A simplified approach to assess the size effect on the shear-flexure interaction in RC elements

Following the concept of design capacity, the main purpose of the structural design of RC elements is to avoid brittle failures and to ensure ductile behavior. Under cyclic loading, the shear strength is reduced by increasing the flexural ductility. A good estimation of the failure mode of RC elements exhibiting a shear-flexural interaction relies on a good estimation of the flexural capacity (strength and ductility) and the shear capacity. In the present paper, a simplified model is proposed to describe the flexural behavior. The size effect is taken into account for the assessment of the flexural ductility. On the other hand, based on a comparative study of existing shear capacity models, a shear capacity formula is proposed to evaluate the shear strength and the shear reduction. The failure mode prediction is assessed following the ATC (Applied Technology Council) conceptual model. Comparison with experimental tests shows the ability of the proposed approach to predict the failure mode and the corresponding ductility.