Analytical model of flexural performance for GFRP-reinforced concrete beams with constitutive model developed for new compression yielding (CY) block

The compression yielding (CY) concept has proven to be an effective method for improving the insufficient flexural ductility of fiber-reinforced polymer reinforced concrete (FRP-RC) beams caused by the linear stress-strain characteristics of FRP bars. However, traditional CY materials exhibit limited variability in mechanical properties, particularly in terms of compressive strength, and they face durability issues. To address these challenges, this study introduces a novel CY block, developed by the authors, using PET FRP-confined engineered cementitious composite (ECC) with compression ductility as high as 25.81, meeting the requirement of CY blocks for compression ductility of no less than 20. This material makes it a suitable candidate for enhancing the performance of FRP-RC beams. Based on this, a design-oriented stress-strain model for the PET FRP-confined ECC was developed, followed by a validated analytical model of the flexural behavior of GFRP-RC beams with this CY block (briefly named as CY beam). The results indicate that the balanced reinforcement ratio for the CY beam is directly proportional to the height of the CY block, and the ultimate moment and curvature of the CY beam are enhanced by up to 56 % and 210 %, respectively, compared to conventional FRP-RC beams. Moreover, the deflection ductility of CY beams reaches 3–4 through reasonable design.