Column Web Cracking – Are You at Risk?

The Issue

Results of recent Charpy V-notch (CVN) testing performed on wide flange structural shapes of ASTM A572, Grade 50 steel have shown a wide variability in notch toughness. The web-flange transition region exhibited notch toughness in some instances or less than 5 ft-lb. These data are contrary to the recent AISC report which concluded that there is a high probability of the notch toughness exceeding 15 ft-lb at 70°F.¹ The low toughness, combined with high welding-induced constraint/restraint stresses, leads to cracking in the web-flange transition region. The low toughness and cracking occurred in Group 2, 3, and 4 wide flange columns.

The Answer

A variety of metallurgical and steel processing factors account for the variations in notch toughness observed in the web-flange transition, the ASTM A673, and the AISC "Core" locations. The cracking in this instance was eliminated by means of a redesigned cope and modified weld detail. Using finite element modeling, APTECH demonstrated that this solution would significantly reduce the residual/restraint stresses in the critical web-flange transition region. ¹ Catton, J., "Statistical Analysis of Charpy V-Notch Toughness for Steel Wide Flange Structural Shapes," Modern Steel Construction , Vol. 36, No. 5, pp. 38-44, 1996.

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