Bond Behavior of Post-Installed GFRP Bars in Structural Connections

Abstract

This research presents an experimental study with GFRP bars from three manufacturers, each having different bar textures (silica coated with helical wraps, silica coated and ribbed) used as post-installed (epoxy and cementitious adhesive) and cast-in-place reinforcement. Twenty test specimens were constructed and tested under static load. A test specimen was composed of two identical vertical elements, which were anchored into the base of the specimen using post-installed GFRP bars. The variables tested among different specimens included: concrete compressive strength (3 and 6 ksi), embedment length of GFRP bars (6 and 11.5 in.), and size of the post-installed GFRP bars (#4, #6, and #8). Concrete breakout was the only failure mode in all of the specimens with post-installed GFRP. Bond strengths and peak applied loads improved by increasing concrete strengths and embedment depths. The larger diameter bars (#6 and #8) showed a loss of bond strength compared to #4 bars.