Detecting structural changes with the one-step FE model updating technique

Differently from the sensitivity based finite element (FE) model updating technique in which the discrepancies between the FE and experimental modal properties are reduced iteratively by modifying the FE modelling assumptions, the one-step FE model updating technique based on modal orthogonality and the local correspondence (LC) principle updates the FE model in a single step. When updating an FE model with the one-step updating approach, it is assumed that the discrepancies between a FE model and the (physical) modelled structure are small and distributed over the model's degrees of freedom. If this assumption is fulfilled, it is verified that the one-step method efficiently updates the FE model, so that its modal properties match very well the ones obtained from experimental vibration tests. In this paper, the performance of the one-step updating technique in detecting localized changes is investigated by means of a practical application example in which the experimental modal properties of a t-shaped steel structure are used to update the corresponding FE model.