Performance of pre-1970s squat reinforced concrete shear walls

Abstract

The seismic performance of pre-1970s squat reinforced concrete shear walls is assessed with the capacity spectrum method to expose structural deficiencies that arise due to current estimates of seismic demands. The walls are 1/3 scale models of a prototype building, designed and detailed in accordance with the 1965 edition of the National Building Code of Canada (NBCC-1965) for four locations, two in high seismic zones in western Canada and two in moderate seismic zones in eastern Canada. Seismic demands for different drifts are evaluated against the spectral capacities of the walls to determine the performance. The seismic demands are based on uniform hazard spectra specified by the NBCC-2015. The calculated effective damping and the spectral capacity of the walls are determined from the force–displacement envelopes of the reverse cyclic responses of the shear walls. In addition, spectral capacities based on experimental and numerical results are used to study the effect of axial load and low-strength reinforcing steel on the performance of the shear walls.