High or low cycle fatigue damage of buildings is caused by wind loading or seismic loading, respectively. In this study, cross welded joints were tested to clarify fatigue characteristics under high to low cycle condition. Effect of elastic stress concentration factor(K_t) on fatigue characteristics is clarified from the viewpoint of fatigue life(N_f) and crack initiation life(N_i). The results obtained are as follows : (1) Fatigue characteristics of the welded joints can be qualitatively predicted by using K_t of toe shape. (2) As K_t is higher and N_f is smaller, the ratio of N_i/N_f becomes smaller, and crack growth life(N_c) is dominant in N_f (3) In the case of high cycle fatigue, fatigue characteristics can be evaluated by using S-N curve and Miner's rule. In the case of low cycle fatigue, fatigue characteristics can be evaluated by using N_c from initial defect.
