Performance evaluation of high-strength concrete circular columns reinforced with GFRP bars and spirals
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Date
2021-05
Authors
Almomani, Mu'taz
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Abstract
The results of fifteen large-scale high-strength concrete (HSC) columns internally reinforced with GFRP bars and spirals are presented in this thesis. The concrete dimensions and reinforcement of the columns satisfied all the minimum requirements of the relevant Canadian standards. The test parameters in this study include reinforcement type (steel or GFRP), spiral pitch (50 or 85 mm), slenderness ratio (14, 20 or 28), the level of axial load eccentricity (60, 90, 120 or 150 mm) and the loading type (axial or flexural loading). The experimental results were then compared to the predictions of the Canadian and American FRP design codes and guidelines. Compared to the GFRP-reinforced concrete (RC) counterpart, the steel-RC specimen achieved a higher axial capacity (7.8%) with very similar behaviour up to the peak load but a more ductile post-peak behaviour. Both spiral pitches were able to provide adequate confinement up to the peak load, however, the smaller pitch was able to provide a more deformable post-peak behaviour. As the slenderness ratio increased, the lateral displacement increased and the lateral and axial stiffness decreased. The effect of increasing axial load eccentricity was more pronounced than the increase in slenderness ratio and resulted in reduced axial and lateral stiffness. The GFRP reinforcement was able to contribute to the carrying load capacity of both the axially-loaded columns and those under flexure. No failure of any bars or spirals was observed with the exception of the shortest column under the least eccentricity. Under flexural loading, the spirals were able to provide adequate confinement at different loading stages until failure. When compared with the experimental results, the examined codes and guidelines were found to be conservative in predicting the capacities of the columns for all loading conditions and slenderness ratios.
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Keywords
High-strength, Circular Columns, Eccentric, Flexural, Large-Scale, GFRP, spirals