MODELING OF BOND BEHAVIOR OF HYBRID RODS FOR CONCRETE REINFORCEMENT

Fiber reinforced plastic (FRP) rods are used as reinforcement (prestre ssed or not) to concrete. FRP composites can also be combined with ste el to form hybrid reinforcing rods that take advantage of the properti es of both materials. In order to effectively utilize these rods, thei r bond behavior with concrete must be understood. The objective of thi s study is to characterize and model the bond behavior of hybrid FRP r ods made with epoxy-impregnated aramid or poly-vinyl alcohol FRP skins directly braided onto a steel core. The model closely examines the sp lit failure of the concrete by quantifying the relationship between sl ip of the rods resulting transverse stress field in concrete. The mode l is used to derive coefficients of friction for these rods and, from these, their development length requirements. More testing is needed t o confirm this model, but in the interim, it may serve as a design aid e, allowing intelligent decisions regarding concrete cover and develop ment length. As such, this model has helped to explain and predict som e experimental data from concentric pull-out tests of hybrid FRP rods.