Seismic response of six-story steel frame building with self-centering energy-dissipative (SCED) braces combined with linear viscous dampers

The self-centering energy-dissipative (SCED) brace is an innovative cross-bracing system that eliminates residual building deformations after seismic events and prevents the progressive drifting that other inelastic systems are prone to experience under long-duration ground motions. Previous studies of SCED braces have focused on the use of friction dampers as the primary energy-dissipating element within the brace. This study uses a six-story prototype building model to determine whether the addition of viscous dampers to the SCED-braced frame can efficiently reduce the accelerations while providing similar or better drift and base shear response. Two main design cases were studied: one with viscous damping only and one where viscous damping was combined with the friction damping within the SCED brace. The viscous damping constant at each story was calculated by determining the equivalent damping necessary to match the energy dissipation provided by a SCED brace with full friction damping at a design drift and modal frequency. The resulting hysteretic behavior of the structure was then modeled using the nonlinear structural analysis package OpenSees to determine the dynamic response of the structures. The best dynamic response was achieved by using 50% of the full SCED brace friction damping combined with viscous damping equivalent to the remaining 50% of the friction damping evaluated at the first modal frequency. This design resulted in a modest 15% increase in base shear while achieving significant performance improvements, decreasing accelerations by 30% and drifts by 20%