Precision Structural Engineering

Project Types: Light Gauge Steel

Light Gauge/ Cold Formed steel Code

Light Gauge/ Cold Formed steel Code

Light Gauge/ Cold Formed steel Code


1-For simple residential home, the prescriptive method could be used in the International Residential code, IRC.

  Section R603.1 General:

The provisions of this section shall control the construction of exterior steel wall framing and interior load-bearing steel framing for buildings not more than 60 feet long perpendicular to the joists or truss span, not more than 40 feet wide parallel to the joist or truss span, and not more than two stories in height. All exterior walls installed in accordance with the provisions of this section shall be considered as load-bearing walls. Steel walls constructed in accordance with the provision of this section shall be limited to sites subjected to a maximum design wind speed of 110 miles per hour, Exposure A, B, or C and a maximum ground snow load of 70 psf.

2-For members in residential projects where the material presented in the IRC don’t give an answer and for commercial projects, the International Building Code, IBC must be used. The IBC reference the Cold-Formed Steel Design, AISI Manual, by American Iron and Steel Institute.

Light Gauge/ Cold-Formed Steel Standards:

Universal Designation for Light gauge/ Cold-formed Steel:

Light Gauge/ Cold Formed steel Code 


The steel stud Manufacturers Association ( SSMA) has Published  a catalog using a new designator system called  "The right STUF". 

The intent of the new designators is to make steel framing products easier to use and to accelerate their acceptance in new markets.

Light Gauge/ Cold Formed steel Code

The C-shaped is used the most for the structural members such as studs, floor joists, roof rafters, roof trusses etc. The C-shaped section must have stiffeners/ lips with specified length/width to prevent local buckling. Please see the figure below

 

3. SECTION DESIGNATION AND PROPERTIES:

THE Right STUFF:
Universal Designator System for Light Gauge Steel Framing Members
The Right STUFF will identify any common light gauge steel framing member using:

Web Depth (D), expressed in 1/100th inches.
Flange Width (B), expressed in 1/100th inches.
Minimum Base Metal Thickness (T), expressed  in mils (1/1000th inches), and the following  designators,
S= Stud or Joist Sections with Flange Stiffeners (C-Shapes)
T = Track Sections
U = Cold-Rolled Channel or Channel Studs (w/o Flange   
Stiffeners)
F = Furring Channels

Light Gauge/ Cold Formed steel Code

EXAMPLES:

Designation for a 5-1/2"-16 gauge C-shape with 1-5/8" flanges and 1/2" stiffening lip = 550S162-54 

54    Minimum bas metal thickness in mils (.054in = 54 mils) 162  1-5/8" flange in 1/100th inches
S      Stud or joist with flange stiffeners
550             5-1/2" member depth in 1/100th inches (outside to outside
dimension)

 Designation for a 3-1/2"-20 gauge Track with 1-1/4" flanges =
350T125-33

-33    Minimum bas metal thickness in mils (.033in = 33 mils)
125  1-1/4" flange in 1/100th inches
T      Track section
350   3-1/2" member depth in 1/100th inches (inside to Inside  dimension)

Light Gauge/ Cold Formed steel Code

4. FASTENERS AND CONNECTIONS

a.  All fasteners shall be installed according to the manufacturer's  approved product evaluation report [ICBOapproval].
b.  Refer to fastener schedule and shearwall schedule per plan.
c.  Screws
1.  All screws shall be a minimum size of #8 unless otherwise  specified.  All screws shall be corrosion resistant and shall be  spaced such that the minimum center-to-center or edge distance of three screw diameters is maintained. Self in -drilling tapping screws shall conform to SAE-J78.  A minimum of three  exposed  threads shall extend through the supporting steel member. Screws shall penetrate individual components of connections without causing permanent   separation between the components. Screws shall be installed in a manner such that the threads or  holes are not  stripped. Head styles, threads, and point types for screws shall be selected based on application  conditions and manufacturer  recommendations.
2.   Screw Diameter Size Guidelines Based on Total Thickness of Steel.

Light Gauge/ Cold Formed steel Code

For SI:  1" = 25.4 mm.are in
1.  Greater thickness' are possible, consult screw manufacturer.
2.  Self-drilling trapping screws are required when total  thickness of steel exceeds 0.033 inches.
Sharp point screws are acceptable for steel thickness' of 033 inches (0.84 mm) or less.
c- Bolts shall meet or exceed the requirements of ASTM A307.
Bolts  shall be installed with nuts and washers. Center to center spacing of bolt holes, connecting sheet metal material to concrete, shall be a minimum of three bolt diameters. Distance from the center of the  bolt hole to the edge of the connecting member shall not be less than 1-1/2 bolt diameters. Bolt  hole  diameter shall not exceed the bolt diameter by  more than 1/16 inch.
d. Using pneumatically driven pins to attach floor, roof, and walls.
Structural sheathing are allowed, provided:
1. Pin diameter shall be 0.10 inch or more.
2. Pins shall penetrate the steel framing a minimum of 1/4 inch.
3. Minimum distance between pins and panel edges shall be 3/8  inch.
4. Use adhesive between sheathing and floor joists.
5. Submit manufacturers design values for approval to the engineer of  record.

