Seismic Upgrade of Existing Buildings with Fluid Viscous Dampers: Design Methodologies and Case Study

Abstract

Existing structures may be in need of seismic upgrading owing to structural deterioration, change in function or use, increased performance requirements, or modified seismic codes. In recent years, fluid viscous (FV) dampers have received increasing attention because of their notable seismic-reduction capacity and easy installation. This paper outlines the design procedure of seismic upgrading of existing buildings using FV dampers. Discussions are made on some key issues for seismic upgrading using FV dampers, including the analytical damper-brace model under large earthquakes and strategies for damper layout. A case study is made, in which a 21-story hotel built in 1991 was seismic upgraded. One special feature of this project is that only the first six stories can be structurally modified, resulting in limitations on the damper layout. According to the proposed design procedure, 56 FV dampers are suggested for this project, which provide a supplemental damping ratio of 5.3%. As a result, the seismic responses of upper stories could be significantly reduced, which avoids damaging the decoration of the building above its sixth story and enables short and economic construction.