Fuse performance in steel frames with knee element connections under cyclic loading

This paper describes the development of a ductile fuse system to reduce Seismic demand in steel frames with knee element connections. In these types of structures, connections often require reinforcement to withstand the tensile capacity of the brace to comply with the capacity design process.To overcome this problem, it is necessary to think of a solution to prevent the premature failure of the connection.For this purpose, in this research, different models of ductile fuses consisting of a reduced cross-sectional area are placed on the brace of the knee element in a braced frame.The fuses are designed to reduce the tensile capacity of the knee element braces to the capacity of the joints. The results show that the braced frame with fuse can be used to reduce the seismic load demand to the connections sufficiently, to prevent the strengthening of the connection caused by the application of capacity design principles. It was also observed that the properly designed fuse system in braced frames shows a stable hysteretic response under cyclic loading and maintains sufficient ductility with a reasonable reduction in the compressive strength of the braced members. Also, the results showed that the failure of all samples occurs in the fuse, and as a result, by using the fuse, it is possible to use the full capacity of the connection and brace. Finally, based on the results of the study, the best fuse models that creates both Sufficient ductility and compressive strength to an acceptable level were identified for design applications.