Comparative analysis of shear capacity of reinforced concrete beams according to design standards

Abstract

The shear capacity of reinforced concrete beams is influenced by multiple factors. Currently, different design standards worldwide adopt various approaches to calculating the shear strength of reinforced concrete beams, including the strut-and-tie model (STM), compression stress field theory (CSFT), and semi-empirical models, among others. Most reinforced concrete design standards consider only the shear resistance provided by concrete and stirrups while neglecting the influence of other factors. This often results in overly conservative calculations. This paper provides an overview of several shear strength calculation models for reinforced concrete beams based on different design standards, including TCVN 5574:2018, ACI 318, CSA A23.3, and EN 1992-1-1:2004. These models are validated against an experimental dataset comprising 59 reinforced concrete beams subjected to concentrated loads, with the ratio of shear span to effective depth (a/d) ranging from 2.5 to 4.0. In this study, the shear contributions of concrete and stirrups are separately evaluated for each standard. Additionally, the concrete shear capacity is compared with the shear strength of corresponding beams without stirrups, calculated based on the Critical Shear Crack Theory (CSCT). The results indicate that among the four considered design standards, EN 1992-1-1:2004 provides the most conservative estimates, while TCVN 5574:2018 yields results closest to the experimental data. Moreover, TCVN 5574:2018 assesses the shear contribution of concrete similarly to the shear strength of corresponding beams without stirrups.

Keywords: Beam; reinforced concrete; shear strength; design standards