Summary: | Glass Fibre-Reinforced Polymer (GFRP) bars offer a feasible alternative in locations where steel is not the suitable reinforcement; namely locations that are sensitive to corrosion. In this study 60 specimens, 52 GFRP reinforced and 8 steel reinforced, were constructed and tested under direct tension in order to investigate the tension stiffening and cracking behaviour. The effects of different variables such as the bar type, the bar diameter, the reinforcement ratio and the concrete strength on tension stiffening and crack spacing were studied. The current code provisions for tension stiffening, namely ACI-440 and CEB-FIP were evaluated against the obtained test data. It was determined that the current code provisions significantly overestimate tension stiffening in GFRP reinforced specimens. A new tension stiffening model was, therefore, developed that provides better simulation of the test data. The CEB-FIP 1978 model for crack spacing was also modified for GFRP reinforced members.
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