Design of Hybrid Steel Beams

Abstract

The available theoretical and experimental information on composite and noncomposite hybrid steel beams and girders, is used by Subcommittee 1 on Hybrid Beams and Girders of the Joint ASCE-AASHO Committee on Flexural Members as a basis for design suggestions for such members. The Subcommittee concluded that composite and noncomposite hybrid steel beams can be efficiently designed on the basis of the initial flange-yield moment. Specifically, an allowable flange stress that is slightly below the allowable stress normally used for the flange steel can be applied and the bending stress in the web need not be checked. The shear stress in the web, however, must be limited to the normal allowable stress for the web steel. The allowable width-to-thickness ratios and stiffener requirements are generally the same as those given in the AISC and AASHO specifications for homogeneous beams. Available data indicate that hybrid beams can generally be designed for fatigue as if they were fabricated homogeneous beams of the flange steel.