Evaluation of models of the flexural response of rectangular reinforced concrete columns in the post-capping region

Abstract

Simulating the seismic behaviour of a structure up to the point of collapse is an established approach to assessing structural safety during strong earthquakes. In the case of reinforced concrete columns with a predominantly flexural response, a lumped plasticity model with a predefined backbone and Takeda hysteresis rules is often used for this purpose. The present study investigates different moment-rotation backbone models to identify procedures that adequately predict the post-capping part of the backbone. In the first part of the paper, Eurocode 8 procedures for estimating the rotation in the near collapse limit state are reviewed and used to calculate the near collapse rotation of two experimentally tested columns with different levels of confinement. The procedure that agrees best with the experiments is used in the second part of the study, where several options for modelling the post-capping part of the moment-rotation backbone are studied. The results suggest that a quadrilinear moment-rotation backbone with a bilinear post-capping region combined with anearcollapse rotation determined according to the empirical procedure from the current version of Eurocode 8/3 can predict the cyclic response of both poorly and well-confined columns.