| Budget Amount *help |
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2004: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2003: ¥10,900,000 (Direct Cost: ¥10,900,000)
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| Research Abstract |
The welding defect of the welding connection in steel structure causes the brittle fracture. This paper presents the results of tests and analysis conducted to investigate the influence of fracture toughness and weld defect size. The obtained finding is shown below.
The welding defect have a much greater impact on deformation capacity. As evaluation methods of welding defect, equivalent clack size A is effective methods for evaluating deformation capacity of beam-to-column joints. Next, this study researched effect of the yield rate of beam flange and toughness of diaphragm on the deformation capacity of beam to column weld connection with defects. The experimental results show the deformation capacity of beam to column weld connection with defects is influenced by the yield rate of beam flange. The lower yield rate of the beam flange, the higher the deformation capacity of beam to column connection. About toughness of diaphragm, 0℃ Charpy absorption energy of part of HAZ that was the f
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racture starting point rose by the beat influence of the welding. Therefore, no remarkable difference in the range of the actual experiment. About effect of defect size, there is no decrease in the deformation capacity when A is less or equal 8mm. Oppositely, the possession performance begins to decrease when A is exceeded 8mm. If a present Ultrasonic standard is replaced with the equivalent crack size, it becomes about A=4.47-7.04. Therefore, it is thought that a present Ultrasonic standard evaluates the safety side.
Next, this study experimented tensile test to quantitatively understand of weld defects and to compare of the internal deflects with the edge defects. As a result, weld joint with the internal defects is stronger than weld joint with the edge defects. As for length, it has been understood it has about twice the amount of the deformation in about 1.5times to twice length at the edge defects about internal defects. When defect height is no less than 70% of thickness of flange, it is identify with the through thickness weld defect. Oppositely, when defect height is no more than 20% of thickness of flange, it have low impact the deformation capacity.
Finally, it is believed that this study could suggest the effective and realistic limits of size. Less
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