Abstract
This paper presents the results of full-scale tests of welded beam-to-column subassemblies having two types of improved connection details: I.e., the reduced beam section (RBS) detail recommended in the US and no weld access hole detail adopted in Japan. Both types of connection modifications successfully prevented premature fracture, and exhibited nearly identical large energy dissipation capacity, although the strength of the RBS detail is smaller than that of the no weld access hole detail. This observation is reasoned from plastic strain distributions along the beam length as well as from contributions of the beam plastic rotation to the story drift.