FAQ OF THE MONTHNOVEMBER 2024 QUESTION:
ANSWER: 
The effective strip method assumed continuous sheathing. If the sheets are lapped, the same reduction factor can reasonably be applied.
QUESTION: Just for my clarity as the verbiage change in S400-20 is not as direct as S400-15. The below verbiage just seems to be removed from each assembly section. Would the following still apply for shear walls and strap braced walls in S400-20? Cold Formed walls w/ Wood Sheathing (from S400-15):
Strap Braced Walls (from S400-15):
Also do you know of any published design examples following the steps of S400-20? ANSWER:
Although, not based on AISI S400-20, AISI D113-19, Cold-Formed Steel Shear Wall Design Guide, illustrates the design procedure for the consideration of expected strength and overstrength. Determination of the overstrength factor, ΩE, is updated in S400-20, but application of the factor is as illustrated in D113-19. Information regarding AISI D113-19 can be found at https://buildsteel.org/technical/codes-and-standards/aisi-releases-cold-formed-steel-shear-wall-design-guide-2019-edition/
QUESTION: AISI S240-20 Section B5.2.1.2 (b) states:"(b) For a Type II shear wall, the nominal strength [resistance] for shear, Vn, is based upon a screw spacing of not less than 4 inches (100mm) on center." Does this imply that 4" is the minimum screw spacing at the sheathing panel edges and the respective capacities are limited to 4" spacing, i.e. 2" and 3" spacings shown in tables B5.2.2.3-1 and B5.2.2.3-2 cannot be used. ANSWER:
QUESTION: AISI S220, North American Standard for Cold-Formed Steel Nonstructural Framing, Section A1.2.1 has the following limitations:
I am struggling with limit No. 2. For example, doesn’t a 100 lb/ft of superimposed axial load, exclusive of sheathing material, negate limitation No. 3?
The key to Section A1.2.1 limitations is that all the limitations must be met for a member to be considered nonstructural. Also, limitations 1 and 2 apply to systems, i.e., members in a wall system, whereas limitation 3 applies to each member only. So, it would be okay to support a piece of equipment that is 300 lbs if the load is distributed over the length of the wall and no individual member was assigned to support more than 200 lbs. Limit 2 applies most often when interior partitions are supporting ceilings or floors from above. This discourages closely spaced nonstructural members used to support mezzanine floors.
QUESTION: Hello - I was curious if you were aware of a typical detail you could point me to as a starting point for typical penetrations through plywood sheathed light frame stud shear walls. I work as a structural engineer, and we are trying to specify the appropriate detailing for new duct penetrations through a new shear wall. The duct penetrations are roughly 30"x30” but vary in size across the building. Any assistance would be greatly appreciated.
There is no document that specifically addresses force transfer around openings for cold-formed steel framing. However, the APA Technical Note T555A “Design of Force Transfer Around Openings (FTAO)” summarizes the design concept and technical issues regarding force transfer around openings. The document is a download from https://www.apawood.org/ftao.
QUESTION: Currently, I am involved in design cold-formed steel framing. Honestly, I am facing the difficulty to locate information to gain an understanding the cold-formed steel framing design. While in school I didn’t study any material related to cold-formed steel design. In the school syllabus, they focused more on concrete structures and hot-rolled steel structures. I am trying to find material for cold-formed steel design, but there is not much to find. Therefore, I emailed you to get more information about cold-formed steel framing. My question is: Could you be please guide me with some recommendations and references (book, class note, online sources, training etc.) on how I can improve my skills on cold-formed steel framing design to build a strong background on the subject?
There are several educational opportunities available.
QUESTION: I am working on a large senior housing project which is required to have 2-hour protection of all structural components: bearing walls, columns and floor-ceiling assemblies. I would like to confirm the requirements for meeting this 2-hour rating (particularly for the walls), preferably in the form of UL listings. The structure is assumed to be bearing walls at corridors and exterior walls. Typical floor-ceiling assembly of upper floors and roof are to be 18" deep trusses. The other specific aspect I would like to confirm, is if there is any height limitation to meeting the 2-hour rating requirement as the ground floor has a 16'-0" floor-to-floor height.
