SEISMIC SHEAR-STRENGTH OF REINFORCED-CONCRETE COLUMNS

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.