Strain Localization in Confined High-Strength Concrete Columns

Abstract

The postpeak behavior of high-strength concrete (HSC) columns, loaded in axial compression, is characterized by strain localization in the concrete leading to the formation of an inclined shear failure plane separating the concrete into two wedges restrained by the cohesion of concrete and the reinforcement steel. A model capable of predicting this postpeak load-displacement behavior of confined HSC columns loaded in axial compression is presented. The proposed descending branch is consistent with the physical phenomena observed from axial compression tests on 62 confined HSC columns from three independent research projects. The proposed model shows that the pseudobrittle failure of HSC columns, loaded in compression, come from the fact that the residual axial capacity of the column after failure is mainly controlled by the lateral load carried by the transverse reinforcement and therefore by its yield strength.