This study is aimed to investigate cracking mechanism of steel members under cyclic bending. The process of crack initiation and propagation in the seven specimens are studied. The effects of notch shape and cyclic loading pattern on ductile fracture of the specimens are discussed. A large radius notch can delay crack initiation and propagation. Also, differences in loading pattern affect crack initiation and propagation. Therefore, the strength, cumulative ductility ratio and energy absorption of the specimens show different results depending on the notch shape and loading pattern.
