15 August 2002
Shiploads. Determine shiploads on the floor for the specific class ship.
Figures 5-1 and 5-2 indicate shiploads that have been used for four basic types of
ships. Note the extra heavy loads at the stern overhangs. Nuclear powered ships have
extra heavy loads under the reactor.
Thin Floors. For thin floors, investigate the effect of these extra heavy
loads, and reinforce the floor locally as necessary.
Positioning. Base the blocking arrangement for design of the floor on
any likely positioning of ships in the dock. Larger ships may be docked only on the
centerline of the graving dock. For docks wide enough to permit multiple docking of
ships abreast, or long enough to permit various placement fore and aft, apply the load
pattern for such smaller ships multiple docked in odd positions to the floor as well as the
load pattern of larger ships docked on the centerline.
Wheel Loads. The typical wheel loadings for a 36287 kg (40-ton)
locomotive crane, and 22680 kg (25-ton), 31750 kg (35-ton), and 45359 kg (50-ton)
portal cranes are given in MIL-HDBK-1025/1 Piers and Wharves.
Full Hydrostatic Graving Docks. Crane wheel loads do not normally
influence the design of the main wall of graving docks designed to resist full hydrostatic
pressure, because of the extensive longitudinal distribution of the wheel loads by the
walls. Wheel loads from cranes operating around full hydrostatic graving docks,
therefore, usually are significant only in the design of local beam supports under rails
crossing the overhead of service tunnels, pumpwells, and other auxiliary structures.
Relieved and Partially Relieved Graving Docks. For relieved and
partially relieved graving docks, crane wheel load may influence the design of main
dock walls as well as the design of local beam supports.
Mobile Crane Loads. Mobile cranes are to some extent replacing
locomotive cranes. Use truck crane wheel loads as given in MIL-HDBK-1025/1 Piers
and Wharves or the crane manufacturers wheel load specifications (covering many of
the larger ~ 220-Ton mobile cranes used by PWCs/Shipyards/Private Contractors) for
beams, slabs, and the overhead structure of the pumpwell, where crane track loading
does not govern.