EFFECT OF CONFINEMENT ON DUCTILITY' OF RC HOLLOW CIRCULAR COLUMNS

Abstract

Generally the hollow concrete members are used in locations where the cost. of }~-~°qL concrete is relatively high or in situations where the weight of concrete is to kept IJ minimum. In the case of columns, i.e., the hollow circular columns are used as bridge piers, staging for elevated water tanks, power poles and sign posts. In earthquake prone areas, these members are subjected to large seismic or lateral forces and expected to undergo large inelastic deformations. To sustain these inelastic deformations the member should have good ductility, i.e., the ability to dissipate energy with out degradation of strength. The wid usage of these hollow circular columns forced to study their available curvature ductility and flexural strength. D is It h s well established that well confined concrete members can sustain large inelastic strains without significant loss of strength. 4 e-s se &f follow circular column members having sufficient thickness to pfe-vide two layers of longitudinal and transverse reinforcement on thecThlnside and outside faces of the cross-section, behave/ in~uctile manner and sustain large inelastic strains due to proper confinement of core concrete. However in the case of hollow circular sections with small cross-sectional size, it may not be convenient to provide two layer of steel. In such situations only one layer of steel is providednear the outside face of the column cross section. Though it isjsimple arrangement , it behaves in,\brittle manner.