Modal Testing and FE Model Updating of a Lively Staircase Structure

Abstract

Effects of structural flexibility on the dynamic performance of structures such as staircases, footbridges, and long span floors is becoming an increasingly important aspect of modern design. Cost reduction, improving efficiency of design, enhancement of aesthetic perception and, innovation in architectural forms often result in slender and lightweight structures that are significantly more flexible and vibration-prone than ever before. Consequently, meeting relevant vibration serviceability criteria, as opposed to ultimate strength requirements, is becoming the governing factor in the design of many new structures. Despite significant advances in numerical prediction of modal properties of structures using Finite Element (FE) modelling technique, there still exist challenges in accurate representation of the actual dynamic behaviour. This is mainly due to some inherent modelling uncertainties related to a lack of information on the as-built structures, such as uncertainties in boundary conditions, material properties and the effects of non-structural elements. This paper presents the results of a modal testing exercise carried out to assess the dynamic behaviour of a lively staircase structure. The assessment procedure includes a full-scale ambient vibration testing, modal identification and FE modelling and updating. In particular, the influence of boundary conditions and presence of handrails on dynamic properties of the structure are commented.