Investigation of glass-fibre-reinforced-polymer shells as formwork and reinforcement for concrete columns
An investigation was conducted to study the behaviour of full-scale concrete-filled glass-fibre-reinforced-polymer (GFRP) shells under concentric compression. The main objective was to assess the suitability of prefabricated GFRP shells for stay-in-place formwork and confining reinforcement for columns. Seventeen columns, 356 mm in diameter and 1524 mm long were tested. The nominal target concrete compressive strength at 28 d was 30 MPa. Variables examined included number of GFRP layers, fibre orientation, and amount of longitudinal and lateral steel. Confinement by GFRP shells resulted in concrete response that displayed increased strength and associated strain followed by a ductile descending branch. Fibres in the longitudinal direction improved the load-carrying capacity of the columns, but the increase was less than the capacity of the fibres determined from the tension tests. Glass-fibre-reinforced-polymer shells also eliminate the need for closely spaced confinement steel, which should improve the quality of construction. In addition to ease of construction, GFRP shells provide protection against environmental effects, thus helping to reduce life cycle costs.Key words: columns, confinement, stay-in-place formwork, strength, ductility, energy capacity, earthquake, seismic resistance, lateral reinforcement, glass-fibre-reinforced-polymer (GFRP) shell.