Evaluation of the FIB bulletin 14 design guideline for external TRC bending reinforcement

Due to their advantages related to fire safety and their relatively low cost, Textile Reinforced Cement (TRC) composites are emerging as external reinforcing materials for concrete structures. The current design guidelines for external reinforcement are mostly elaborated for the Carbon Fibre Reinforced Polymers (CFRP) material solutions. Considering the major differences between both the CFRP and TRC materials, the validity of these CFRP design guidelines for the TRC external reinforcement should be verified and eventually the design rules should be adapted. This paper contributes to the evaluation of the European FIB bulletin 14 design guideline for TRC by comparing 2.3-meter-span externally reinforced concrete beams designed according to the FIB bulletin 14 with experimental results from four point bending tests. The results show that the design guidelines underestimate the ultimate load by almost 20 % due to a difference in occurring failure mode (experimental: failure in composite action; predicted: failure by loss of composite action). These observations indicate that the FIB design guideline cannot be used to accurately predict the bending behaviour of a TRC-reinforced beam and thus that adapted calculation techniques are needed.