Seismic Performance of Steel MRFs with Partially-Restrained, Bolted, Beam-to-Column Connections through FE Simulations

Even though partially-restrained, bolted, beam-to-column connection systems are not explicitly certified to be used for moment resistance in current building specification jurisdictions, they represent a promising solution in modern steel moment-resisting frames (MRFs), showing their significant potential to be able to mitigate some of the major drawbacks inherently related to the geometry of welded connections. In order to quantify the influence of this attractive solution, applicable both to new construction and to the retrofitting of existing structures - on the global response of whole MRF buildings under seismic loads - a numerical procedure, based both on refined three-dimensional solid and one-dimensional fiber-based finite element (FE) models, has been developed and validated using past experimental results. This validated numerical approach has been used to assess the seismic performance of T-stub connection systems within entire MRFs, in comparison with the response of other top-and-seat angle joints. A series of conventional and adaptive pushover and incremental dynamic analyses, accounting for material and geometric nonlinearities, has been carried out to quantify behavioral changes as a consequence of geometric variations in the connection system.