Shear lag of thin-walled curved box girder bridges

This note investigates the influence of shear lag for thin-walled curved box girders, including longitudinal warping. The longitudinal warping displacement functions of the flange slabs are approximated by a cubic parabolic curve instead of a quadratic curve of Reissner's method. On the basis of the thin-walled curved bar theory and the potential variational principle, the equations of equilibrium considering the shear lag, bending, and torsion (St. Venant and warping) for a thin-walled curved box girder are established. The closed-form solutions of the equations are derived, and Vlasov's equation is further developed. The obtained formulas are applied to calculate the shear lag effects for curved box girder bridges. Numerical examples are presented to verify the accuracy and applicability of the present method.