AISC LRFD 1.pdf

App. F3.] WEB-TAPERED MEMBERS 103j = 2.5 / (a / h) 2 2 0.5(A-F2-4)Intermediate stiffeners are permitted to be stopped short of the tension flange, providedbearing is not needed to transmit a concentrated load or reaction. The weld bywhich intermediate stiffeners are attached to the web shall be terminated not lessthan four times nor more than six times the web thickness from the near toe of theweb-to-flange weld. When single stiffeners are used, they shall be attached to thecompression flange, if it consists of a rectangular plate, to resist any uplift tendencydue to torsion in the flange. When lateral bracing is attached to a stiffener, or a pairof stiffeners, these, in turn, shall be connected to the compression flange to transmitone percent of the total flange stress, unless the flange is composed only of angles.Bolts connecting stiffeners to the girder web shall be spaced not more than 12 in.(300 mm) on center. If intermittent fillet welds are used, the clear distance betweenwelds shall not be more than 16 times the web thickness nor more than 10 in. (250mm).F3. WEB-TAPERED MEMBERSThe design of tapered members meeting the requirements of this section shall begoverned by the provisions of Chapters D through H, except as modified by thisAppendix.1. General RequirementsIn order to qualify under this Specification, a tapered member shall meet the followingrequirements:(1) It shall possess at least one axis of symmetry, which shall be perpendicular tothe plane of bending if moments are present.(2) The flanges shall be of equal and constant area.(3) The depth shall vary linearly asæ z öd = d(A-F3-1)o ç 1+gè L÷øwhere = (d L - d o ) / d o the smaller of 0.268(L / d o ) or 6.0d o = depth at smaller end of member, in. (mm)d L = depth at larger end of member, in. (mm)z = distance from the smaller end of member, in. (mm)L = unbraced length of member measured between the center of gravity ofthe bracing members, in. (mm)2. Design Tensile StrengthThe design strength of tapered tension members shall be determined in accordancewith Section D1.3. Design Compressive StrengthThe design strength of tapered compression members shall be determined in accor-LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION