Figure 9: Shear forces and bending moments in the side walls from a homogeneous load
The homogeneous loading of a container produces shear forces and bending moments in the side walls of a container as shown in Figure 9. The maximum bending moment from the load P can be calculated as:
This expression serves as limiting value for inhomogeneous loads, which may appear when loading steel coils.
If a coil of the mass mC is placed on longitudinal beams of the length t in the container (Figure 10), a bending moment results at half the length of the container of:
Figure 10: Uniform load of length t longitudinally in a container
This bending moment must not exceed the limiting value presented by equation (4). The mass mC must therefore be restricted to:
This load case applies to usual bedding arrangements for coils of weight classes H and XH.
If two coils of the same mass are placed longitudinally into a container as shown in Figure 11, the full payload of the container may only be utilised, if the coils are not stowed closer to each other than at ¼ and ¾ of the container length, so that the distance t is at least 2.93 m. For a distance less than 2.93 m, the mass of both coils has to be reduced to:
Figure 11: Separated load longitudinally in a container
If three coils of the same mass are placed longitudinally into a container, they have to be stowed at 1/7, 1/2 and 6/7 of the container length for utilising the full payload of the container. That means the centres of the end coils have a distance to the end walls of only 84 cm.
If four coils of the same mass are placed longitudinally into a container, they have to be stowed at 1/8, 3/8, 5/8 and 7/8 of the container length for utilising the full payload of the container. That means the centres of the end coils have a distance to the end walls of only 73 cm.