Probabilistic Seismic Assessment of SMFs with Drilled Flange Connections Subjected to Near-Field Ground Motions

This paper aims to probabilistically evaluate the influences of drilled flange (DF) connection on seismic performance of steel moment frames (SMFs) incorporating near-field ground motions. Meanwhile, reduce beam section (RBS) connection as a prequalified connection and pre-Northridge welded unreinforced flange (WUF) connection were compared with DF connection. To model accurately the components of RBS and WUF connections and panel zone in SMFs, the proposed models of former researches were utilized. However, to simulate all DF connections the hinge properties were extracted from experimentally validated finite element models. Two sample low- and high-rise buildings were designed based on valid codes and simulated by OpenSees platform in order to study the nonlinear performance of aforementioned connections. Incremental dynamic analysis process was carried out to assess comprehensively the effect of DF connection on structural response and probability of structural instability for various intensity of seismic loads. Then, the seismic risk for Collapse Prevention and immediate occupancy limit states were calculated by fragility analysis. Also, seismic demand hazard curves for the sample buildings were extracted. The results of this study indicated that DF connections provided acceptable seismic performance as well as RBS connections in low- and high-rise buildings.