Reinforced concrete (RC) non-seismic frames in Middle Eastern multistory buildings often have beam–column connections with discontinuous bottom reinforcement, heightening the risk of progressive collapse if an outer column fails. This study aimed to reduce the potential for progressive collapse when a column is lost by investigating the use of bolted steel plates to enhance the beam–column joints of such frames. In this regard, high-fidelity finite element (FE) analysis was carried out on ten half-scale, two-span, two-story RC frames to simulate the removal of a center column. The numerical analysis accounted for the nonlinear rate-dependent response of steel and concrete, as well as the bond-slip model at steel bars/concrete interaction. The analysis matrix had three unstrengthened specimens that served as references for comparison, in addition to seven assemblies, which were strengthened using bolted steel plates. In the upgraded assemblies, the studied variables were the grade of steel plate (three grades were examined) and the upgrading scheme (three different schemes were investigated). The performance of the specimens was evaluated by comparing their failure patterns and the characteristics of load versus displacement of the middle column during both flexural and catenary action phases. Based on this comparison, the most efficient strengthening method was suggested.
Elsanadedy et al. (Sun,) studied this question.