A semi-discrete method for shear lag analysis of thin-walled members

A semi-discrete displacement variational method is proposed to analyze the thin-walled members. In this method, the longitudinal displacement w is expressed by [ϕ(s)] (w(z)}, in which ϕ (s), representing the displacement distribution along the cross section, is expressed by an assumed interpolation function, while w(z), representing the longitudinal distribution of w, can be obtained analytically by the variational principle. The method taking into account the middle surface shear strains, can be used in tall building and bridge analysis to show the ‘shear lag’ effect. It can much reduce the computation time in comparing with the finite element method or even the finite strip method, so that it is particularly useful in practical design especially at its preliminary stage.