This paper targets steel beam to box-section column connections with exterior diaphragms whose depth are smaller than those of conventional ones. An evaluation method of yield strength of beam flange connections is proposed considering partial penetration welds of the exterior diaphragm. Mechanical behavior and effects of parameters on yield strength of connections are examined by a loading test and finite element analysis. As a result, it is clarified that calculated values based on the evaluation method can correspond to results of the test and the analysis within ±10% errors.
