Allowance for the shear when calculating shipboard beams bearing intensive localy distributed loads
In the process of operation, shipboard beams are subjected to the impact of various types of loads, the greatest danger being intense local distributed loads which are the main cause of damage to ship hulls. Therefore, designing ship hulls with minimum weight characteristics, as well as choosing the optimum sizes of connections when reinforcing the beams, require to use methods for calculating hull structures under the action of local loads beyond the elastic limit. The paper presents design models that allow taking into account shear effects in the beam walls, as well as the effect of the support forces on elastic-plastic base on their deformation. These problems can be avoided, if the sector of the frame on which shearing force has reached the limit value can be replaced by an ideal cable lying on the elastic-plastic base with variable stiffness characteristics. The results of the calculation of the shipboard beams have been compared using the described approach and the method of "instantaneous variation of bending parameters". It is shown that for large deflections the discrepancy is insignificant, which is explained by the dominant influence of the support forces on the side skin and longitudinal forces on the behavior of locally loaded frames. The proposed technique allows taking into account the impact of shear effects on deformation of locally loaded frames, which can be used in design and modernization of ship hulls to select the optimum sizes of connections.