Analysis of crack propagation in strain-softening beams

An analytical investigation for the propagation of cohesive cracks in a beam of quasi-brittle material such as concrete is presented using the fictitious crack model (FCM) developed by Hillerborg et al. for concrete. The stress–displacement relation is assumed as a generalized power law function. Expressions for moment–rotation relations are given. The analysis gives the effect of the softening exponent n on the size effect and snapback behavior of beams of softening materials. The effect of the elasticity co-efficient k of the central elastic layer on moment–rotation relation is also determined. A method to determine n and k from experiments is suggested.