Parametric studies of uniaxially compressed and laterally loaded stiffened plates for minimum cost

摘要

The elastic secondary deflection due to compression and lateral pressure is calculated using the Paik's solution (Paik et al. 1991) of the differential equation for orthotropic plates, and the self-weight is also taken into account. Besides this deflection some more deformations are caused by lateral pressure and the shrinkage of longitudinal welds. The stress constraint includes several effects as follows: the average compression stress and the stress caused by compression, lateral pressure and the shrinkage of longitudinal welds. The constraint on local buckling of the base plate strips is also included considering the effect of initial imperfections and residual welding stresses with formulae proposed by Mikami and Niwa (Mikami I., Niwa K. 1996). The unknowns are the thickness of the base plate as well as the dimensions and number of stiffeners. The optimum dimensions and number of stiffeners are determined by a mathematical programming method. The cost function to be minimized includes material and welding costs. The results show that the trapezoidal stiffener is the most economic one. The cost saving can be 69 % comparing with various ribs.