Fracture research on Welded Beam-Column Connection under Cyclic Loading

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The fracture process composed of ductile crack initiation followed by stable crack growth and finally explosive failure in the welded beam-to-column connections we investigated experimentally.Tested specimens were T-type connections consisted of the perimeter column and beam. The column was a rectangular hollow section (□-250x250x9), and the beam was H-section (BH-300x150x6x12). The test parameters were 1) welded access hole-in or out of existence of scallop 2) controlled displacement amplitude-1.0△_p to 2.5△_p.The results of fracture test of welded beam-column connections under cyclic loading were as follows ;1. Fracture of specimens were the fell wide failure of beam flange by the crack propagation from (1) the groove weld between the diaphragm and the beam flange in non-scallop type, (2) the bottom of scallop when the displacement-amplitude was over 1.5△_p, in scallop type.2. The beam strength fell to 80% of full-plastic-moment of beam when the crack length grew up to 20% to 40% of flange width.3. In the crack propagation rate relation dN/da = C(△J)^m, test results were m = 1.15 to 1.44 for non-scallop type, and m = 1.34 to 1.61 for scallop type.4. The fatigue life of the non-scallop type were about two times of one of scallop type, so it made clear that non the scallop type was available structural detail under the disastrous earthquake motion.