Abstract
Many fatigue cracks were found in beam-to-column connections in steel bridge frame piers in Metropolitan high-ways. In this study, the investigations on fatigue performance of beam-to-column connections with box sections were conducted by experiments and FEM analysis. From the results, it was pointed out that in fatigue design of the connections, it is necessary to consider the high stress concentration occurred at the edges of flange plates. And it came to be clear that in welded joints at the connections, unwelded zones could be included due to partial penetration, and that they could cause the low fatigue strength of the connections. For that reason, full penetration welding should be applied to avoid the introduction of unwelded zones.
