Effect of non-structural components on natural frequency and damping of tall timber building under wind loading

Short-term ambient vibration testing (AVT) was carried out on two tall timber buildings (TTBs) at different construction's stages. The objectives of these tests were to evaluate key dynamic properties (natural frequencies and mode shapes) under predominantly ambient wind dynamic loading. The identified key dynamic properties were estimated experimentally for construction stages with and without non-structural façade and internal full-height partitions. Moreover, representative finite element (FE) models of both TTBs were developed using ANSYS software. The FE models were first developed using best engineering judgement and current practice which neglects the stiffness of the non-structural partitions. They were compared with the experimental results from the early construction stage where partitions were not present in the as-built structure. Then, the FE model enhanced by adding the façade and partitions which were first modelled as additional mass with no stiffness and then as additional mass with stiffness. It was found that the non-structural façade and partitions add not only mass but also significant amount of additional stiffness to the real structure. By updating the FE model to match the measured modal properties of the first three modes of vibration, a method is presented, which was considered the practical FE modelling of this additional stiffness via shell elements representing the façade and partitions paper.