Standard Calculations: Cold-formed Steel Portal Frame; Maximum Span 21m


An invoice will be emailed, and it can be paid by cheque or internet banking.

Requirements (inputs)
Name and address of buyer email address

Deliverables (outputs)
The report will be in pdf format and delivered by email, along with invoice for the work.

The Product:
Structural calculations for the structural product as described below.

The Structure:
Standard fixed base moment frame forming doubly pitched roof (gable), connected by bolting plates welded to ends of the members. The design methodology for the end plates and accounting for localised effects at the column was validated by testing prototypes at the University of South Australia.

Roof Pitch: 10 degrees
Building Width21m (face of girt to face of girt)
Eaves Height: 3m
Frame Spacing3m

Importance: Level 2
Earthquake: not significant therefore not considered
Snow not significant therefore not considered
Wind: Region A, Terrain Category 3, flat topography, no shielding, Cpi[-0.3,0,0.4]

Time Frame
If the project is accepted , then 1 week to 12 weeks depending on current workload.

Future Releases:
At some future date this report, and all similar standard reports will be available for immediate digital download. Additional licensing will be available for creating derivative works such as creating a composite report describing a whole building system.

Possible End-Users:
1) The report is primarily for manufacturers and other suppliers of structural products.
2) The report may also be useful to suitably qualified structural steel designers who.

  1. Do not have software for frame analysis or cold-formed steel design.
  2. May want a worked example or point of reference.
  3. Want to save time documenting such frames: by checking once and certifying report in its own right, and then certifying again as suitable for a specific project and incorporating in larger report for whole building.

Other Notes:
1) Excluded:

  1.     Answering local government authority queries with respect to suitability for a given building project
  2.     Answering queries from others with respect to suitability for a specific project.

For those in need of regular assistance, subscriptions to a “structural help desk” will be made available in the near future.

2) This is not a full building and excludes:

  1.     Roof Bracing
  2.     Wall Bracing
  3.     Roof Purlins and Cladding
  4.     Wall Girts and Cladding
  5.     End Walls (mullions and other framing)
  6.     Door framing
  7.     Transfer beams and side frames at doors
  8.     Cropped Portals

For a building system providing a range of buildings, these excluded components are often consistent throughout the range. Therefore standard calculations for a building system can cover these components once for the entire range and are considered better presented as separate reports. Other items such as cropping the portals and design of gable end walls require custom design to suit the needs of the building.

3) The structural form is a moment frame: the rafters and columns are as if a continuous single structural element. Removing columns to insert doors wider than the frame spacing, cripples the frames and reduces the resistance of the building to the transverse wind, that is the wind which blows across the roof. Simply inserting a transfer beam or carry beam to carry the rafters is not acceptable. Such building requires custom design. Alternatively select a standard design with frames spaced greater than the width of the required doors/openings should be used. {Consider a dual lane road of 5.5m, then with 1m footpaths either side, then frames for such entrance/exit would need to be spaced at greater than 7.5m}

4) The 3m frame spacing comes from the maximum span that the girts and purlins have, which are typically used by the shed industry (eg. C75’s or small tophats). Therefore the entire building should be set out on a 3m grid, with expectations that end wall framing will also have mullions or end wall columns at 3m centres.

NB: The now more common gusset plate or bracket connections are typically proprietary. Such connections can be modelled using FEA/FEM, but such computer models are approximate only, and need to be validated and calibrated against testing of physical prototypes. If wish to have standard calculations using such brackets,then the supplier of such brackets need to provide a technical specification identifying the maximum combined resistances the brackets have (phi.Ms, phi.Nc, phi.V, phi.Nt) or a statement that the brackets can develop the full
capacity of the sections being joined: given the bolting configuration in some of the brackets it is highly unlikely that they can develop the full capacity of the c-sections which are connected.

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