Theoretical model to predict the flexural response of concrete beams pre-tensioned with CFRP rods considering CFRP slippage effects

Abstract

The overwhelming costs of maintenance for reinforced concrete structures due to steel corrosion have motivated researchers to look for alternatives. One of the promising alternatives is Fiber Reinforced Polymer (FRP). Among FRP materials, Carbon FRP (CFRP) is the most attractive material for prestressed concrete members due to its high tensile strength and modulus of elasticity. Previous studies investigated the use of CFRP in prestressed concrete through experimental tests and theoretical analysis. However, there is a significant need for more experimental data to develop an accurate model that can accurately predict the behavior of CFRP prestressed concrete beams. In the current study, experimental flexural tests were conducted on four prestressed concrete beams pre-tensioned with CFRP rods. The length of the beams was 4,270 mm, and the cross-sectional dimensions were 138 x 250 mm. All the beams were subjected to four-point loading with an initial five cycles of loading and unloading before a monotonic loading until failure. Their performance was analyzed, and based on the results a theoretical model was proposed. It was found that the slippage of CFRP at the ends significantly affect the flexural behavior and failure modes of the beams. Additionally, theoretical models must account for CFRP slippage at the ends to accurately predict the flexural response of CFRP prestressed concrete beams. When a slippage reduction factor was used in the proposed theoretical model, the results had a good agreement with the experimental tests. Future research may focus on testing the theoretical model with more data from experimental studies.