Theory and Applications of the Lifting of Elastic, Doubly Symmetric, Horizontally Curved Beams

The lifting of horizontally curved beams (or almost-straight beams with an imperfection in shape) is considered, with application in the construction of bridges. A circularly curved beam that is suspended at two symmetric locations by vertical or inclined cables is analyzed. The cross section of the beam is assumed to be doubly symmetric, the material is assumed to be linearly elastic, the cross-sectional dimensions are assumed to be small relative to the radius of curvature, and the deformations are assumed to be small. Both uniform (St. Venant) torsion and inclusion of nonuniform (warping) torsion are treated. Analytical equations are derived for the overall roll angle of the beam, the internal forces and moments, the weak-axis and strong-axis deflections, and the cross-sectional angle of twist. The behavior depends crucially on the locations of the lift points.