BEF Analogy for Analysis of Box Girders

An analysis for a box girder cell with deformable cross section and flexible interior diaphragms is developed using an analogy to the theory of beams on elastic foundations. The analogy gives a clear view of the effects of box girder and diaphragm proportions on the longitudinal warping and transverse flexural stresses induced by deformation of the cross section. Conventional flexural and torsional analyses do not reveal these effects; complex, refined analyses do not give insight into box girder behavior. The analysis is applicable to straight box girders and accounts for longitudinally or transversely stiffened plate elements, nonprismatic sections, continuity over intermediate supports, and arbitrary end support conditions. The analogy provides a basis for a direct and rational approach to box girder design.