MIL-HDBK-1038
The skewing forces are applied to the wheel flanges (perpendicular to the
rails). The forces due to gantry travel must be at least 5 percent of the total
crane weight, including the container weight, and are applied in the direction of
gantry travel; additionally, 25 percent of that force is applied perpendicular to
the direction of travel. The maximum stresses are limited to 90 percent of the
AISC allowable value.
2) Dead load, trolley dead load with a 10 percent vertical impact
factor, live load plus lift system with a 30 percent vertical impact factor,
trolley lateral load, and a 55 mph operating wind applied in the most adverse
direction.
The trolley lateral load due to its acceleration/deceleration on the boom
and main beams is calculated on the basis of the trolley drive motor and brake
characteristics but must be at least 10 percent of the trolley dead load, live
load, and lift system; additionally, 25 percent of that force is applied
perpendicular to the direction of travel. The maximum stresses are limited to 90
percent of AISC allowable values.
3) If the crane is equipped with a load beam: dead load, trolley
dead load, load beam rated load plus load beam lift system with a 30 percent
vertical impact factor, and operating wind load. The rated load is assumed to be
at the geometric center of the load beam. The maximum stresses are limited to 90
percent of AISC allowable values.
4) Dead load, trolley dead load, lift system (head block, spreader,
wire ropes, and sheaves), snag force, and operating wind load.
Snag force is due to the full impact of the headblock and empty spreader
moving at maximum hoist speed and becoming snagged in the ship's cell guide or
structure, or two-blocking against the trolley. The mitigating effect of the
reeving system anti-snag system is considered in determining the snag force. The
maximum stresses are limited to 135 percent of AISC allowable values.
5) Dead load, trolley dead load, live load, lift system, operating
wind load, and collision force.
Collision force is due to the full impact of the crane hitting its end
stops or the bumpers of another crane, or of the trolley hitting its end stops, at
rated speed but with the power off. The energy absorbing or deceleration
characteristics of the bumpers are considered in determining the collision force.
The maximum stresses are limited to 135 percent of AISC allowable values.
6) Dead load, trolley dead load, live load, lift system, and
seismic load. The maximum stresses are limited to 135 percent of AISC allowable
values.
7) For fatigue analyses: dead load, trolley dead load, lift system,
average live load, and trolley lateral load. The stress range is defined as the
algebraic difference between the maximum and minimum stress at a point during one
load cycle.
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