AISC LRFD 1.pdf

Comm. J2.] WELDS 239(b) Plane 2-2, in which the resistance is governed by the shear strength of the weldmetal.(c) Plane 3-3, in which the resistance is governed by the shear strength of the materialB.The resistance of the welded joint is the lowest of the resistance calculated in eachplane of shear transfer. Note that planes 1-1 and 3-3 are positioned away from thefusion areas between the weld and the base material. Tests have demonstrated thatthe stress on this fusion area is not critical in determining the shear strength of filletwelds (Preece, 1968).The shear planes for plug and partial-joint-penetration groove welds are shown inFigure C-J2.11 for the weld and base metal. Generally the base metal will governthe shear strength.5. Combination of WeldsThis method of adding weld strengths does not apply to a welded joint using a partial-joint-penetrationsingle bevel groove weld with a superimposed fillet weld. Inthis case, the effective throat of the combined joint must be determined and thedesign strength based upon this throat area.6. Weld Metal RequirementsApplied and residual stresses and geometrical discontinuities from back-up barswith associated notch effects contribute to sensitivity to fracture. Some weld metalsin combination with certain procedures result in welds with low notch toughness.The Specification requires a minimum specified toughness for weld metals in thosejoints that are subject to more significant applied stresses and toughness demands.The level of toughness required was selected as one level more conservative thanFig. C-J2.11. Shear planes for plug and partial-joint-penetration groove welds.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION