Crack Width Formulas for Flexural Concrete Members Reinforced with Fiber-Reinforced Polymer Bars

Abstract:

To evaluate and calibrate the maximum crack width formulas for flexural concrete members reinforced with fiber-reinforced polymer （FRP） bars in current design standards， available literature on crack width tests of FRP reinforced concrete （RC） flexural members was extensively surveyed. After applying multiple filtering criteria， a database including 111 FRP-RC flexural members was developed. Then， the database was used to evaluate the accuracy of the crack width provisions from three design guidelines by comparing the tested widths with predictions. It was determined that GB 50608—2010 highly underestimated the maximum crack width， especially for the GFRP-RC and BFRP-RC members. In contrast， CJJ/T 280—2018 was more predictive than the other guidelines， while ACI 440.1R-15 provided conservative predictions. Based on this database， modifications were made to the non-uniform strain coefficient formula for tensile FRP bars in GB 50608—2010 by introducing an elastic modulus ratio E_f /E_s. Furthermore， the bond-dependent coefficients in the three design guidelines were calibrated to account for the effect of surface treatment.