Collapse Performance of Nominally Identical Nonductile Circular Columns Susceptible to Failure-Mode Variability

Abstract

Recent analytical studies have highlighted the existence of a failure-mode transition zone within which nominally identical test specimens may experience variability in failure mode between a flexure-dominated and a shear-dominated mechanism. This paper presents a study on the seismic response of four nominally identical nonductile RC circular columns susceptible to failure-mode uncertainty designed to represent typical New Zealand pre-1995 poorly detailed gravity columns. In this study, the influence of inherent material uncertainty and displacement history on the collapse response of the nominally identical columns was investigated. Experimental results showed that the failure mode of lightly confined RC columns can be influenced by displacement history and inherent material uncertainty. As observed in this study, the nominally identical columns experienced different failure modes, even under the same loading protocol, leading to a significant variation in drift capacity at axial failure (ranging from 1.5% to 2.6%) and residual axial capacity of RC columns (ranging from 200 to 650 kN).