Structural design of stiffened plates of industrial duct walls with relatively long panels undergoing large deformations

Structural design of stiffened plates of the walls of rectangular-sectioned industrial ducts is currently based on the strip method that follows the linear flexural beam theory. The current design method assumes that the displacements generated in the plate are small and the membrane forces that generate in the plate are negligible. This paper addresses the current design method and discrepancies associated with it to present a new design approach that takes into account the effects of large displacements on the load-deformation and load-stress behavior of stiffened plates. Two different sets of formulas are presented based on Finite Element analysis of rectangular plates with relatively long aspect ratios that estimate the maximum stress and deformation in the typical and edge panels of stiffened plates. These formulas are then used to establish design equations for stiffened plates. Based on the findings of this paper, a reduction of 30-40% in the plate thickness could be achieved if the new design approach is selected over the conventional design method.