Finite-Element Updating of the University of Exeter Forum Walkway

Abstract

This paper presents the finite element (FE) updating of a walkway, part of the University of Exeter’s Forum building. The walkway is a relatively slender structure with natural frequencies in the range that can be excited by human induced vibrations. It is often difficult for designers to model and predict as-built modal properties of such structures with an adequate degree of precision. Thus updating of their FE models is highly instructive for situations like this one. The aim of this paper is to assess the ability to predict accurately the modal properties of this particular structure and to correlate and update the initial FE model with experimental results. The initial model is made based on technical drawings and on best engineering judgement. However, comparing the natural frequencies and mode shapes of the FE model with experimental results, it was seen that the model needs to be updated to match the real structural properties (natural frequencies and mode shapes) as accurately as possible. After the updating, an FE model was obtained where the first five vibration modes were updated. The obtained properties are by no means a unique solution. However, they lead to a reasonable model of the walkway which more accurately represents its modal properties.