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 MIL-HDBK-1038
b)
J987; Rope Supported Lattice-Type Boom Crane Structures Method of
Test. The test is performed on an instrumented crane and approximates the maximum
loading conditions on all its structural components. The maximum allowable
stresses and deflections are specified.
c)
J1078; A Recommended Method of Analytically Determining the
Competence of Hydraulic Telescopic Cantilevered Crane Booms. This standard serves
as a supplement to J1063.
d)
J1063; Cantilevered Boom Crane Structures Method of Test.
This
test is similar in scope and methodology to J987.
5.1.2.8
Gantry and Semi-Gantry Cranes. These cranes, being similar to OET and
underrunning cranes, are designed according to the criteria of CMAA #70 and CMAA
#74, as applicable. Equalized ground-level travel truck frames are designed as
portal crane components, but for the load cases of CMAA #70.
5.1.3
Stability. Since portal, floating, container, and mobile cranes are
subject to overturning, a key design requirement is their margin of stability.
ASME standards prescribe stability criteria for all these crane types. These are
supplemented by additional stability requirements established by the NCC. Gantry
and semi-gantry cranes have a relatively stable configuration, but their minimum
margin of stability should be checked. The following stability requirements apply
to the individual crane types and represent the minimum criteria. Other stability
cases may be added if warranted by local operational conditions. Such additional
cases may include removal of the boom (for maintenance), modification of the boom,
variation of counterweight, or unique lifts.
5.1.3.1
Portal Cranes. The stability requirements defined below apply to
straight-line rated cranes. For variably rated cranes, (cranes with variable hook
capacity/radius ratings at some or all of their operating range), several hook
load/radius combinations, at 5 to 10 foot increments, are to be used, in the
stability cases defined below.
a)
Roller Path Designs. For cranes with the upperworks on a roller
path and king pin assembly, the distance from the center of rotation to the
resultant of all forces in the plane of the roller path must be maintained within
90 percent of the roller path radius for two cases:
1) 130 percent of rated capacity on any hook at maximum operating
radius.
2) No load on the hooks, boom at its minimum operating radius, and
80 mph non-operating wind from the front.
b)
Rotate Bearing Designs. There are no stability requirements for the
upperworks on rotate bearings, provided that the bearing moment-carrying capacity
is not exceeded.
c)
Entire Crane. The entire crane, of either roller path or rotate
bearing design, is required to maintain overall stability for the following four
cases. The resultant of all forces is translated to the plane of the tipping axis
either on the rails or through the main gudgeon pins. When the tipping axis is
the
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