Effect of multiple longitudinal stiffeners on ultimate strength of steel plate girders

In the present paper, the effect of multiple longitudinal web stiffeners (up to four) located at their optimum location on the ultimate strength of steel plate girders subjected to predominant shear loading, and combined bending and shear loading is investigated by using nonlinear inelastic analysis. Three dimensional (3D) finite element (FE) models of the steel plate girder are developed and analyzed by using ABAQUS commercial software. The accuracy of the FE models is validated by comparing their results with analogous experimental data. An extensive parametric analysis has been carried out to estimate the influence of specific geometric parameters on the ultimate strength. It has been shown that the shear resistance obtained from AASHTO LRFD equation is conservative since the influence of the longitudinal stiffeners was not considered in computing the shear resistance of the web plate girders under predominant shear loading and combined bending and shear. In addition, it has been demonstrated that the variation of the ultimate strength of the girder is almost monotonic against the various dimensionless geometric parameters, enabling thus the design of girder beams based on interpolation of tabulated data. Finally the results indicate that by adding not more than four stiffeners at the web of a steel plate girder subject either to predominant shear or combined shear and bending loads, an increase in its ultimate strength between 8% and 105% can be achieved.