Bond behavior between GFRP rod and concrete subjected to high stress reversals

Twenty standard bond specimens of GFRP rod were tested under monotonic load and cyclic load to studythe changes of bond st rength , the slip at the loaded end , unloading stiffness and hysteretic energy dissipation. Theresult s indicate that the GFRP rod does not exhibit steady bond behavior under constant stress reversals (Δτ=017τu ) , and the bond st rength of the specimens subjected to variable st ress reversals degrades significantly as cyclesincrease. The envelop curves and the common-point curves show basically the same profile as thoseτ s curves fromthe monotonic static test . The ratios of the bond st resses in the common-point curves to those in the envelop curvesat the same slip range f rom 0. 50 to 0. 75. More serious damage can be observed around the ribs of the GFRP rod inthe specimens after stress reversals than those subjected to monotonic static test . No splitting cracks can be seen inthe concrete. From the investigation of the slip at the loaded end , hysteretic energy dissipation and unloading stiffness asreversals increase , the load history and accumulative damage status were found to be the two key influencing factors.