Seismic Strengthening of Deficient RC Buildings Using Externally Bonded FRPs R. Garcia, I. Hajirasouliha, K. Pilakoutas, and M. Guadagnini Dept. of Civil and Structural Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin St. S1 3JD, UK Th. Chaudat CEA, DEN, DM2S, SEMT, Laboratoire d’Etudes de Mécanique Sismique, 91191 Gif-sur-Yvette Cedex, France ABSTRACT: A full-scale RC building with poor detailing in the beam-column joints was tested on a shake table. After initial tests which damaged the structure, the frame was strengthened using FRPs and re-tested. This paper studies analytically the efficiency of the strengthening at improving the seismic performance of this frame. The experimental data from the initial shake table tests are used to calibrate analytical models. To simulate deficient beam-column joints, steel-concrete bond-slip and bond-strength degradation models are considered. The analytical models are used to assess the efficiency of the FRP rehabilitation using real seismic records. The FRP intervention enhanced the behaviour of the substandard joints, and resulted in substantial improvement of the seismic performance of the damaged RC frame. It is shown that after strengthening, the damaged building would experience on average 65% less global damage compared to the original structure if it was subjected to a set of real seismic records. Keywords: dynamic analyses, seismic strengthening, FRPs, RC frames 1. INTRODUCTION Much of the existing building stock in Europe and in many developing countries was designed using pre-seismic construction practices and often suffers from poor quality materials. Consequently, these buildings have deficient lateral load resistance and insufficient energy dissipation that can rapidly lead to collapse during strong earthquakes. Strengthening these seismically deficient structures provides a feasible and cost-effective approach to improving their load carrying capacity and reducing their vulnerability. Among the different techniques currently available for seismic strengthening, Fibre-reinforced Polymers (FRPs) have demonstrated to offer effective and attractive solutions. Several experimental tests have been conducted to investigate the behaviour of deficient full-scale RC buildings strengthened with FRPs using PsD (Pinto et al., 2002; Balsamo et al., 2005a; Balsamo et al., 2005b; Di Ludovico et al., 2008a; Di Ludovico et al., 2008b) or quasi-static lateral load tests (Della Corte et al., 2006). Based on the results of these tests, analytical models were developed to study the seismic behaviour of deficient and strengthened RC buildings (Jeong & Elnashai, 2004; Kosmopoulos & Fardis, 2007; Galicia et al., 2007). However, the efficiency of FRPs at improving the seismic behaviour of deficient full-scale RC frames using shaking table tests has not been investigated. This paper investigates analytically the efficiency of Carbon FRPs (CFRPs) at improving the global performance of substandard RC buildings under real seismic excitations. This is achieved by using data from shaking table tests on a full-scale RC frame with poor detailing in the beam-column joints. The tests were performed on the shake table of the CEA-Saclay Laboratory as part of the EU-funded Project ECOLEADER. The frame was designed and built according to typical pre-seismic construction practice of southern Europe. Initial shaking table tests were carried out until significant damage was observed. Subsequently, the damaged frame was repaired, and columns and beam-column joints were strengthened using externally bonded CFRPs to perform additional tests. The bare and rehabilitated