Seismic Retrofit Of Precast Panel Buildings In Sofia

Throughout the years earthquakes are a huge concern for structures;causing losses of people s' lives,damages and collapse of homes.Usually,most of the buildings that coll apse or have serious damages are mostly old buildings that do not fulfil any longer the updated regulations and building codes concerning seismic design.Many countries in Europe,especially ones from the former Soviet Bloc,are facing a potential crisis r egarding their deteriorating precast RC concrete panel residential buildings.These complexes were built using industrial methods in response to the housing shortage during the 1960 s,70s and 80 s.An ending life-cycle in combination with the poor design and construction quality makes these existing buildings highly vulnerable to earthquakes that are frequent in the region.In this study addresses the need to act urgently in order to retrofit these existing structures and ensu re that they meet today's build ing code requirements.It is achieved through a case study that explores the effectiveness of global bracing seismic mitigation techniques on an existing precast panel building located in Sofia,Bulgaria.The in-situ building is first analyzed using SAP200 0 and then again after the bracing is added to the model.A variety of parameters such as drift,floor acceleration and seismic damage are compared with cost and plausibility of the chosen options.The final outcome,the exte rnal bracing scheme used in this study does in fact decrease both the floor accelerations and the inter-story drift by at least 10% and in some cases as much as 85%.Consequently,a combination of innovative seismic retrofitting methods appeared to be more effective,achieving a more re sistant building under seismic hazards,by improving the stability and ductility of the structure.This gives rise to further researches and investigations for future solutions regarding seismic retrofitting applications and methodologies.