SEISMIC CAPACITY OF RC HOLLOW BLOCK SLAB BUILDING AND RETROFITTING SYSTEMS

Abstract

Retrofitting the seismically deficient structures before earthquakes provides a feasible approach toimprove their load carrying capacity and reducing their vulnerability. This study presents ananalytical assessment investigation on hollow block slab reinforced concrete building. The buildingis not designed according to seismic standards; moreover, hollow block slab systems may lack thesufficient lateral seismic resistance. Different retrofitting systems to enhance the seismic capacity ofthe target building are proposed and evaluated. These systems include strengthening the columnswith reinforced concrete jackets or using internal shear walls or introducing steel chevron bracing.The target building before and after retrofitting is analyzed either as bare frames or consideringmasonry infill walls with different parameters. The three dimensional nonlinear pushover analysisprocedures are used in evaluating the seismic performance of the original building and the retrofittedones. The demand response spectra proposed by the Egyptian Code of Loads, ECOL 201, 2012edition, for different seismic zones with different soil properties are utilized in the evaluation. Realseven earthquakes response spectra with maximum-scaled spectrum acceleration close to the onecalculated for Cairo city are also applied. It is found that the original target building, beforeretrofitting, fails to fulfill the demands of neither many of the ECOL response spectra nor many ofthe applied real earthquakes. All the proposed retrofitting systems succeed in highly enhancing theseismic capacity of the original building. Considering masonry infill walls in the analysis has acrucial role on the seismic performance of the original building, the retrofitting systems can, due tothe increase in the lateral strength, limit this effect.