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 where,
[beta] = constant depending on the support conditions as follows:
for simply-supported element = 0.0130
for simple-fixed or continuous element = 0.0062
I = moment of inertia of the element.
(b) The extent of plastic behavior is expressed in terms of a
ductility ratio:
EQUATION:
[mu] = Xm/XE
(101)
The following ductility ratios are recommended:
[mu] = 3.0 for reusable elements
[mu] = 6.0 for non-reusable elements.
In order to restrict the magnitude of rotation at the supports, limitations
are placed on the maximum deflections, namely:
Xm = L/57 or [theta]max = 2[deg.] for reusable elements
Xm = L/29 or [theta]max = 4[deg.] for non-reusable elements
(c) For a one degree-of-freedom analysis of a panel's
behavior, the properties of the equivalent system can be evaluated by using
a load-mass factor, KLM = 0.74, which is an average value applicable to
all support conditions. The natural period of vibration for the equivalent
single-degree system is thus obtained by:
EQUATION:
TN = 2[pi](0. 74m/KE)1/2
(102)
where,
m = w/g is the unit mass of the panel and
KE = ru/XE is the equivalent elastic stiffness of the system.
(d) The problem of rebound should be considered in the design
of decking due to the different section properties of the panel, depending
on whether the section on the flat sheet is in compression. Figure 41 shows
the maximum elastic resistance in rebound as a function of T/TN.
(2) Resistance in Shear. The shear capacity of the web of a
cold-formed panel is dictated by instability due to either simple shear
stresses or combined bending and shearing stresses.
2.08-138
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