Seismic Shear Strength of Reinforced Concrete Columns

TLDR

Shear strength of circular and rectangular reinforced concrete columns under seismic loading is examined, revealing wide discrepancies among existing design equations. The study aims to develop a simple method that separates axial compression‑enhanced shear strength from the concrete component, focusing on flexural ductility–shear strength interaction. The proposed method models shear strength by separating axial compression effects from the concrete component, reducing the latter with increasing flexural ductility, and is calibrated against extensive shear‑failure tests with conservative design modifications. The method demonstrates significantly improved correlation with experimental shear‑failure data compared to existing approaches.

Abstract

Aspects relating to the shear strength of circular and rectangular columns under seismic loading are presented. An examination of existing design equations reveals wide differences in predicted responses. Particular emphasis is placed on models capable of representing the interaction between flexural ductility and shear strength. A simple method is proposed whereby the strength enhancement provided by axial compression is separated from the concrete component of shear strength and considered to result from arch action. The strength of the concrete component is reduced as flexural displacement ductility increases. Prediction of shear strength from the proposed and alternative methods are compared with results from a wide range of tests of columns failing in shear. The proposed method is shown to provide significantly improved correlation with experimental results. Conservative modifications are made to enable the method to be used for design.