AISC LRFD 1.pdf

54 WELDS [Sect. J2.TABLE J2.4Minimum Size of Fillet WeldsMaterial Thickness ofThicker Part Joined, in. (mm)To 1 4 (6) inclusiveOver 1 4 (6) to 1 2 (13)Over 1 2 (13) to 3 4 (19)Over 3 4 (19)[a] Leg dimension of fillet welds. Single pass welds must be used.[b] See Section J2.2b for maximum size of fillet welds.Minimum Size ofFillet Weld[a] in. (mm)1 8 (3)3 16 (5)1 4 (6)5 16 (8)taken equal to the leg size for 3 8-in. (10 mm) and smaller fillet welds, and equal tothe theoretical throat plus 0.11-in. (3 mm) for fillet welds over 3 8-in.(10 mm).For fillet welds in holes and slots, the effective length shall be the length of thecenterline of the weld along the center of the plane through the throat. In the case ofoverlapping fillets, the effective area shall not exceed the nominal cross-sectionalarea of the hole or slot, in the plane of the faying surface.2b. LimitationsThe minimum size of fillet welds shall be not less than the size required to transmitcalculated forces nor the size as shown in Table J2.4 which is based upon experiencesand provides some margin for uncalculated stress encountered during fabrication,handling, transportation, and erection. These provisions do not apply tofillet weld reinforcements of partial- or complete-joint-penetration welds.The maximum size of fillet welds of connected parts shall be:(a) Along edges of material less than 1 4-in. (6 mm) thick, not greater than the thicknessof the material.(b) Along edges of material 1 4-in. (6 mm) or more in thickness, not greater than thethickness of the material minus 1 16-in. (2 mm), unless the weld is especiallydesignated on the drawings to be built out to obtain full-throat thickness. In theas-welded condition, the distance between the edge of the base metal and thetoe of the weld is permitted to be less than 1 16-in. (2 mm) provided the weld sizeis clearly verifiable.For flange-web welds and similar connections, the actual weld size need not belarger than that required to develop the web capacity, and the requirements of TableJ2.4 need not apply.The minimum effective length of fillet welds designed on the basis of strength shallbe not less than four times the nominal size, or else the size of the weld shall beconsidered not to exceed 1 4 of its effective length. If longitudinal fillet welds areused alone in end connections of flat-bar tension members, the length of each filletweld shall be not less than the perpendicular distance between them. For the effectof longitudinal fillet weld length in end connections upon the effective area of theconnected member, see Section B3.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION