Shear lag analysis of beam-columns

This paper presents a new systematic approach to the shear lag analysis of structures that are subjected to simultaneous bending and axial forces. The shear lag effects in beam action and column action are considered separately in analogy to the stress calculation of beam-columns, using box girder as an illustrating example. Based on the principle of minimum potential energy, the governing differential equations for shear lag are derived. Closed-form solutions of the combined shear lag effects are obtained by solving the two sets of differential equations under specified boundary conditions. The results are verified by tests of Perspex models of girders and numerical simulation using the finite strip method. The analysis can readily include cross-sections other than box girders.