This report summarizes an experimental program conducted to investigate the thermal and mechanical fatigue
effects on the bond between Glass Fiber-Reinforced Plastic (GFRP) rebars and concrete. Variables included in ihe
study were rebar diameter (No. 6 and No. 4 GFRP, No. 6 steel), material (steel and GFRP) and manufacturer (two
different manufactures for the GFRP rebar). For comparison, specimens were also fabricated using steel rebar as a
control. The embedment lengths were chosen so that a splitting failure was assured in all specimens.
A total of 30 inverted half-beam specimens were cast in 15 beams. Six specimens were mechanically tensiontension
cycled, twelve specimens were thermally cycled and twelve were used as control specimens (no thermal or
mechanical fatigue). During thermal fatigue, the rebars were also subjected to a constant tensile load to simulate
During the bond tests, specimens were loaded continuously until failure while monitoring load, free-end slip, and
loaded end slip. The results were evaluated to compare the bond performance of GFRP rebar to steel rebar, and to
determine the effects of thermal and mechanical fatigue on bond.
It was found that mechanical fatigue has more detrimental effect on steel that on GFRP specimens while thermal
fatigue has more effect on GFRP than on steel specimens. The effect of thermal fatigue was more in GFRP M2 than
in Ml specimens. The difference in bond performance between No. 6 and No. 4 GFRP Ml cannot be determined
form this study due to inferior product quality of the No. 4 M bars.
Retika, Annie Christine; Shield, Carol; French, Catherine.
Thermal and Mechanical Fatigue Effects on GFRP Rebar-concrete Bond.
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