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Girders
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Joist Girders are open web steel trusses used
as primary framing members. They are
designed as simple spans supporting equally spaced
concentrated loads of a floor or roof system. These
concentrated loads are considered to act at the panel
points of the Joist Girders.
These members have been standardized in the
Weight Table for depths from 20 inches (508 mm) to
72 inches (1829 mm), and spans to 60 feet (18288
mm). Standardized camber is provided as listed in
paragraph 1003.6 of the specifications. Joist Girders
are furnished with underslung ends and lower chord
extensions. The standard depth at the bearing ends
has been established at 6 inches (152 mm) for Joist
Girders weighing less than 60 pounds per lineal foot
(89 kg/m), and 7 1 /2 inches (191 mm) for Joist Girders
weighing 60 pounds per lineal foot (89 kg/m) or more.
Joist Girders are usually attached to the columns by
bolting with two 3 /4 inch (19 mm) bolts. A loose connection
of the lower chord to the column or other support
is recommended during erection in order to stabilize
the lower chord laterally and to help brace the Joist
Girder against possible overturning.
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1003.6 CAMBER
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Joist Girders shall have approximate cambers in accordance
with the following:
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Top Chord Length
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Approximate Camber
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20'-0" (6096 mm)
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1 /4 " 1(6 mm)
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30'-0" (9144 mm)
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3 /8 " (10 mm)
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40'-0" (12192 mm)
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5 /8 " (16 mm)
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50'-0" (15240 mm)
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1" (25 mm)
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60'-0" (18288 mm)
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1 1 /2 " (38 mm)
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