UFC 4-023-03
25 January 2005
3-2.8
Linear Static Analysis Procedure.
Perform the following steps in a Linear Static Analysis. Note that a second
order or P-∆ analysis is required.
1. For AP analyses for load-bearing elements that do not have adequate vertical tie
force capacity, remove the element from the structural model in accordance with
the material-specific requirements given in Chapters 4 to 8 (see Section 3-2.3.1).
For AP analyses of MLOP and HLOP structures, remove the column or load-
bearing wall per Sections 3-2.3.2 and 3-2.3.3.
2. Apply the loads defined in Section 3-2.4.2.
3. After the analysis is performed, compare the predicted element and connection
forces and deformations against the acceptability criteria that are shown
generically in Table 3-1. To demonstrate compliance with the acceptability
criteria, a software package with modules that perform building code checks may
be used, providing the modules can be tailored to check the criteria in Table 3-1.
Confirm that all material-specific code provisions for bracing, compactness,
flexural-axial interaction, etc, are met.
4. If none of the structural elements or connections violates the acceptability
criteria, the analysis is complete and satisfactory resistance to progressive
collapse has been demonstrated. If any of the structural elements or
connections violate the acceptability criteria, perform the following procedure:
A. Modify the geometry or material properties of the model, per Table 3-1
(i.e., remove elements and/or insert hinges and constant moments).
B. If an element was shown to fail, redistribute the element's loads per
Section 3-2.4.3.
C. Re-analyze this modified model and applied loading, starting from the
unloaded/undeformed condition.
D. At the end of the re-analysis, assess the resulting damaged state and
compare with the damage limits in Section 3-2.6. If the damage limits are
violated, re-design and re-analyze the structure, starting with Step 1. If
the damage limits are not violated, compare the resulting internal forces
and deformation of each element and connection with the acceptability
criteria
E. If any of the acceptability criteria are violated in the new analysis, repeat
this process (Steps A through E), until the damage limits are violated or
there are no more violations of the acceptability criteria. If the damage
limits are violated, re-design and reanalyze the structure, starting with
Step 1. If the damage limits are not violated and no new elements failed
the acceptability criteria, then the design is adequate.
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