Moment redistribution in CFRP strengthened concrete t-beams: an experimental study

Moment redistribution in FRP flexurally strengthened continuous reinforced concrete structures is often not allowed (or is limited) in design guidance documents. This is due to the elastic-brittle nature of CFRP composite materials and their propensity to prematurely debond from the concrete surface, resulting in a reduction in the associated ductility of the strengthened concrete section. However, there is still a possibility that some redistribution can occur if sufficient rotation capacity can develop. In this study, the moment redistribution capacity of FRP strengthened RC T-beams was examined by testing 6 two-span continuous specimens. The specimens were designed to have 30% redistribution capacity before FRP strengthening. Different internal steel arrangements as well as various FRP strengthening configurations and anchoring schemes were investigated for each specimen. The experimental results demonstrated that a high amount of moment redistribution could be achieved into FRP-strengthened zones, with little restriction, while the degree of moment redistribution out of FRP-strengthened zones is highly dependent on the quantity and anchorage of the CFRP composite materials, although some limited but significant moment redistribution is generally still possible.