Abstract
It has been reported that steel structures such as bridges, ships and pressure vessels have broken down for the brittle fracture. On the other hand, there is some fear of the brittle fracture of tall buildings with the employment of heavy steel section members. Then, the brittle fracture was observed at the experiment of the full size beamcolumn connection under room temperature. The fracture of these steel frame constructions occures after large scale plastic yielding. Therefore linear elastic fracture mechanics can't accurately predict the fracture of the steel frame constructions. This paper deals with the fracture of steel structure beam-to-column connection with non-linear fracture mechanics. For non-linear fracture mechanics, COD fracture criterion and J_<IC> fracture criterion are proposed. But neither criteria have ever been established. We pay attention to J_<IC> criterion and will apply it to the fracture of steel structures. So first, we discuss the problems with which the determination of J_<IC> on experiment accompanies. And then, we examine the effectivity of the procedure of estimating the J-value by the finite element method analysis. The results are shown as follows, (1) It seems that J_<IC> can be employed for the constant of the material. (2) The procedure of estimating J-value by finite element method is sufficiently valid. (3) It is still more required to discuss about the determnation of the crack initiation displacement, δ_c.
