UFC 4-023-03
25 January 2005
Table 8-2 Acceptability Criteria and Subsequent Action for Cold-Formed Steel
Subsequent Action for AP
Structural Behavior
Acceptability Criteria
Model
Φ MnA
Element Flexure
Section 8-3.1.1
AISI/COS/NASPEC
Element Combined Axial
2001 Chapter C5
Section 8-3.1.2
and Bending
Interaction Equations
Φ VnA
Element Shear
Section 8-3.1.3
Connection Design
Connections
Section 8-3.1.4
StrengthA
Deformation Limits,
Deformation
Section 8-3.2
defined in Table 8-3
A
Nominal strengths are calculated with the appropriate material properties and over-
strength factor Ω; all Φ factors are defined per AISI/COS/NASPEC 2001.
8-3.1.1
Flexural Resistance of Cold-Formed Steel.
For cold-formed steel, the flexural design strength is equal to the nominal
flexural strength, multiplied by the strength reduction factor Φ; calculate the nominal
flexural strength per AISI/COS/NASPEC 2001 procedures.
For Linear Static Analysis, if the required moment exceeds the flexural design
strength and if the geometry and supports of the cold-formed steel member are
sufficient for a plastic hinge to form and undergo significant rotation, add an equivalent
plastic hinge to the model, by inserting a discrete hinge at the correct location within the
member. For a connection with a plastic hinge, insert the hinge at the offset from the
member end; use engineering analysis and judgment to determine the offset length.
Also, apply two constant moments, one at each side of the new hinge, in the
appropriate direction for the acting moment; see Figure 3-9. For Nonlinear Static and
Dynamic Analysis, use software capable of representing post-peak flexural behavior.
Ensure that shear failure will not occur prior to developing the full flexural design
strength.
If the structural element is not able to develop a constant moment while
undergoing continued deformations, remove the element when the internal moment
exceeds the flexural design strength. Redistribute the loads associated with the
element per Section 3-2.4.3.
8-6
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