AISC LRFD 1.pdf

271Comm. A-GAPPENDIX GPLATE GIRDERSAppendix G is taken from AISI Bulletin 27 (Galambos, 1978). Comparable provisionsare included in the AISC ASD Specification. The provisions are presented in an appendixas they are seldom used and produce designs which are often less economical than plategirders designed without tension-field action.The web slenderness ratio h/t w = 570 . E/F yf that distinguishes plate girders frombeams is written in terms of the flange yield stress, because for hybrid girders inelasticbuckling of the web due to bending depends on the flange strain.The equation for R e used in the 1986 LRFD Specification was the same as that used in theAASHTO Standard Specification for Highway Bridges. In this edition, the equation forR e , used in the AISC ASD Specification since 1969, is used because its derivation is published(Gaylord, Gaylord, and Stallmeyer, 1992 and Joint ASCE-AASHTO Committeeon Flexural Members, 1968) and it is more accurate than the AASHTO equation.G2. DESIGN FLEXURAL STRENGTHIn previous versions of the AISC Specification a coefficient of 0.0005a r was used inR PG based on the work of Basler (1961). This value is valid for a r 2. In that samepaper, Basler developed a more general coefficient, applicable to all ratios of A w /A fwhich has been adopted because application of the previous equation to sectionswith large a r values gives unreasonable results. An arbitrary limit of a r 10 isimposed so that the R PG expression is not applied to sections approaching a teeshape.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION