骨組構造物における溶接欠陥を持つ部材の全面降伏後破壊性能に関する研究 ＩＩ

Abstract

Authors have carried out experiments and analyses of welded joints with defects under limited conditions that a joint width was 100 mm and defects were through-thickness notches. Therefore, in this report, the results of another various static tensile tests are discribed. As for another influence factors on joints performance, defect location, joint width and part-through-thickness defects are examined. In the present experiments, low-toughness weld metal is used to make fracture mode of almost specimens brittle even at room temperature.One-side notched specimens show lower ductility and strength as compared with center notched and both-sides notched specimens. This results is attributed to a bending moment induced by asymmetric shape in case of one-side notched specimens. Tensile tests are carried out with specimens of 100 mm, 200 mm and 400 mm in width. Both fracture strain (G.L. =30 mm) and strength decrease with increasing joint width.No appreciable defference in fracture strain and strength is observed between specimens with mechanical notches and those with lack of penetration type defects.From view point of ductility, the equivalent through-thickness defect length (2â) of specimen having part-through-thickness defect (2a: length, t1: depth, t: joint thickness) can be estimated byâ/a=2⋅(t1/t)2 for 0.2<t1/t<0.6.Overall strain(ε∞)-non dimensional COD(δ'=δ/2κεyα) relation for welded components with defects in steel framed structure is given byδ'=δ/2κεyâ=0.6⋅(ε∞/εy)This equation gives approximatly upper limit to experimental results.As critical COD obtained by small bending COD test is smaller than critical COD obtained by tensile tests, it is appropriate to evaluate weld defects by critical COD obtained by small bending COD test and the previous equation.