Model Updating of Long Uniform Buildings with Expansion Joints

Abstract

In the SHM framework, model updating procedure is an iterative or cyclical process which gives numerical model of structure having modal behaviour close to the dynamic behaviour of real structure. Normally for structures with or without any expansion joints typical model updating procedure is used. But the typical procedure may not be applicable for long uniform buildings having expansion joints since the individual blocks in structure connected with expansion joints tend to vibrate in coherence and this behaviour is confirmed by observing the identicalness of modal frequencies and similarity of mode shapes of individual blocks in long uniform buildings. This phenomenon was observed in three selected long uniform buildings. When structures connected with expansion joints vibrate in coherence or when the modal frequency of the connected structures are identical, the numerical models of these structures cannot be updated using typical procedure for the following reasons: newline1 Modal parameters from Modal identification of structure doesnâ t represent the actual parameters of the individual block since the ambient vibration is not independent and is influenced by interaction between blocks. newline2 Modal analysis of analytical model of individual structural blocks gives dynamic parameters which are true to the model. Therefore, these two sets of parameters canâ t be compared for convergence in model updating procedure. newlineTo overcome these issues regarding updating the numerical model of long uniform buildings with expansion joints, a different approach is proposed where instead of using modal parameters from analytical analysis, the parameters obtained for the structure from modelled floor responses to weak earthquake using FDD algorithm are used for checking convergence in model updating procedure. An attempt is made to update three selected long uniform buildings in which the coherence phenomenon was observed by applying the proposed procedure. newline