Shear deformation in reinforced concrete beams with thin web

In this paper the main results of an experimental campaign, carried out to analyse the shear deformation and interaction between moment and shear on the global and local deformations of reinforced concrete (RC) ‘I’ section simply supported beams with thin web, are discussed. A new theoretical model, which considers the lattice-like behaviour and applies the constitutive laws of the modified compressive field theory, is also proposed. The ‘concrete contribution’ of shear strength resistance is theoretically calculated. Experimental and theoretical results are then compared, showing the rotation of the principal compressive strain axis in the web. The influence of shear deformation on the deflection of the tested beams with thin web reaches 25% of the total deflection.