You may find the following two documents helpful:
There are multiple 2-hour assemblies for both load-bearing and non-load bearing cold-formed steel framed walls, and structural floor-ceiling and roof-ceiling assemblies. For these assembles, there are no height limitations other than the structural capacities of the members themselves. So as long as structural analysis shows that the members can span your project’s 16’ height and they meet the UL design requirements, then there is no additional height limitation requirement from the fire rating.
QUESTION: Does AISI D114, Clip Angle Design Guide, require consideration of prying action when evaluating the anchored leg of a clip angle?
Traditional limit states associated with prying action are:
However, based on the University of North Texas study on thin screw attached clips two additional strength limit states were identified and are addressed in AISI D114:
The pull-over strength limit state, Pnov is defined as,
The pull-over strength design equation was calibrated to test results. Thus, any prying effects are included in the design equation. Therefore, prying effects need not be considered. But for the pull-out strength and screw tension strength evaluations, the prying effects should be considered. The D114 deflection limit state is as follows:
Based on the UNT testing, for thicker clip angles, the 1/8” deflection limit was achieved prior to a failure of the clip angle. Thus, when applying the AISI D114 design methods because a deflection limit is imposed for clip angles thicker than 54 mils the traditional prying action limit states are not a design consideration. However, if the 1/8” deflection limit is not imposed as a design limit state, then prying action should be considered when evaluating the following limit states:
QUESTION: Why does AISI D114-21, Cold-Formed Steel Clip Angle Design Guide, not consider the bending limit state?
When subjected to a shear load (Figure 1), a clip angle is structurally analogous to a short cantilever beam. Based on research at the University of North Texas, the typical clip angle failure occurs in a panel of length L by depth B (Figures 2 and 3). Thus, the aspect ratio for the failure panel is defined as L/B. A beam is generally regarded as a “deep beam” when its shear span-to-depth ratio, L/B, is < 2.0. Because a clip angle may typically have an L/B ratio equal to or less than 2.0 they exhibit behavior consistent with a deep beam. Also, as defined by AISI D114, the equations are limited to clips having L/B < 1.4.
The main difference between a shallow beam (typical floor joist or curtain wall stud) and a deep beam is that in the case of a shallow beam shear deformations are negligible and could be ignored while shear deformations must be considered in the analysis and design of a deep beam. Because of the geometry of deep beams, their behavior is different from shallow beams. Deep beams are shear dominant and shallow beams are flexure dominant. Thus, the clip angle predominantly fails in shear rather than flexure because it has a small L/B ratio. FEBRUARY 2024
JANUARY 2024
ASTM A1003 was developed to be inclusive of the former ASTM A653, A792 and A875 standards, provide additional options for suppliers, and be consistent with the material requirements of the AISI S240, North American Standard for Cold-Formed Steel Structural Framing. The AISI S240 Section A3.1 User Note states: “ASTM A1003 was developed to be inclusive of ASTM A653/A653M, A792/A492M, A875/A875M and A1063/A1063M standards. For more information see CFSEI Tech Note G801. Therefore, products furnished to these material standards meet the requirements of A1003/A1003M.” DECEMBER 2023
However, In the United States and Mexico, for foundations, the required strength shall be determined from the seismic load effect and need not include the overstrength factor (Ωo) nor consider the expected strength of the seismic force-resisting system unless otherwise specified in the applicable building code. The following User Note has been adopted for the next edition of AISI S400: “In the United States and Mexico, the design of the foundation itself need not consider overstrength or expected strength. However, hold-downs and anchorage into the foundation are capacity protected components. Design of these components, including limit states associated with failure of the foundation material (e.g. concrete breakout, side face blowout, anchor pullout and pryout) must meet the required strength provisions of Section B3.” A similar user note has not been adopted for the next edition of AISI S240 because S240 is limited to design for an R value of 3. NOVEMBER 2023
In AISI S400:
S240 and S400 do not have a requirement. However, good practice would recommend staggering joints no matter what orientation of the panels. OCTOBER 2023
SEPTEMBER 2023
AUGUST 2023
JULY 2023
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To eliminate the repetitive listing of the various elements that require consideration of expected strength or overstrength, AISI S400-20 defined “capacity protected components”. Section B3 provides the design requirements for these components. Each SFRS has its own list of capacity protected components. For example, for wood structural panel shear walls, Section E1.4.1.2 lists the capacity protected components. The Commentary for Section E1.4.1.2 also discusses “Capacity Protected Components”.
Splicing of a strap is not prohibited in either AISI S240, 
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