The pre-cracked hybrid GFRP-steel RC beams strengthened with CFRP sheet: experiment and strength prediction.

AbstractThis paper tests four pre-cracked hybrid GFRP-steel reinforced concrete (HGSRC) beams with CFRP sheets and four intact reference beams under four-point bending to examine the effects of CFRP sheets and steel reinforcement ratios on flexural behavior. The pre-crack width caused by the load is approximately 0.2 mm. The experiments showed that the addition of CFRP sheets transformed the failure mode of the pre-cracked HGSRC beams from shear compression to delamination-plate-end-debonding and resulted in a reduction of up to 54% in their energy ductility index. The incorporation of CFRP sheets significantly enhanced the flexural behavior of pre-damaged HGSRC beams in terms of yielding load and secondary stiffness, while the improvement in their load-carrying capacity was minimal was slight. The addition of CFRP sheets could also delay the development of strains in materials even though the beams were pre-cracked. The analytical models to determine the load-carrying capacity of pre-cracked HGSRC beams strengthened with CFRP sheets are still limited and therefore, a strut-and-tie model (STM) is proposed to fill the gap in this research. The integration of corrected formulas into the strut and tie model for estimating the load-bearing capacity of the pre-cracked strengthened HGSRC beams indicated a strong agreement with the experimental data. [ABSTRACT FROM AUTHOR]