Investigation of the Effects of Link Beam Length on the RC Frame Retrofitted with the Linked Column Frame System

This study investigates the effect of different link beam lengths in the Reinforced Concrete (RC) frame retrofitted with the Linked Column Frame (LCF) system. It also investigates the ratio of the link beam length (e) to the span length of the RC frame (L) from 0 to 1.5 for the 9 models of the RC frame retrofitted by the LCF system has been investigated. In addition, it studies the formation of plastic hinges in the RC and Linked Column (LC) frame, distribution of stiffness between the RC and LC frame and the ratio of the structural displacement with the formation of the first plastic hinge in the member of the RC frame at the collapse prevention level (∆p LCF) to the structural displacement with the formation of the first plastic hinge in the link beam (∆y LCF) has been studied. Based on the nonlinear static analysis results, the model with the ratio of e/L= 0.45 has a better performance than other different lengths of the link beam. In this model, the stiffness of the LC frame has increased about 78% in comparison with the model with the ratio of e/L that is more than 0.6. Also, the ratio of ∆p LCF to ∆y LCF for the model of e/L = 0.45 in comparison with two models of e/L = 0.3 and 0.6 is more about 14% and 22%, respectively. It means that, the model of e/L = 0.45 has more potential to reach the performance level of Rapid Repair (RR) to occupancy.