Evaluation of Direct Displacement-based Designed Linked Column Steel Frame (LCF) Systems

The linked column steel frame (LCF) system is a new load resistant system; that by using replaceable ductile links, it can provide the desired structural behavior. The optimal performance of this system can be achieved by controlling the displacements and the sequence of yielding fuses in the structure. The direct displacement-based design (DDBD) method is one of the most powerful performance-based design methods that can control the behavior of a structure. This study aims to investigate the performance of LCF systems designed by the DDBD method. For this purpose, 8 sample structures with 3, 6, 9, and 12 stories and with different configurations, were designed with the DDBD method; and then their behavior was investigated by nonlinear static analysis. The results showed that in the design base shear calculated with the DDBD method, nearly most of the links of the studied structures were yielded; while all the beams of the modified moment frame remained elastic. This result shows the ability of the DDBD method to design LCF systems with controlled behavior. The results of the overstrength review of the studied structures also indicated that the overstrength of LCF systems designed with the DDBD method depends on the height and configuration. The average value of this coefficient was evaluated as 1.23. Also, the average inherent overstrength coefficient of the structural samples was calculated as 0.48. This result indicates the ability of the LCF systems designed by the DDBD method to achieve their desired failure mechanism.