Average live load is taken as 75 percent of the fully loaded container.
One load cycle is defined as: hoisting the container from the pier, traveling the
trolley and setting the container on the main deck of the ship, hoisting the empty
spreader and traveling the trolley to the pier, and setting the spreader on a
container. Alternatively, the reverse sequence may be used. For container
terminals with no pier storage areas, trolley travel range is taken as 75 percent
of the maximum outreach (measured from the waterside rail) to centerline of the
gantry. For container terminals with pier storage of containers, trolley travel
range is taken as 75 percent of the maximum outreach (measured as above) to 75
percent of the maximum backreach (measured from the land side rail). Secondary
effects due to elastic deformation of the structure must be considered in this
analysis. The maximum stress ranges are limited to 100 percent of AISC allowable
values for Loading Condition 4 (that is, over 2,000,000 cycles).
8) For lateral deflection perpendicular to the boom: gantry lateral
load. The lateral deflection perpendicular to the boom is limited to h/240, where
h is the vertical distance from the rail to the connections between the main
girders and the transverse girders.
9) For lateral deflection parallel to the boom: 300 percent of
trolley lateral load. The lateral deflection parallel to the boom is limited to
h/1400, where h is the vertical distance from the rail to the connections between
the main girders and the transverse girders.
b) Entire Structure (Stowed Configuration). In this configuration, the
boom is secured in its raised position, and the trolley is locked in its stowed
location. Two load cases are considered:
1) Dead load, trolley dead load, lift system, and non-operating
wind load. The wind load is applied in the most adverse direction. The maximum
stresses are limited to 126 percent of AISC allowable values.
2) Dead load, trolley dead load, lift system, and seismic load.
The maximum stresses are limited to 126 percent of AISC allowable values.
Other Structural Assemblies and Components. The machinery house,
diesel engine-generator enclosure, operator's cab, boom control station, stairs,
walkways, platforms, and ladders are to be designed according to the criteria for
similar assemblies and components of portal cranes, as described above in
paragraph 18.104.22.168 and sub-paragraphs.
Mobile Cranes. Structural design criteria for mobile cranes are
prescribed by Society of Automotive Engineers (SAE) standards and are observed by
commercial firms that manufacture such cranes. They include analytical methods
and non-destructive testing of the entire load-supporting structure of the crane
under static conditions. The following SAE standards apply:
J1093; Latticed Crane Boom Systems Analytical Procedure. Booms
ratings developed according to this procedure must be verified by testing
described in J987.