A Simplified Method for the Flexural Design of Stiffened Hybrid Girders

Abstract

Hybrid girders are useful when strength is the governing factor in design. Due to the availability of higher strength steels and their structural efficiency, hybrid beams and girders are becoming more and more popular. The behavior of hybrid beams has been under extensive research and reported in various publications. However, there is still very little literature available on the design of hybrid beams. In 1970, Milek presented a comprehensive paper on hybrid girder design according to the 1969 AISC Specification. Recently, Schilling has published a paper which explores the optimal dimensions of both homogeneous and hybrid I-shaped beams due to bending moment only (web slenderness is assumed to be known). The theory and simplified method presented herein consider full unadjusted allowable bending stress in conjunction with reduced web contribution to the section modulus. The Adventage of this exact approach in flexural design of hybrid girders is that the dependency on b (ratio of web area to one flange area) is eliminated. Thus, no guesswork is required and no iterations are performed with respect to b. In other words a direct flexural design is possible by the simplified method. The method can also be applied for the analysis of a hybrid girder when the cross section is given