= 6.9 — Acceptability of finite element analysis

== 6.9.1 Finite element analysis to determine load effects shall be permitted.

== 6.9.2 The finite element model shall be appropriate for its intended purpose.

= R6.9 — Acceptability of finite element analysis

== R6.9.1 This section was introduced in the 2014 Code to explicitly recognize a widely used analysis method.

== R6.9.2 The licensed design professional should ensure that an appropriate analysis model is used for the particular problem of interest. This includes selection of computer software program, element type, model mesh, and other modeling assumptions.
 A large variety of finite element analysis computer software programs are available, including those that perform static, dynamic, elastic, and inelastic analyses.
 The element types used should be capable of determining the response required. Finite element models may have beam-column elements that model structural framing members, such as beams and columns, along with plane stress elements; plate elements; and shell elements, brick elements, or both, that are used to model the floor slabs, mat foundations, diaphragms, walls, and connections. The model mesh size selected should be capable of determining the structural response in sufficient detail. The use of any set of reasonable assumptions for member stiffness is allowed.
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86 ACI 318-19: BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE
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== 6.9.3 For inelastic analysis, a separate analysis shall be performed for each factored load combination.

== R6.9.3 For an inelastic finite element analysis, the rules of linear superposition do not apply. To determine the ultimate member inelastic response, for example, it is not correct to analyze for service loads and subsequently combine the results linearly using load factors. A separate inelastic analysis should be performed for each factored load combination.

== 6.9.4 The licensed design professional shall confirm that the results are appropriate for the purposes of the analysis.

== 6.9.5 The cross-sectional dimensions of each member used in an analysis shall be within 10 percent of the specified member dimensions in construction documents or the analysis shall be repeated.

== 6.9.6 Redistribution of moments calculated by an inelastic analysis shall not be permitted.
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