Højkvalitetsbetoner i 90'erne / High Performance Concretes in the 90'es:Report 4.2 : Analytical Model for Complete Moment-Rotation Curves of Concrete Beams in Bending

When a concrete beam is subjected to rotation controlled static loading a linear cohesive crack is assumed to develop in the tensile side of the midsection of the beam. As a first approximation the two parts of the beam beyond the cohesive crack zone are assumed to perform rigid-body displacements. An elastic layer is introduced between the crack and the rigid parts of the beam. The stress distribution in the layer is assumed to be local and to be a function of the absolute displacement between the two rigid bodies. An improved model accounts for the elastic deformation of the beam via a Timoshenko beam. Different, geometrically similar, beams with constant constitutive parameters have been tested and it is shown that the moment rotation curves from the analytical model only differ slightly from the ones determined through a finite element analysis