What controls the failure process of irregularly-shaped reinforced concrete columns

Abstract

This paper presents the results of an experimental study of six irregularly-shaped reinforced concrete columns. The column specimens were subjected to a cyclic loading varying in time and to a constant concentrically applied axial load. Steel reinforcement and concrete strains together with maximum lateral deflection were recorded as the lateral load was varying during the experimental test. Envelopes of hysteretic load-deflection curves are plotted. Through load-deflection curves, the failure process of the tested columns is described. The experimental results demonstrate that the concrete column's failure is a process and not a fixed point. The failure process starts with the cracking of the tensile concrete at the critical cross-section. It is found that the maximum load point is the peak of the failure process while the maximum bending moment occurs later. The first point represents the stability failure, while the second corresponds to the material failure of the columns. The test results show that the columns' failure is caused by instability rather than the loss of strength.


(Journal of Civil Engineering, JKUAT: 2002 7: 45-54)