Lateral Stability Limits for RC Wall Boundary Zones Based on Axial Response of Idealized Prisms

Abstract

ABSTRACT Seismic performance of flexurally-dominated reinforced concrete (RC) walls largely depends on the ability of its confined end regions to withstand axial stress reversals. Observed compression failure modes in these end boundary regions during the Chile (2010) and New Zealand (2010–11) earthquakes led to extensive experimental research that involved testing isolated rectangular columns (or prisms) representative of wall boundary zones under axial cyclic loading. This study scrutinizes the effect of slenderness (height-to-thickness) ratio on the compression failure modes of such wall boundary zones. For this purpose, uniaxial cyclic tests were conducted on four doubly RC prisms representative of rectangular wall boundary zones designed in accordance with ductile detailing requirements of New Zealand Concrete Standard. The test results are presented in detail and the effect of slenderness on progression of two different types of instability, namely local and global, is elaborated. The experimental measurements are compared with the analytical predictions of three phenomenological models proposed in the literature to prevent development of out-of-plane instability in structural walls. Relationships between the effective boundary element slenderness and different compression failure modes are established using the results of this study as well as previous experimental investigations conducted by other researchers. Finally, this paper attempts to provide limitations on the ratio between unsupported wall height to wall thickness deduced from the effective boundary element slenderness limits so that protection against lateral instability in ductile structural walls could be ensured.