Seismic Performance of Concentrically Braced Frame With Friction Sliding Connections: Learning From Subassembly Component Tests, Numerical Simulations and Shake Table Tests

Abstract

Concentrically braced frames (CBFs) are one of the common systems to provide load resistance for structures under lateral loads. However, when loaded beyond the elastic range, the brace itself is prone to buckling under compressive axial force and will result in unequal forces in the braces under tension and compression. This is incorporated into current design procedures, but results in reduced performance in severe earthquakes. Several low damage design concepts have been developed and implemented in the recent years to overcome this brace buckling issue. One of these is the use of friction-sliding connections (FSCs) as the dissipative component. CBFs with friction sliding dissipative mechanisms can exhibit inelastic deformation capacity through friction sliding in both tension and compression along the line of the brace, with forces limited to avoid section or member buckling and non-ductile fracture of braces. In a research programme to determine the brace and system behaviour, quasi-static testing on a subassembly of brace-to-gusset plate connection with FSCs was first undertaken to verify its adequate deformation and resistance. The obtained hysteretic characteristics were then adopted in SAP 2000 for numerical simulation of a three-storey CBF. Finally, shake table testing of the three-storey CBF was conducted, including V-bracing and diagonal bracing configurations. This paper reports the key findings from the preliminary design, numerical simulation, and experimental testing and provides guidance on how to design these systems using current CBF design procedures with appropriate modifications.