Influence of longitudinal reinforcement layouts on RC wall performance
Design recommendations for longitudinal reinforcement layouts of reinforced concrete (RC) walls have been derived from plane section analyses. Such an analysis generally favours wall layouts with boundary elements containing large amounts of vertical reinforcement, providing higher moment resistance and larger ductility capacity than the same reinforcement distributed evenly along the wall length. The main disadvantage of a design method based on a plane section analysis is that it disregards the beneficial influence that the distribution of longitudinal reinforcement has on the member shear performance and reduction of crack widths. In order to better understand the seismic performance of RC walls with concentrated and distributed longitudinal reinforcement layouts, this paper starts with a review of simple mechanical models and code prescriptions on stability of rectangular walls, sliding shear resistance, and required confinement reinforcement. The relevant expressions from this survey are then applied to a case study comprising two walls. In addition, the latter are numerically simulated with an advanced nonlinear membrane model to avoid the limitations of plane section hypothesis. Pushover analyses show that distributed reinforcement layouts can lead to an improved wall behaviour in terms of crack widths and spacing along the wall height, as well as a different failure mechanism due to crushing of the compressed zone instead of a premature sliding shear failure at the base of the wall.