Experimental Investigation of External Confinement of Reinforced Concrete Columns by Hollow Structural Section Collars

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Title: Experimental Investigation of External Confinement of Reinforced Concrete Columns by Hollow Structural Section Collars

Author(s): Munawar A. Hussain and Robert G. Driver

Publication: Structural Journal

Volume: 102

Issue: 2

Appears on pages(s): 242-251

Keywords: collars; columns; ductility; earthquake-resistant structures; external confinement; rehabilitation; reinforced concrete; strength

Date: 3/1/2005

Abstract:
Methods are available for strengthening circular reinforced concrete columns that confine the concrete using primarily membrane action. Since these methods are not as effective for square and rectangular columns, a relatively simple noninvasive scheme is proposed that confines the concrete with a combination of significant flexural and axial stiffness. An experimental investigation of the behavior of square concrete columns strengthened by steel hollow structural section (HSS) collars has been carried out. This initial phase of the research considered only axial loading and consisted of a total of 11 full-scale column tests. Two control columns with conventional internal tie reinforcement and nine columns with external confinement by HSS collars were tested. The effects of collar stiffness, spacing, type of corner connection (bolted or welded), and active confining pressure on the confined material curve have been studied. The results indicate that the provision of HSS collars results in considerable enhancement in strength as well as ductility.