Innovative Seismic Performance Enhancement Techniques for Steel Building Moment Resisting Connections

Seismic performance enhancement techniques for steel building moment connections intended for use in special moment frames are studied experimentally and through rigorous simulation modeling. The first performance enhancement technique involves reducing the strength of steel over specified regions of the beam flanges by exposing the regions to high temperatures followed by slow cooling. This technique promotes development of the beam plastic hinge away from the welded joint. The second technique involves relocation of the bolts of an 8-bolt extended end plate connection to distribute bolt forces uniformly, and thereby avoid bolt and end plate failures. The third technique involves a new shear tab design and bolt arrangement of welded unreinforced flange bolted-web (WUF-B) connections to more effectively transfer stress from the beam web to the column flange. Finally, the fourth performance enhancement technique involves stiffening the beam web within the plastic hinge region to delay the onset of local web and flange buckling resulting in the delay of strength degradation. Experimental validations of these seismic performance enhancement techniques are presented. Rigorous simulation models of the connections were developed based on an advanced non-linear kinematic hardening rule constitutive model in ANSYS Finite Element Software. The simulation results were instrumental in developing the novel ideas for enhancing seismic performance of steel building moment connections.