Seismic Analytical Model for Retrofitted Old Reinforced Concrete Structures

Abstract

Abstract In seismic areas, a majority of such old buildings have only been designed for gravity loads or according to outdated seismic codes. Before1970's, smooth rebars were also extensively used in RC structures. As some of these buildings are still functioning, they need to be reassessed against seismic demands. Load bearing behaviour of concrete structures reinforced with smooth rebars is considerably affected by the slip deformation of the plain rebars. In this study a specific finite element model has been proposed for evaluating the seismic performance of these structures. The slipping characteristics of the smooth rebar have been incorporated in this model. To this aim, a tailored stress-strain property has been assigned to the steel fibers in tension. The model has then been calibrated/verified against several sets of experimental results, from other. In general satisfactory correlations have been noticed between the experimental results and the predictions from the proposed fiber element model. The model has also been used for a full seismic assessment of an existing RC building, having smooth rebars. In addition, the structure has been retrofitted with steel bracing, viscose dampers and base isolators schemes and their nonlinear seismic performance have been evaluated using the proposed model.