An algorithm for shear stress evaluation in ship hull girders

The Common Structural Rules for Oil Tankers (OT) and Bulk carriers (BC) of IACS mandate the computation of shear flow in hull girders. Such computation involves determinate as well as indeterminate shear flow evaluation due to the multi-celled nature of the OT and BC transverse sections. This necessitates formulation of an algorithm for automatic detection of closed cells within a ship section as well as for automatic determination of positions of virtual slits for computation of indeterminate shear flows. It is also common practice to neglect the effect of longitudinal stiffeners when evaluating the shear flow in cross sections or to consider such effect using a gross approach. In the current work, the computation of shear flow in practical ship transverse sections has been performed. For this purpose an algorithm and subsequent program was developed to automate shear flow calculations which is applicable to any ship type. The results of the program were validated against benchmark examples as well as finite element results. Case studies were performed on VLCC and BC midship sections. The results also prove that consideration of longitudinal stiffeners does not significantly affect the magnitude of the shear stresses developed in the ship plating.