Cold‐formed steel‐framed gypsum partition walls (hereinafter referred to as partition walls) sustain the seismic damage induced by small story drifts. The impacts on the functional deterioration and monetary loss of buildings are enhanced in earthquake events where structural damages are limited. Although the boundaries of partition walls vary by location in a building structure, the existing studies assume a typical partition wall surrounded by a frame consisting of columns and girders. In particular, the vertical boundary members vary from a column, stud column, and wall panel. Our present work investigates the influence of the boundaries on seismic damage and fragility assessment of partition walls using an experimental dataset of cold‐formed steel‐framed gypsum partition walls with various boundaries obtained at an E‐Defense shake table on a four‐story steel frame. A damage mechanism model considering the deformation and rigid body motion of the partition walls and boundaries suitably explains the observed damage variations and underlying mechanisms. This study also presents the non‐negligible impact of boundaries on the fragility and expected repair time and cost model of the partition walls. The presented results are critical in providing references for the layout of partition walls, damage predictions, construction improvements, and repair strategy.

Studies on recent earthquakes highlighted that buildings with minimal structural damage still suffer from extensive damage and failure of nonstructural components. The dropping and damage of suspended ceiling systems, which typically consist of acceleration-sensitive nonstructural elements, resulted in lengthy functional disruptions and extended recovery time. This article experimentally and analytically examined the vibration properties of an integrated ceiling system considering the interactions with surrounding electrical equipment. The theoretical stiffness and corresponding frequency of electrical equipment were initially derived and then verified by subsequent vibration tests and numerical analyses. The seismic performance of the air conditioner (AC) was evaluated with different installment configurations based on design spectra and floor response spectra. Vibration tests of the suspended integrated ceiling system considering the interactions with surrounding equipment showed that the inclusion of peripheral constraints increased the first horizontal vibration frequency of the ceiling system by a factor of approximately 6. The natural frequencies of all components in the integrated ceiling system were almost identical, which was attributed to the coupled behavior between the ceiling panels and surrounding equipment, emphasizing the effect of interactions between adjacent components during dynamic analysis. Based on the above experimental investigation, an associated numerical model of the integrated ceiling system was created. Finally, corresponding parametric studies that included the interactions with surrounding equipment, reinforcing braces of ACs and strengthening members at the rise-up location between two elevations were performed. K E Y W O R D S integrated ceiling system, interaction, nonstructural components, vibration model, vibration test

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.