Influence of specimen geometry and size-effect on the KR-curve based on the cohesive stress in concrete

Comparative study for determining the KR-curves associated with the cohesive stress distribution for complete fracture process for two standard specimen geometries i.e., three-point bending test and compact tension test specimen geometries of concrete using analytical method and weight function approach is reported in the paper. The laboratory size specimen (100 ≤ D ≤ 400mm) with initial-notch length/depth ratios 0.3 and 0.5 are considered in the investigation. The load-crack opening displacement curves for these specimens are obtained using well known version of Fictitious Crack Model (FCM). It is found from the numerical results that the weight function method improves computational efficiency without any appreciable error. The stability analysis on the KR-curves and the influence of specimen geometry and the sizeeffect on the KR-curves, the CTOD-curves and the process zone length during crack propagation of complete fracture process are also described.