite element model updating of civil engineering structures: significance of mode shape paring

Abstract

Finite element models are created to describe the behaviour of the structure and predict its response to the loads to which the structure is subjected. Due to the basic assumptions of the finite element method, the behaviour predicted by the numerical model deviates from the actual behaviour. With the aim of reducing this deviation, the developed numerical model is calibrated through the process of model updating. This process is usually based on dynamic parameters such as mode shapes and natural frequencies. In this way, the residuals of the natural frequencies and modal shapes are defined, and their magnitudes are optimised. For this purpose, the modal assurance criterion is most used for mode shapes. The aforementioned criterion is most sensitive to large differences and relatively insensitive to small differences in the mode shapes. For this reason, this paper compares the application of different criteria to compare the mode shapes with the results of the model update of the laboratory model of a pedestrian bridge.