Seismic retrofit of r.c. frames with hysteretic bracing systems
Reinforced concrete structures built in seismic zones before 1960's were designed to resist mainly gravity loads and wind. The main deficiencies in reinforced concrete gravity frames are related to poor detailing and lack of capacity design, leading to reduced local and global ductility. At present, when such type of structures are subjected to structural evaluation, according to modern seismic design provisions, one finds out, that in almost all cases strengthening is needed. In present paper the strengthening of non-seismic r.c. frames with dissipative bracing system is examined. A detailed study case for a r.c. frame, designed according to provisions of 1950's and strengthened with steel Buckling Restrained Braces according to modern seismic provisions is presented. © 2007 Taylor & Francis Group.