Development of structural shear fuse in moment resisting frames

Abstract

Codes require that the span-to-depth ratio of the beams in moment resisting frames (MRF) should be limited to guarantee the development of plastic hinges with a sufficient length at beam ends. This requirement limits the application of MRFs mostly in framed-tube structures. In the current design procedure of steel MRFs, the strength and stiffness design of the structure are coupled often leading to overdesigned structures and foundations. To overcome the abovementioned limits, in this paper a new replaceable shear structural fuse is introduced for MRFs. The fuse is a shear link designed as a sacrificial component by weakening the shear strength of a segment at the middle of the beam to dissipate the seismic energy by shear yielding with stable hysteretic behavior. The monotonic and cyclic behavior of a single span-single story MRF with various beam span-to-depth ratios equipped with the proposed shear fuse is investigated through finite element modeling, verified using experimental data. The performance of the proposed system is compared with the conventional MRFs with flexural plastic hinges at reduced beam sections. In general, the shear yielding of the link is shown to be a great replacement for flexural hinges in MRFs, especially with low beam span-to-depth ratios.