Specimen size effect on the brittle fracture properties of steel for buildings subjected to large earthquakes

Abstract In recent years, as the height and size of building layers have increased, the thicknesses of the components used have also increased, making brittle fracture more likely to occur. Fracture tests have often been performed on reduced scale steel. It is necessary to develop an approach for brittle fracture evaluation that is less sensitive to the specimen size. In this study, we focused on the relationship between brittle fracture properties and geometrical shape and conducted a three-point bending test for isometric specimens with a 4:2:1 geometry. The results of the three-point bending tests were organized by quasi-CTOD, and it was found that the results were affected by the specimen size and notch depth. The modified Weibull stress model based on the local approach was able to evaluate the critical conditions of brittle fracture in a unified manner. Fracture probabilities at the initiation point of brittle fracture were defined and applied to each Weibull stress model, and the results were validated. The plastic strain distribution and microcrack appearance suggest the involvement of triaxiality in crack initiation. The inclusion of triaxiality in the fracture probability makes the initiation of brittle fracture more likely, and it suggests the possibility of including multiaxiality in the local approach.