Dynamic performance assessment of a multistorey timber building via ambient and forced vibration testing, continuous seismic monitoring and finite element model updating

The Nelson Marlborough Institute of Technology Arts building is the world's first commercial implementation of a post tensioned Laminated Veneer Lumber (LVL) shear wall system based on EXP AN technology. Full-scale, in-situ dynamic testing and monitoring of the building was combined with finite element modelling and updating to obtain an understanding of the structural dynamic performance within the linear range. Ambient testing was performed at three stages during construction and was combined with forced vibration testing for the final stage. System identification was also performed using dynamic data from the continuous monitoring system. The results show that addition of non-structural elements, such as cladding and staircase, increased the natural frequency of the first and second mode by 19% and 24%, respectively. The addition of the concrete floor topping as a structural diaphragm significantly increased the natural frequency of the first mode but not the second mode, with an increase of 123% and 18%, respectively. Damping ratios of the building were between 1.6% and 5.2% and depended on vibration amplitude. Using FEM simulations, the maximum deflection for a 25 year return period seismic event was estimated to be 8mm.