An application of precast hybrid moment-resisting frames for seismic improvement

This paper presents an application of precast, hybrid, moment-resisting frames for improving the seismic safety of a standard five-storey residential building with a gravity-loaded, cast in situ reinforced concrete beam-column frame system. The non-linear mechanism of this new system is mainly governed by the opening and closing of discrete gaps at the interfaces of precast members. The improvement involved several research and development components, including quasi-static reversed cyclic loading tests, capacity design of hybrid frames, seismic performance evaluation of the entire building system using non-linear dynamic analysis, and cost comparisons of the original and proposed hybrid systems. Excellent seismic performance was demonstrated using each hybrid joint type; their force-deformation responses exhibited ductile stable hysteretic loops for up to 6% drift levels without severe damage. The hybrid frame building can withstand strong ground shaking (peak ground acceleration of 0.50g) without collapsing at minimal increased total cost (16.6%) compared with the cost of the original building.