FLEXURAL-TORSIONAL-DISTORTIONAL ANALYSIS OF DOUBLE SPINE MONO-SYMMETRIC BOX GIRDER SECTION

Abstract

The differential equations for torsional-distortional analysis of a double spine mono-symmetric box girder section were obtained following Vlasov’s theory. The evaluation of Vlasov’s coefficient of the governing differential equations formed a major part of this work. This involved the valuation of the various strain mode diagrams for the box section and an assessment of the strain mode interaction to ascertain the relevant strain modes that affect torsional and distortional displacements. Vlasov’s coefficients for the governing equations of equilibrium were obtained using Morh’s integral for displacement computations diagram multiplication of the strain modes diagram. By substituting the coefficients into the governing equilibrium equation, a set of coupled fourth order differential equations of equilibrium were obtained. The solution of these equations by method of Fourier sine series gave the flexural torsional and distortional displacements of the 20m simply supported box girder section. The maximum torsional-distortional and flexural displacements were 2.972mm, and 8.773mm respectively. All the strain mode interaction were considered in flexural-torsion-distortional analysis. The maximum torsional-distortional and flexural displacements were 1.448mm, 8.288mm, and 22.186mm respectively.