Application of a Comprehensive Seismic Retrofit Procedure for Steel Buildings Using Nonlinear Viscous Dampers

This study presents application of a new methodology to determine the characteristics of nonlinear viscous dampers (NLVDs). It also determines the optimum retrofitting level (ORL), by providing a novel and straightforward formulation without complex calculations. Inter-story drift ratio is considered as the effective parameter to calculate the failure cost of structures and to define limit states. To determine the ORL in low, medium and high-rise steel structures, three benchmark structures with different dynamic characteristics are studied. In addition, to validate the results in different zones with various seismic hazard levels, earthquake records representing three earthquake hazard levels are used in time history analysis. Based on the numerical results from nonlinear time history analyses, this comprehensive design procedure can be efficiently used to make seismic design of steel buildings with NLVDs, thereby meeting structural performance targets for any earthquake record at any intensity. Notably, use of the comprehensive design procedure reduces inter-story drift ratio to less than 0.7 in most building stories, suggesting that the building remains in immediate occupancy state under the applied earthquake records. Further, it can efficiently reduce the life-cycle costs and establish balance between the retrofit costs and failure reduction costs once structural retrofitting is performed.