Determination of Response Modification Factor of the RC frame retrofitted with the linked column frame system

The adequate solution for protecting main structural members and reducing the destructive effects of earthquakes use of structural systems combined with the replaceable fuse members, which due to the ductile behavior and seismic energy dissipation are next to the main members of the structure. Relatively low cost and easy repair process in these systems leads to rapid return to occupancy after an earthquake. In this study presents the response modification factor ‘R’ of the RC frame retrofitted with the linked column frame system with the number of floors 3- and 6-story with three different lengths of link beam. Based on the results of modeling the force-displacement curve, the R factor and related parameters are calculated based on the equivalent energy method. The results of the nonlinear static analysis, using the linked column frame system for retrofitting RC frame Can be increased the load bearing capacity and the capability of absorption and dissipation energy than a model of the RC frame without retrofitting about 3.5 times. The R factor in the Limit state method is about 8.95 which is more about 71% than a model of the RC frame without retrofitting. Also, the distance the corresponding displacement for the first plastic hinges formed in link beam and the corresponding displacement for the first plastic hinge formed in the RC frame for the model of LCF-0.8-0.45 is more than other models. This causes the damage to the replaceable link beam and the main structure is remained elastic phase and at a high risk level, this system will achieve to reach the rapid return to occupancy performance level.