Experimental Evaluation of Replaceable Shear Fuse Moment Connections

Shannon Shun Oh, Brigham Young University


Steel special moment frames (SMFs) are known to be highly ductile seismic force- resisting systems. The performance of an SMF relies on the ability of the connections to accommodate large inelastic deformations. After the brittle failure of some steel moment frame connections during the 1994 Northridge Earthquake, experimental tests were used to investigate the ductility and strength of these connections. An experimental study was performed to investigate the seismic performance a new connection called the Replaceable Shear Fuse (RSF) connection. The RSF connection uses shear-yielding fuse plates to prevent beam and column yielding. A total of 7 test specimens with varying fuse plate sizes and configurations, a W14×48 column, and a W14×38 beam were created. The connections were loaded laterally and cyclically at increasing displacements until the connection failed. The results show that RSF connections have the capability to prevent beam and column damage by focusing inelastic rotations to shear fuse yielding and bolt slip. Specimens with 14 in. deep beams achieved rotations ranging from 0.06 to 0.10 rad without excessive degradation and local buckling. Stable yielding was also achieved for all test specimens. Hysteretic responses for Specimens A1.3 and A1.4 were similar to typical responses from welded moment connections. The behavior of Specimen A1.16 was similar to that of a bolted flange plate connection, whereas the other remaining specimens had responses that were a combination of welded moment and bolted flange plate connections. Peak responses from tests indicated that inelastic rotations were accommodated by both fuse plate yielding and bolt slip. The first observation of major bolt slip occurred in the fuse plates as early as the 0.05 rad drift cycle. The early occurrence of bolt slip allowed for a higher rotational capacity. While the top and bottom fuse plates were replaced for each test, no repairs were needed for the beam and column. The RSF connection proved to be a more resilient alternative SMF connection.