Effective Width of the Slab in Composite Beams with Nonlinear Shear Connection

Abstract

The stiffness and strength of a composite structure formed by a slab and an underlying beam made of different materials strongly depends on the shear coupling at their interface, which in general is not perfect because of the compliance of the shear connectors. The proposed approach interprets the effects of this partial interaction by establishing an equivalence, in terms of stress and deflection, with a composite beam with perfect shear bonding, but with a slab of smaller effective width. The method relies upon the minimization of the strain energy functional within a restricted class of shape functions for the deformation, finding the best approximation intermediate between the two limit cases of frictionless sliding and perfect shear coupling. If the response of the connectors is linear elastic, a simple formula is reached to calculate the effective width of the slab as a function of the static scheme and of the mechanical and geometrical properties. If the response is nonlinear, as it is in practice, the effective width is found by solving an algebraic equation, whose coefficients also depend on the magnitude of the applied load. Comparisons with numerical experiments confirm the very good accuracy of the proposed approach.