Inelastic seismic response of buildings with passive energy dissipation devices

This thesis presents an analytical study aimed at evaluating the inelastic seismic performance of moment resisting frames (MRFs) retrofitted with different approaches. For this, a set of MRFs covering steel moment resisting frames (SMRFs) and reinforced concrete moment resisting frames (RC-MRFs) were studied. They were three regular four equal bay frame models having three different numbers of storeys (3, 6 and 12). The frames were considered to be representative of exterior moment resisting frames found in typical residential buildings. All frame models were designed with lateral stiffness insufficient to satisfy code drift and hinge limitations in zones with high seismic hazard. Three different retrofit strategies including traditional diagonal bracing system and passive energy dissipation devices such as buckling restrained brace and viscoelastic damper were utilized for seismic upgrading of the existing structures. In the nonlinear time history analysis, a group of ground motions indicating the design earthquake with 10% exceedance probability in fifty years was taken into account. Considering the local and global deformations, the analysis results in terms of plastic hinge formations, interstorey drift index, global damage index, roof drift time history, height-wise distribution of peak storey drift and base shear demand were compared. The results pointed out a considerable enhancement in the earthquake performance of retrofitted structures and it was shown that both buckling-restrained braces and viscoelastic dampers allowed for an efficient reduction in the seismic demands of the upgraded frames as compared to traditional braces.