Intermediate Moment Frames (IMF) per AISC 341-16 §E2

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Last updated: Nov 09, 2023 by oğuzcan hadim
3 min read

How does ideCAD control intermediate moment frame requirements according to AISC 341-16?

Stability Bracing of Beams

Beams should be provided to brace the requirements for moderately ductile members in Section D1.2a. It’s important to design beam braces that are placed near concentrated forces and changes in cross-section. It’s automatically controlled and reported by the program.

 

Members

Basic Requirements

Intermediate moment frames that moderate ductility level are load-bearing systems in which the beams have the ability to perform the shear zone of the beam-column joints to a limited amount of nonlinear deformation under earthquake effects.

Beam and column members should provide the requirements for moderately ductile members according to Table D1.1.

Limiting Width-to-Thickness Ratios for Compression Elements for Moderately Ductile and Highly Ductile Members

Limiting Width-to-Thickness Ratios for Compression Elements for Moderately Ductile and Highly Ductile Members

Description of Element

Width-to- Thickness Ratio

Limiting Width-to-Thickness Ratio

Example

λhd
Highly Ductile Members

λmd
Moderately Ductile Members

Flanges of rolled or built-up I-shaped sections, channels and tees; legs of single angles or double-angle members with separators; outstanding legs of pairs of angles in continuous contact

 

 

 

b/t

 

 

 

 

 

 

 

Flanges of H-pile sections per Section D4

 

b/t

 

not applicable

 

Stems of tees

d/t

Walls of rectangular HSS used as diagonal braces

b/t

Flanges of boxed I-shaped sections

b/t

Side plates of boxed I-shaped sections and walls of built-up box shapes used as diagonal braces

h/t

Flanges of built up box shapes used as link beams

b/t

Webs of rolled or built-up I shaped sections and channels used as diagonal braces

hw/t

 

Where used in beams or columns as flanges in uniform compression due to axial, flexure, or combined axial and flexure:

  1. Walls of rectangular HSS

  2. Flanges and side plates of boxed I-shaped sections, webs and flanges of built-up box shapes

 

 

 

 

 

 

b/t

 

 

h/t

 

 

 

 

 

 

 

 

 

 

 

Where used in beams, columns, or links, as webs in flexure, or combined axial and flexure:

  1. Webs of rolled or built-up I shaped sections or channels [b]

  2. Side plates of boxed I-shaped sections

  3. Webs of built up box sections

 

 

 

 

h/tw

 

 

h/t

 

 

h/t

For Ca ≤ 0.114

For Ca > 0.114

where


For Ca ≤ 0.114

For Ca > 0.114

where


 

Webs of built-up box sections used as EBF links

h/t

 

Webs of H-Pile sections

h/tw

 

not applicable

Walls of round HSS

D/t

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Limiting Width-to-Thickness Ratios for Compression Elements for Moderately Ductile Members per AISC 341-16 with ideCAD

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