SEISMIC SHEAR-STRENGTH OF REINFORCED-CONCRETE COLUMNS

Aspects relating to the shear strength of circular and rectangular col umns under seismic loading are presented. An examination of existing d esign equations reveals wide differences in predicted responses. Parti cular emphasis is placed on models capable of representing the interac tion between flexural ductility and shear strength. A simple method is proposed whereby the strength enhancement provided by axial compressi on is separated from the concrete component of shear strength and cons idered to result from arch action. The strength of the concrete compon ent is reduced as flexural displacement ductility increases. Predictio n of shear strength from the proposed and alternative methods are comp ared with results from a wide range of tests of columns failing in she ar. The proposed method is shown to provide significantly improved cor relation with experimental results. Conservative modifications are mad e to enable the method to be used for design.