Shear Behavior of Concrete Beams Reinforced with Hybrid (GFRP and Steel) Bars Without Stirrups

Abstract:

This paper evaluates the shear behavior of hybrid GFRP/steel-reinforced concrete beams without transverse reinforcement.All beams were subjected to four-point loading,with shear span-to-effective depth ratio of 2.54 and 2.67 respectively.The test variables were effective reinforcement ratio and axial stiffness ratio between GFRP and steel bars.The test beams included three beams reinforced with steel bars,three beams reinforced with GFRP bars and six beams reinforced with GFRP and steel bars.An analysis was made of the load-midspan deflection curves,cracking behavior and shear strength of tested beams.The test results were compared with the predictions provided by different codes and design guidelines available.The test result shows that beams designed with the same effective reinforcement ratio,exhibits similar shear strength regardless of reinforcement arrangement (steel，GFRP，or combination of steel and GFRP).Axial stiffness ratio between GFRP and steel bars has little influence on shear behavior of hybrid GFRP/steel-reinforced concrete beams.Eurocode 2—04 and CSA A23.3—04 design method provids reasonable predictions,whereas the ACI440.1R—06,JSCE and CSA S6—06 results in conservative shear strength estimates.