5. COLD FORMED STRUCTURAL FRAMING (LIGHT GAUGE STEEL):
1.  GENERAL
a.  The structural framing and its installation shall meet the following  standards:

2.American Society for Testing and Materials (ASTM) Standard C- 955 - Standard Specification for Load Bearing (Traverse and  Axial) Steel Studs, Runners (Tracks), and Bracing or Bridging for Screw Application 0f Gypsum Board and Metal Plaster Bases.

Load Bearing (Traverse and Axial) Steel Studs and Related  Accessories.
b.  Manufacturer of Light Gauge Framing:
1.  Company specializing in fabrication of structural framing components with five years minimum experience.

      meeting current  Inspection Guidelines.
c.  Temporary bracing shall be provided until permanent  bracing has been installed.
d.  Punchouts, Cutting, Notching, and Hole Stiffening Flanges of joists,  studs, headers, and other structural members shall not be  cut or  notched without an approved design.  Web holes closer than 12  inches from center of hole to joist bearings, shall  be reinforced with  a solid steel plate, stud, joist, or track section of an equivalent  thickness to the member it reinforces,  provided that the following limitations are met:

      exceed half the  depth of the web, and

      4 inches or the depth of the web, whichever is greater. Reinforcement  shall extend at least 1 inch beyond all edges of the hole and shall  be attached to the web   with #8 screws (minimum) spaced no  greater than 1    inch on center along the edges of the  reinforcement.

     members shall not  exceed 1-1/2 inches wide x 4 inches long located along  the centerline of the web at a minimum center to center spacing  of 24 inches.

e.  The framing members shall have ends squarely cut by shearing or  sawing, be installed plumb, square, true to line and  securely fastened  per the contract documents or approved connection details.
f.  Submit shop drawings and product data.  Indicate on shop drawings component details, framed openings,   anchorage, loading, type and location of fasteners and accessories or items required for other related  work.
2. MATERIAL
a.  The cold-formed structural framing and accessories shall be  manufactured from structural quality steel having minimum  yield strength of 33 KSI, for all design thickness' and have  minimum protective coating equal to G-60 galvanized finish  (ASTM A653M-95, Z180). The steel shall conform to one of the following ASTM Standards:  ASTM A653.
b.  Structural framing members shall conform to ASTM C955 and have engineering properties calculated in conformance with the  AISI "Cold Formed Steel Design Manual", latest edition.
c.  Load bearing steel framing members shall have a legible label, stamp, stencil, or embossment, at a minimum of 48 inches on center, with the following information as a minimum:
1.  The manufacturer's identification.
2.  The minimum uncoated steel thickness.
3,  Minimum yield strength in kips per square inch.
4.  "ST" for structural members.
5.  Metallic coating weight (mass).
3. WALL FRAMING
a.  Building paper and sealer, or equivalent, shall be provided between  the underside of the tracks when fastened directly to concrete.
b.  All load bearing studs shall be aligned with trusses, joists, and other horizontal or vertical load carrying members above or  below the wall stud.  Top and bottom wall tracks shall be of equal or greater thickness than that of the studs.
c.  Studs shall have full bearing against inside track web (1/16 inches  max. gap), prior to stud and track attachment.
d.  Load bearing steel studs shall be laterally braced. Refer to 1/S2 for construction details.

     plywood)  fastened to wall studs in accordance with fastener schedule and shear wall schedule shown on plans. Sheathing shall cover the full-height of the wall from   the  bottom track to  the top track. All  edges and interior areas of the  structural sheathing panels shall be fastened  to a framing member and tracks. Provide blocking or strapping for  unsupported panel edges.

8- foot walls, and 1/3 points for 9 and 10-foot walls.

e.  Load bearing steel studs shall not be spliced without an approved  design.  Splicing of wall tracks only shall be conform with   sheet S2.1. Wall tracks shall not be spliced within 3 inches of studs or anchor bolt locations. f.  Corner studs and the wall intersections shall be installed in  accordance with sheet S2.1.
g.  Stud deflection due to wind load shall not exceed L/360

Light Gauge/ Cold Formed steel Code 

Fire rating are expressed in terms of hours. Fire rating refer to the length of time it takes a fie to burn through a wall. A 1-hour fire rating can be achieved for both load bearing and nonbearing steel walls from 5/8 inch drywall on both sides of the stud wall with no insulation in the cavity.

The United States Gypsum company (USG) has tested fire and  sound ratings for many different wall assemblies using USG products and ASTM standards. The results are published in USG’s Construction Selector ( United States Gypsum company, Chicago, IL,, publication No. SA100/3-99) Web: wwww.usg.com,

Light Gauge/ Cold Formed steel CodeLight Gauge/ Cold Formed steel Code

Light Gauge/ Cold Formed steel Code 

 

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Precision Structural Engineering, Inc.
250-A Main Street, Klamath Falls, OR 97601
Telephone: (541) 850-6300
Fax: (541) 850-6233
info@structure1.com

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