Bond Behavior of a CFRP Strengthening System for Steel Structures

This paper summarizes an experimental program supported by an analytical modeling study undertaken to investigate the bond behavior of carbon fiber reinforced polymer (CFRP) materials used for strengthening steel structures. The experimental program consisted of three double-lap shear coupon tests and five large-scale beam tests. Different methods to reduce the bond stress concentrations near the plate ends were investigated including increasing the length of the splice cover plate and implementing a reverse-tapered plate end configuration. Three-dimensional linear and non-linear finite element analysis (FEA) was conducted to study the cracking behavior of the splice joints and to determine the effect of the reverse-taper on the interface shear and normal (peeling) stress distributions near the plate ends. The research findings indicate that implementation of the reverse taper at the plate ends can double the splice capacity as compared to conventional square plate ends. Based on the research findings simple design recommendations are presented to increase the ultimate capacity of splice joints. This paper demonstrates that splice joints can be effectively implemented to facilitate the use of CFRP strengthening systems for strengthening and repair of long-span steel beams.