Comparison of the shear behaviour of geopolymer concrete beams with GFRP and steel transverse reinforcements

Comparison of the shear behaviour of geopolymer concrete beams with GFRP and steel transverse reinforcements

This study presents a comparison of the shear behaviour of geopolymer concrete beams transversely reinforced with glass fiber-reinforced polymer (GFRP) and steel bars. Two full-scale beams with GFRP and steel stirrups spaced at 150 mm on-center were fabricated and tested up to failure using the four-point static bending test. Another beam without web reinforcements was also cast to determine the shear contribution of the geopolymer concrete. All the beams were provided with the same amount of flexural reinforcements. The beams were supported over a 1200 mm clear span with 450 mm shear span on each side. The shear span-to-depth ratio of the beams was 1.8. Based on the test results, the provision of GFRP stirrups almost doubled the shear capacity of the beam without web reinforcements. Comparable load-deflection response, shear strength, deflection capacity, and strain readings were observed between the beams with GFRP and steel stirrups. The two beams yielded similar crack pattern; however, wider cracks were developed in the former beam owing to the lower elastic modulus of GFRP bar compared with steel bar. Furthermore, both beams failed in shear, classified as a diagonal strut compression failure; however, the failure of the beam with GFRP stirrups was induced by the stirrup’s lap splice failure while steel yielding caused the failure of beam with steel stirrups. This had led to a more brittle final failure of the former beam compared with the latter beam.

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