An Investigation on Global Ductility of Strengthened RC Frames

This paper presents a comparative study of global ductility of a reinforced concrete (RC) frame strengthened with external structural walls. The effect and suitability of the approaches used for evaluation of global yield displacement were examined. Then, using experimental and analytical methods, the variation of global ductility was investigated. In the experimental study, 1/3-scaled two plane frame systems, one unstrengthened and the other strengthened with external structural walls, were tested under lateral cyclic loads. In the analytical study, the pushover analyses of these two plane frames were performed with IDARC-2D and SAP2000. The variation in the global ductility ratio was analysed in terms of the global yielding displacement related to the system ductility by applying different approaches to the capacity curves drawn from the experimental data and analytical methods. The results showed that it was important to select a suitable approach to the evaluation of the global yield displacement, which has a vital influence on global ductility. The global ductility ratios obtained from first significant member yield (FSMY) approach and Paulay's approach are closer to the experimental results.