Seismic performance of direct hung suspended ceiling systems

Current seismic design philosophies require an earthquake-resistant building capable of resisting strong motion for structures and nonstructural elements. In response to the need to understand the seismic behavior of nonstructural elements, this paper presents the study on the vibration behavior and seismic capacity of direct hung suspended (DHS) ceiling systems. Modal analysis to investigate the eigen properties of the DHS ceilings was performed. Natural frequencies and mode shapes were identified using analytical models and verified by modal experiments. Different ceiling configurations were tested to understand their ultimate strength under incremental shock spectrum excitation. It was discovered that the 45° sway wires method prescribed by Ceiling and Interior System Contractors, does not increase the seismic capacity of the entire system. Based on recent field observations of DHS ceiling earthquake damage in Taiwan, it was found that pop rivets at the molding would increase the seismic capacity of the DHS systems. It was also discovered that a constraint transverse to the excitation direction would greatly influence the behavior of a DHS system.