Risks from the response of non-structural components to seismic loads in buildings

This paper addresses the risks of failure of non-structural components (NSC) in buildings in future earthquates. Non-structural components are classified into (I) mcechancial components (e.g. boilers, tanks, pumps, and HVAC equipment), (II) Electrical and electronic components (e.g. transformers, generators, switchboards, computer networks, telecommunication systems and other electronic components) and (III) Architectural components (e.g. exterior curtain walls and cladding, non-loading bearing partitions, ceiling systems and ornaments such as marquees and signs). Failures of NSC could have severe life-safety and economic consequences which include damage caused by the overturning and falling of objects, and the loss of continous functioning of key facilities. Floor-mounted or freestanding components with behaviour sensitive to the floor motions are of particular interest in this paper. Thus, damage to components resulted from inter-story drifts are outside the scope of the discussions. This paper presents results of a recent field survey conducted by the authors ona range of building facilities in the Melbourne Metropolitan area. The survey highlights the fact that many critical NSC and potentially vulnerable to seismically induced damage due to the general lack of restraints. Simple analytical tools have been developed for the vulnerability assessment of the NSC, which are at risk. The assessment involves modelling the floor motions in terms of its peak response acceleration, velocity and displacements for any given earthquake motion affecting the building. This broadbank approach to modelling is an innovative departure from the conventional approach of merely addressing accelerations. This paper also provides a brief description of a planned shaker-table testing program for studying the fragility of some floor-mounted components.