Nonlinear behaviour of FRP-retrofitted RC coupled shear walls

This paper presents a numerical study of the effectiveness of fibre-reinforced polymer (FRP) composites in upgrading the seismic performance of conventional reinforced concrete (RC) coupled shear walls. The study investigates the performance of two RC coupled shear wall buildings with different heights when their coupling beams are retrofitted using FRP U-wraps for increased ductility of the beams. The 10- and 15-storey existing buildings are located in Montreal, Canada, and were designed according to the 1970 National Building Code of Canada (NBCC). The FRP retrofit aims to increase the shear capacity of nominally ductile coupling beams, and hence increase their rotational ductility to the limited ductility, moderate ductility, and ductile levels. Nonlinear incremental dynamic analyses were conducted for existing and FRP-retrofitted buildings when subjected to twelve ground motion records with different frequency contents. The seismic behaviour of the analyzed cases was compared based on the maximum earthquake intensity that can be resisted by the building, maximum interstorey drift ratio, maximum storey shear, maximum coupling moment, maximum energy dissipated, and maximum wall forces. Moreover, the twelve earthquake records were scaled to match the NBCC 2015 design response spectrum of Montreal to determine the optimum retrofit level for the coupling beams of the two buildings in consideration.