GNGTS 2021 - Atti del 39° Convegno Nazionale

GNGTS 2021 S essione 2.2 262 PERFORMANCE-BASED ASSESSMENT OF SEISMIC-RESILIENT STEEL MOMENT RESISTING FRAMES EQUIPPED WITH INNOVATIVE COLUMN BASE CONNECTIONS E. Elettore 1,* , A Lettieri 1 , F Freddi 2 , M Latour 1 , G Rizzano 1 1 Department of Civil Engineering, University of Salerno 2 Department of Civil, Environmental and Geomatic Engineering, University College London Many recent research studies have focused on developing innovative seismic-resilient structural systems by chasing the objectives of minimising both repair costs and downtime in the aftermath of an earthquake. In this regard, recent research works have investigated an innovative type of self-centring damage-free column base connection, demonstrating its beneficial effects when used within steel moment-resisting frames (MRFs), both in terms of residual drifts reduction and of protection of the first storey columns from yielding [1-2]. The proposed connection [1] consists of a rocking column equipped with a combination of friction devices, providing energy dissipation capacity, and post-tensioned steel bars with disk springs, introducing restoring forces in the joint. It has dimensions comparable to the size of a traditional column splice and it is located above a traditional full-strength base plate joint, as illustrated in Fig 1 (a). The friction devices are composed of friction pads coated with thermally sprayed metal, pre-stressed with high strength bolts, placed between the steel cover plates and the column, as described in Fig 1 (b). The disk springs, arranged in parallel and series, act as amacro-spring system, ensuring sufficient deformability to the connection and an adaptable stiffness-resistance combination. Fig 1 (b) shows the details of the oversized and slotted holes of the column’s web and flanges, which are designed to accommodate the gap opening required to reach the target rotation. The moment–rotation behaviour can be described by simple analytical equations, allowing the definition of an easy-to-apply design procedure. Fig 1 shows the details of the oversized and slotted holes of the column’s web and flanges, which are designed to accommodate the gap opening required to reach the target rotation. Fig. 1 - Self-centring column base connection: (a) 3D view; (b) 3D exploded view.