Shake table tests for seismic assessment of suspended continuous ceilings

After an earthquake, the failure of suspended ceiling systems is one of the most widely reported types of nonstructural damage in building structures. Since suspended ceiling systems are not amenable to traditional structural analysis, full-scale experimental testing is planned and executed. In particular, shaking table tests are performed in order to investigate the seismic behaviour of plasterboard continuous suspended ceilings under strong earthquakes. Two kinds of ceiling systems, named single frame ceiling and double frame ceiling, are tested. A steel test frame is properly designed in order to simulate the seismic effects at a generic building storey. A set of five accelerograms, used as input for the shakings, are selected matching the target response spectrum provided by the U.S. code for nonstructural components. Three limit states (occupancy, damage and life safety limit state) are considered in this study in order to characterize the seismic response of suspended ceiling systems. The tested ceilings show no damage at all intensity levels, evidencing a low fragility. Three main aspects may be the cause of this low vulnerability: (a) the continuous nature of the tested ceilings; (b) the dense steel channel grid that supports the plasterboard panels; (c) the large number of hangers that connects the ceiling system to the roof, avoiding any vertical movement of the ceilings. Finally, an interesting comparison is made with a previous vulnerability study on a different typical U.S. ceiling system.