DETERMINATION OF BOUDNARY EFFECT ON FRACTURE ENERGY OF CONCRETE

Fracture properties along ligament length are investigated by considering the influence of specimen boundary condition. An explanation is presented for the specimen size effect on specific fracture energy observed in experiments. Based on the explanation, a model for size-independent fracture energy is provided by introducing a concept of local fracture energy. Wedge splitting tests and experimental results from three-point bending tests available in literature were used to verify the proposed model. It is shown that the local fracture energy spread in a non-uniform manner along the ligament length when the specimen failed, which led to the size-dependence of the traditional fracture energy. Furthermore, the computed value of the proposed fracture energy was kept approximately constant irrespective of the specimen size. The parameter reflecting the boundary influence, however, was size dependent.