How are the hydrostatic loads calculated in Bladed?
The hydrostatic forces are calculated individually for each member, and are made up as a combination of point forces and distributed forces. The hydrostatic forces are split down into three parts, which together account for buoyancy:
1. The hydrostatic pressure force on each end of the member (area x density x g x water depth), applied as point loads on the end of the element.
2. The pressure force acting perpendicular to the member, applied as a linearly varying distributed load. This is a pressure integral in a circle around the member axis. This will be zero if the member is vertical.
3. The pressure force acting parallel to the member, applied as a linearly varying distributed load. This will be zero if the member has no tapering.
If a member crosses through the sea surface then the distance along the member that the surface passes through the member is calculated. The surface is assumed to be perpendicular to the member axis and then the distributed forces are split up between the underwater section and above water section.
For underground members, the seabed is assumed to be saturated, which means that the same hydrostatic loading is applied as underwater.
For more details of the hydrostatic calculation, follow this link and look in the "Engineering Documentation" category.