Evaluation of major shear design codes and guidelines for FRP-reinforced members without stirrups

This paper provides a comprehensive overview of the current shear design methods, their developments, and the accuracy of the predictions for different types of FRP reinforced members. The existing shear design methods are evaluated based on 320 experimental test results of rectangular concrete beams and slabs. The test specimens were reinforced in the longitudinal direction by FRP bars only without transverse reinforcement. The test results are compared with the predictions of the previous versions of the current CSA, CHBDC, ACI, and AASHTO-LRFD design provisions. It has been observed that almost all methods predicted very conservative and inconsistent results, with mean values of experimental to predicted capacities varying from 2.32 to 9.71. It has been found that the accuracy of the predictions of the current models is increased compared to the corresponding previous models with the values ranging from 1.99 to 3.24. In addition to these current provisions, four other models such as JSCE, BISE, CNR-DT 203 and ISIS-M03 are also examined. Although some of the models showed improvements in their predictions, there are still significant variations in the trends of predictions for different parameters. Among the eight models, the predictions of CSA S806 are better than those of the other methods for combined GFRP and CFRP members followed by CNR-DT 203. When comparisons are made separately for GFRP and CFRP-reinforced members, it becomes evident that the predictions for CFRP-reinforced members consistently outperform those for GFRP-reinforced members across all methods. This is attributed to the fact that most of the design equations are derived from steel-reinforced members and that the modulus of elasticity of CFRP is close to that of steel bars. On the other hand, the predictions have improved significantly for members with shear span to depth ratio greater than 2.5 irrespective of the FRP type. Further study is necessary to refine the models and enhance prediction accuracy for various types of FRP reinforced members.