Crack growth in concrete slab resting on steel beam: softening and damage accumulation

Analyzed in this work is the four-point bending of a concrete slab supported by a steel beam. An edge crack is assumed to prevail on the tension side of the concrete that would grow gradually while the overall stiffness and local fracture toughness of the concrete would also degrade as damage accumulates. The latter two quantities are assumed to decrease with increasing deflection of the composite system. These effects are incorporated into the strain energy density criterion that can simultaneously predict crack initiation and growth including the event of final termination. Numerical results on load and deflection are obtained for two different composite concrete/steel beam systems such that the prevailing geometric material and loading parameters are accounted for as a combination. The distances between the local and global stationary values of the volume energy density are also determined as an indication of fracture instability. An edge crack tends to extend more stably as the compressive zone ahead increases with deflection of the composite beam.