ASSESSMENT ON FAILURE MODE OF REINFORCED CONCRETE COLUMNS

Abstract

Strength ratio, as defined as shear strength divided by flexural strength, is widely used to assess a failure mode of RC columns. However, several studies have revealed that even columns with the ratio much more than unity occasionally fail in shear during earthquakes, if shear strength is computed based on Truss and Arch Mechanism (TAM). This study is intended to throw light on the above issue. Past tests by the authors show specimens representing old columns with a few amount of hoop tend to fail in shear just when a shear crack occur, or before TAM forms. It is pointed out from discussions on the test results that shear strength should be defined as a value which is larger among the TAM strength and shear crack strength to assess a failure mode of old columns more accurately.