Seismic Design Procedure for Total Accelerations and Inter-Story Drifts Reduction of Existing and New Buildings with Protective Systems

The new approach of Performance Based Design motivates the development of new methods for seismic retrofitting while two of the main performance indices are based on peak inter-story drifts and peak total accelerations. Previous research (Viti et al., 2006) has presented the concept of designing weak structures, or weakening some connections in existing structures, in addition to the installation of added viscous dampers. The new approach has been shown to effectively lead to relatively small drifts and accelerations. This paper presents a practical analysis based approach for the design of retrofitting of structures by weakening and damping. Alternatively, the algorithm can be used for the design of new structures equipped with viscous dampers to result desired levels of inter-story drifts while reducing total accelerations as well. The values of yield forces and damping coefficients serve as design variables. The physical behavior of yielding structures equipped with added viscous dampers is first analyzed and some insight to the strength and damping effects is gained. This insight is used to formulate simple intuitive criteria for the design that are then used to formulate a design procedure.