Shear-flexural cracking strength of RC beams with external vertical prestressing rebars: Theoretical investigation and numerical simulation

This paper presents a semi-theoretical empirical formula to predict the shear-flexural cracking strength of an RC beam enhanced with the external vertical prestressing rebar (EVPR) technique. Besides, nonlinear finite element models (FEM) created by software ABAQUS were used to analyze the effect of crucial parameters on the shear-flexural cracking strength. The parameters involve shear span-to-depth ratio, concrete strength, longitudinal tension reinforcement ratio, initial pulling force and spacing of EVPRs, and the vertical stiffness of the EVPR supports. Results show that the cracking strength increased linearly with the tensile strength of the concrete and the initial pulling force. The small shear span-to-depth ratio was predominantly conducive to the cracking strength. Adequate longitudinal tension rebars contributed to the cracking strength improvement. A reasonable EVPR spacing was recommended to ensure the cracking strength. Greater vertical stiffness of the EVPR supports can ensure higher compressive stress for the RC beam to improve the cracking strength.