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Title: Confinement Model for Concrete Columns Reinforced with GFRP Spirals

Author(s): Priyank P. Sankholkar and Chris P. Pantelides

Publication: Symposium Paper

Volume: 327


Appears on pages(s): 8.1-8.18

Keywords: Axial load; Axial Strain; Compressive strength; Confinement model; Concrete column; Ductility; Fiber reinforced polymer; Glass fibers; Hoop Strain; Spiral

DOI: 10.14359/51713328

Date: 11/1/2018

Confinement of concrete using glass fiber reinforced polymer (GFRP) spirals was evaluated using small-scale concrete cylindrical specimens with a 254 mm (10 in.) diameter and 762 mm (30 in.) height under concentric axial compression. The contribution of longitudinal GFRP bars to confinement was excluded by using wood dowels as longitudinal reinforcement to maintain a constant spiral pitch. Thus, concrete confinement was provided exclusively by the GFRP spiral. An ultimate hoop strain of 1.0 to 1.5% was achieved for the GFRP spirals of well-confined small-scale concrete specimens. Expressions were developed for the confined compressive strength and ultimate axial compressive strain of concrete confined with GFRP spirals. The resulting confinement model is compared to axial column tests of reinforced concrete columns with GFRP spirals and GFRP longitudinal bars from the present study and the literature. This research investigates confinement of concrete obtained purely due to GFRP spirals. The contribution of the vertical reinforcement to confinement was avoided by using wooden dowels which did not provide appreciable strength under compression. In addition, this research investigates the ultimate tensile hoop strain of GFRP spirals. The equation derived for the confinement of concrete and axial strain of confined concrete can be used for design; additional research should be carried out for columns with a larger diameter and greater height than the columns used in this research.