Lateral Response of Older Flat Slab Frames and the Economic Effect on Retrofit

Abstract

Seismic retrofit schemes for older flat slab frames are commonly designed to carry the full design lateral loads, based on the assumption that the existing slab-column frame has low lateral stiffness and may fail in a brittle manner during earthquake loading. An experimental study was conducted to probe the actual response of a two story by two bay frame, and two isolated connection specimens, under cyclic lateral load reversals. The behavior observed indicated that for reasonable gravity loads, the lateral load response of these older slab-column frames is more ductile than anticipated. Therefore, structural engineers should be encouraged to utilize the strength and stiffness of the existing slab-column frame when designing a seismic retrofit system for the frame. Such a design will be less conservative, and thus less expensive, than is common in current design practice.