Seismic Retrofit of a High-Rise Steel Moment Resisting Frame Using Fluid Viscous Dampers

The Pacific Earthquake Engineering Research (PEER) Center has expanded its Tall Building Initiative project to include the seismic performance of existing tall buildings. A candidate 35-story steel building with representative details from that era was analyzed. Pushover analysis and nonlinear dynamic response history results for the as-built building are discussed in a companion paper. In this paper, a potential retrofit approach using viscous dampers is presented. The performance criteria for the retrofit focused on reducing story drifts and accelerations to promote continued occupancy in moderate earthquakes. The retrofit feasibility study starts by selecting damper locations within architectural constraints. The overall effective damping ratio is calculated in order to satisfy a target roof drift limit based on the pushover analysis of the existing building. Three conventional damper placement methods are proposed, and the structural responses including story drift ratio, floor acceleration, and damper responses are compared. Possible improved schemes are investigated taking into account of performance-related and cost-related factors. In the end, a refined damper design scheme is proposed based on an overall cost-benefit analysis.