Numerical Investigation of the Shear Strength of RC Deep Beams Using the Microplane Model

Abstract

Although much work has been done on the shear behavior of RC elements, current design provisions are still based on empirical data and their predictions, especially for deep beams, are not always reliable and can lead to unconservative results. This paper presents an extensive numerical investigation on the role of key parameters on the shear performance of RC deep beams using the microplane M4 material model. The model is validated against experimental results of 20 RC deep beams. A parametric study is then carried out to investigate the effect of shear span to depth ratio and concrete compressive strength for RC deep beams with and without shear reinforcement. Although a single strut mechanism is generally mobilized in deep beams, the presence of shear reinforcement can enable a more uniform distribution of shear stresses within the shear span and enhance the effectiveness of concrete cracked in tension. The study confirms that both shear span to depth ratio and concrete strength are the key parameters that affect the shear capacity of RC deep beams and should be taken into account in code equations.