Seismic and progressive collapse assessment of new proposed steel connection

Abstract

The disastrous consequences of the partial collapse of the Ronan Point apartment in 1968 and Northridge earthquake in 1994, exposed the vulnerability of steel moment frames subjected to extreme loading. The reports of these two catastrophic events revealed the significant role of beam to column connection where the damage was mainly formed in this area. In this research, the performance of three different steel beam to column connections known as SidePlate, reduced beam section (RBS) and a new proposed “saddlebag” connection subjected to cyclic and progressive collapse experimentally and numerically were investigated. The main objective of this research was to evaluate the adequacy of the new proposed connection to resist extreme loading compared to SidePlate and RBS. Seismic performance evaluation was focused on the interstory drift angles based on 2010 AISC seismic provisions. In the other hand, investigation of progressive collapse was associated with satisfaction of acceptance criteria by rotational capacities of the connections provided in UFC 4-023-03 guideline. The results indicated that the new proposed connection was capable of achieving adequate rotational capacity of 0.2 radians, two times bigger than acceptance criteria, and developing full inelastic capacity of the connecting beams during the progressive collapse analysis. In addition, an excellent cyclic performance was demonstrated by the proposed connection as plastic hinges only appeared in the connected beams at the interstory drift angle of 0.06 radians, 1.5 times bigger than acceptance criteria. The seismic assessment also revealed that the proposed saddlebag connection possess adequate energy dissipation capacity attained by stable hysteretic behaviour into the inelastic range. The study also concluded that SidePlate provide adequate performance as it develop 0.2 radians of plastic hinge rotation angle and 0.06 radians of interstory drift angle to resist progressive collapse and cyclic loading respectively. However, RBS connection showed vulnerable performance to resist seismic and progressive collapse loading where tensile stress mainly appear at the groove welding.