Investigation of Bond Properties of Alternate Anchorage Schemes for Glass Fiber-Reinforced Polymer Bars

A study of existing research shows a need for an investigation of the bond properties of anchorage systems for glass fiber-reinforced polymer (GFRP) bars including mechanical anchor heads and bends. In this research program, the standard pullout test procedure was modified, which improved testing efficiency, accommodated bent bar tests, and reduced the variability of concrete properties across test specimens. Based on this experimental work consisting of a total of 72 specimens, it was concluded that the surface profile of GFRP bars influences only the post-peak phase of the bond stress-slip curve. It was also found that GFRP bars with anchor heads still require a considerable bonded length to develop the bars' full strength. The bend strengths were determined to be between 58 and 80% of the strength of the straight portion of the same bar in the specimens from three GFRP manufacturers. The straight bar embedment length required to develop full strength of bent bar was found to be approximately five times the bar diameter for all bar types tested.