Verification of Truss-Arch model unified for RC beams with stirrups using shear database

Abstract

A shear strength analysis model called “Truss-Arch Model Unified (TAMU)” was proposed for shear-critical reinforced concrete (RC) beams with transverse reinforcement. The TAMU has its roots in the Compatibility Strut-and-Tie Model (C-STM) which is a computational modeling approach for the overall force–deformation analysis of deep beams. The TAMU simplified the C-STM so that a limited analysis can be executed by hand methods of analysis to predict the maximum load-carrying capacity of RC deep beams. While the tensile stress of concrete is generally taken into account to evaluate the shear strength of RC beams, the TAMU limit analysis focuses on the strength reduction of the principal diagonal concrete arch due to the transverse principal tensile strain. In the present study, a shear database is assembled from previous works reported in the literature to further substantiate the validity of the TAMU approach. The shear database consists of tested RC beams with shear reinforcement whose shear span-depth ratios (a/d) are between 0.5 and 4.5. Comparative TAMU analysis results show satisfactory agreement with the ultimate strengths observed in 460 RC beam tests regardless of D- and B-regions, demonstrating the method’s ability to predict the maximum load-carrying capacity for shear-critical beams. Additionally, the TAMU approach shows better accuracy and consistency against the database compared to AASHTO sectional shear design methods. The probability of reasonable prediction of the TAMU method is 92% in d-regions and 78% in B-regions, respectively, which is significantly higher than those of AASHTO sectional shear design methods, especially in d-regions. Thus, the TAMU method may be a viable improvement as an alternative strength analysis method for shear-critical RC beams with transverse reinforcement.