Seismic resilient steel moment connections with top shear tabs and bottom replaceable metallic fuse: Analytical and experimental study

Abstract

A new seismic resilient steel moment connection with top shear tabs and bottom replaceable metallic fuse is proposed. The shear tabs are realized by a combination of shear angles, with or without shear plates or splice plates, while a buckling-restrained plate (BRP) is employed as the fuse. Both the shear tabs and BRP are placed at a splice location which represents the beam inflection point under gravity load. Analytical models were developed to determine the stiffness, strength, and deformation of the proposed connection, as well as a trilinear moment-rotation relationship at the spliced section. In this way, a coordinated seismic design procedure to achieve structural serviceability and resilience in steel moment frames with the proposed connection was derived based on the equal-stiffness and zero-moment strategies. Cyclic loading tests of full-scale beam-to-column subassemblies equipped with the proposed connection were conducted. Three resilient connections with different shear tabs (bolted/welded shear angles above/below the beam top flanges) were examined and compared with a conventional fully welded connection. The test results validated the concept and confirmed success of the analytical and design methods to ensure sufficient lateral stiffness and concentrate plastic damage into the BRP. Moreover, the resilient connections with bolted or welded shear angles above the beam top flanges exhibited about 11–18% higher moment resistance at 4% drift and 20% more energy dissipation, and thus are recommended over that with welded shear angles beneath the beam top flanges.