Seismic performance of suspended‐floor structures with viscous dampers considering acceptable interstory drift

Abstract

SummaryNumerical studies of suspended‐floor structures were conducted, and viscous dampers were applied to improve their seismic performances. The following issues were analyzed under 20 earthquake records: seismic responses of the primary structure and suspended floors, the distributions of the damping coefficient c0, and the interstory stiffness of the suspended floors. There was a significant reduction in the roof drift and the base shear force of the cores after replacing the steel bars with viscous dampers. The suspended‐floor structures with viscous dampers exhibited an optimal c0. The suspended‐floor structure with a triangular distribution of c0 showed a smaller seismic response than the one with a uniform distribution of c0. Under the design‐based earthquake, there was complete damage of nonstructural components in the y‐direction. Hence, applications of diagonal steel braces within the 1st to 10th floors were suggested to increase the lateral stiffness of the suspended floors in the y‐direction. The application of diagonal steel braces reduced the story drift Sd of the suspended floors, resulting in slight damage to nonstructural components under the design basis earthquake (DBE) hazard level. However, the roof floor, which contains electrical and mechanical components, exhibited an increase in Sd after the application of the diagonal steel braces. With increasing stiffness of the diagonal brace, the story drift profile of the suspended floors tended to be uniform, and the suspended‐floor structures with the uniform distribution of c0 exhibited seismic performances closer to those of the suspended‐floor structures with the triangular distribution of c0.