Retrofitting of Existing Building by Concrete Jacketing

Abstract

Seismic Retrofitting is engineered mitigation techniques for structural engineers. It is defined as the modification of existing structures to make them more resistant to seismic activity, ground motion or soil failures due to earthquakes. It is generally required for earthquake damaged and vulnerable buildings with no exposure to severe earthquakes. Retrofit enhances the structural capabilities of the building. In present time, there are many local and global retrofit techniques in practice across the globe, out of which only concrete jacketing will be taken up for study in the thesis work. Performance of the retrofitted building will be evaluated for target performance objectives under considered hazard level. Performance based design will be carried out to substantiate the retrofit sizes. The primary target of this document is to provide a technically sound, acceptable guidelines and modelling procedures for seismic retrofitting of building structures. Linear and nonlinear analysis will be performed to evaluate the capacity as well as damage of the structure. RCC frame buildings of different heights namely, 5, 6, 7 and 8 storeys have been considered. A single regular plan has been considered. The input sizes of beams and columns are same as that of the existing frame structures taken up for retrofit scheme.

For analysis and design check of buildings, ETABS v15 has been used. Beams and Columns have been modelled as frame elements. Beam and column sizes have been taken as per the existing values. Retrofitted sections will be suggested and modelled on a utility called Section Designer in ETABS based on Column-Beam Capacity Ratio. Nonlinear default hinges have been applied to beams and columns as per ASCE 41 document (FEMA 356). For nonlinear time history analysis, spectrum compatible ground motions have been used. The final conclusion will be suggesting the buildings performance levels corresponding to a certain retrofit scheme.