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 b.
Design of Cold-Formed, Light-Gage Steel Panels Subjected to
Pressure-Time Loading.
Problem:
Design a roof deck as a flexural member which responds to
pressure-time transverse loading.
Given:
(1) Pressure-time loading.
(2) Design criteria ([theta]max and [mu]max for either
reusable or non-reusable cold-formed panel).
(3) Span length and support conditions.
(4) Mechanical properties of steel.
Solution:
(1) Determine an equivalent uniformly distributed static load
for a 1-ft width of panel, using the following preliminary
dynamic load factors:
1.65 reusable
DLF =
1.40 non-reusable
These load factors are based on an average value of T/TN
= 10.0 and the design ductility ratios recommended in
Equation (101). They are derived using Figure 6-7 of
NAVFAC P-397.
Equivalent static load:
w = DLF x p x b
b = 1 ft.
(2) Using the equivalent load derived in Step 1, determine the
ultimate moment capacity (assume positive and negative are
the same).
(3) Determine the required section moduli.
Select a panel.
(4) Determine actual section properties of the panel, S+,
S -, I, and m = w/g (for 1-ft width of a panel).
(5) Compute ru, the maximum unit resistance per 1-ft width of
panel, using Equation (98) or (99).
(6) Determine the equivalent elastic stiffness from
KE = ru/XE,
where XE is from Equation (100).
2.08-176
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