In the 1995 Hyougoken-Nanbu earthquake, brittle fractures of beam flange in the vicinity of beam-to- boxed column moment resisting connections were widely observed. One cause is stress concentration of the welded part at the connection. Therefore, horizontal haunched beam is proposed to relieve the high stress by increasing the flange area. In this paper, seven simple beamtype specimens with various haunch lengths were statically loaded. Based on the test results, effective haunch shapes, i.e., the length and the angle, are proposed to avoid brittle fractures and increase deformation capacity.
