(4) Section D, Structural Assemblies. This section deals with structural assemblies.
This section includes discussions on built-up sections, mixed systems, lateral bracing, wall stud
systems, and floor, roof or wall steel diaphragm construction.
(5) Section E, Connections and Joints. This section covers the design of
connections and joints, and includes welded connections, bolted connections, screw connections,
shear rupture, and connection to other materials. The provisions for screw connections is new
with this edition.
(6) Section F, Test for Special Cases. This section discusses testing methods and
procedures for the conditions not specifically covered in the specification. This would include
such tests for determining structural performance, confirming structural performance, and
determining mechanical performance. Design guidance for shear walls will be performed in
accordance with chapter 3 of this manual.
c. Wall Studs and Roof Trusses. Wall stud and roof framing sections are typically made
from C shaped sections. These wall stud sections should always have a stiffening lip to aid in the
development of the flange flat width
Table 2-2. AISI Approved Steels (Section A3.1)
Steels that are allowed and are not shown must comply with the ductility requirements of Sections
A3.2 and A3.3. The typically provided by the manufacturer is Other Steel in the AISI Specification
and requires the use of material coupons to verify material properties.
Fy =228 to 345 Mpa
Fu = 310 to 483 MPa
Grades 33, 37, 40, 50
(33 to 50 ksi)
(45 to 70 ksi)
Fy = 552 MPa
Fu = 565 MPa
Grade 80 (Deck and Panels)
Fy =228 to 345 MPa
Fu = 310 to 427 MPa
(33 to 50 ksi)
(45 to 62 ksi)
d. Effective Width. The major cold-formed steel design concept is the "Effective Design
Width" of flat elements. These flat elements can be stiffened, partially stiffened, or unstiffened.
Using a bent edge that can form a lip as on a C or Z section stiffens flat elements. Also, using an
intermediate crease in the middle of the flat element on the top of a hat section, or using another
flat element such as the sides of a hat section. When the stiffening element is not fully effective
such as an overly long lip on a C or Z section the flat element is partially stiffened. An unstiffened
element would be a C or Z section that does not have an edge lip. Cold-formed steel sections
have very high width to thickness ratios which means elements within the section are susceptible
to local buckling. Therefore, only that portion of the section that is capable of taking load is
included in the effective width of the flat element. Currently, only the AISI approach to determine
effective section properties is allowed, other methods that have been used include finite strip
analysis and finite element methods.
e. Advantages of Cold-Formed Steel. The advantages of cold-formed steel systems occur
because of several unique material characteristics such as: the recyclable nature of the material,
low weight, high strength, custom shapes, rounded corners with no fillets, post buckling strength,
and element stiffening characteristics.
f. Limit States. Designers should recognize the two limit states used in the AISI
specification: the Ultimate Limit State (ULS) and the Serviceability Limit State (SLS). The first
limit state is a function of strength, the second is structural function. AISI has very limited
coverage of serviceability limit states since they are different for each owner, user, and designer,
see Paragraph 4.j. for further guidance on live load deflection limits. Typical design
considerations for a member in bending would show how these two limit states are used. The
strength limit states for beams would include: flexure, shear, web crippling, and shear lag, while