Seismic evaluation of two-elevation ceiling system by shake table tests

Past earthquakes highlighted the vulnerability of the suspended ceiling, especially in earthquake-prone countries like Japan; the post-earthquake reconnaissance showed that damage to ceiling systems led to immeasurable economic loss and disturbance of the timely rescue of casualty. The existing studies have mostly focused on the seismic performance of regular square and leveled ceilings, whereas the inevitable requirements to accommodate air ducts, nonstructural piping, and electrical equipment resulted in a two-elevation ceiling system. This paper reports a series of full-scale shake table tests on a typical two-elevation ceiling system, which includes electrical equipment, piping system, and commonly used suspended ceiling structure. Experimental observations showed that the two-elevation ceiling system performed well under earthquake excitation. No fallen panels or overall system collapse occurred during shaking. This paper discusses the effects of a temporary-positioning-bracing bar (TPBB) between two ceiling elevations and peripheral constraints by surrounding wall on the acceleration and displacement response and torsional behavior in the ceiling system. Then, a simplified analytical model was established and verified with the experimental response of different ceiling configurations. The test results indicated that a sufficiently strong TPBB is essential to reduce the relative displacement between two ceiling elevations, and it ensures the integrity of two ceiling elevations in the ceiling system. In conclusion, the TPBB shall remain in the ceiling system after the construction stage.