Effect of rounded corners on ultimate strength of FRP confined concrete columns

Abstract

Fiber Reinforced Polymer (FRP) confinement improves the strength and ductility of axially loaded columns. The improvement depends on several parameters. Cross sectional shape is an important parameter which decides the confinement effectiveness of FRP wrap. Commonly the column cross sections are circular or rectangular. Circular cross sections are uniformly confined and perform better than the equivalent cross sectional area of rectangular and square cross sections, whereas in rectangular and square sections the confined stress is non-uniform, which leads to failure of FRP earlier than the failure occurs in flat coupon tensile test. In this study an attempt has been to study the effect of corner radius on ultimate strength of rectangular and square cross section columns which has been confined by Glass Fiber Reinforced Polymer (GFRP) wrap. As a trial, the first stage of experimental work was performed on twenty one square concrete stubs of size 125mm × 125mm ×300mm. Six corner radius 0mm (sharp corner), 8mm, 13mm, 18mm, 25mm and 50 mm were selected to study the effect of corner radius newline