Updating of Finite Element Models

A new optimisation method to find the global minimum of a cost function, named Coupled Local Minimisers (CLM), is presented. In CLM, several local optimisation processes are coupled, i.e. they interact and exchange information, resulting in better solutions than multi-start local optimisation with independent runs. The principal idea of CLM is worked out and illustrated with a mathematical test function, on which successful optimisation runs are carried out. Next, CLM is applied to finite element (FE) model updating. FE models of civil engineering structures are updated by minimising differences between experimental and numerical modal data, i.e. natural frequencies and mode shapes. The former reflect the global dynamic behaviour and can be measured quite accurately, the latter contain local information but the measured values are more noisy.