Experimental and numerical investigation on the seismic retrofit of RC frames with linked column frame systems

Abstract

The Linked Column Frame (LCF) system consists of the main lateral load bearing system of the structure called the Linked Column (LC) frame; the structural system is Moment Resisting (MF) frame acts as gravity load bearing system. This system can use to retrofit the reinforced concrete (RC) or steel frame. This paper presents the results of an experimental and numerical investigation of the RC frame retrofitted with the LCF system which the sections of the LC frame are designed using proposed simplified equations. The design of the LC frame is based on the proposed equations in a way that the plastic hinges are first formed in the link beam and then in the columns of the LC frame. The results indicated that the tested specimen and numerical models that the RC frames retrofitted with the LCF system using the proposed equations had good stiffness, high ductility, and significant energy dissipation. The results showed that the ductility factor, the average elastic stiffness and the system bearing capacity of the RC frames retrofitted with the LCF system using the proposed equations are increased about 1.5, 7.6 and 3.7 times, respectively. Also, using the proposed equations for the design of the sections of LC frame, the formation progress of plastic hinges is formed at the Rapid Repair (RR) performance level. In addition, the ratio of the first plastic hinge formation in the beam of RC frame (Δp LCF) to the first plastic hinge formation in the beam of LC frame (Δy LCF) for the RC frames retrofitted is close to 3. In other words, the RC frames retrofitted with the LCF system based on the proposed equations are more capable of withstanding earthquake forces without damaging the members of the main frame (RC frame).