Architectural Structural Steel

Structural steel can make a significant contribution to architectural expression. Examples include expressed steel of stairs and exposing and expressing structural form – interior or exterior.

Exposed structural steel can also go wrong – which faults may be immediately evident or only appear over time. The main areas for attention include:

  • Steel member profile and size selections – which may be in excess of structural requirement
  • Fabrication configuration – such as keeping junction welds away from the rear of exposed surfaces
  • Durability protection – for which heavy duty coatings are usually preferable to galvanising
  • Decorative finish coating – over the protective coating

Hobbs + Associates specifications include a specification for “Architecturally Exposed Structural Steel” which has been custom developed by us to cover these matters and more.

The Australian Steel Institute has published* a “Sample Specification (for Engineers) – Architecturally Exposed Structural Steel (AESS)” from which the architect would be mainly interested in “Table 1 – AESS Category Matrix”. (Extract only shown.)

Table 1 – AESS Category Matrix defines several Categories for Architecturally Exposed Structural Steel (AESS Categories), being:

  • AESS 4 for Showcase Elements
  • AESS 3 for Feature Elements – Viewed at a distance up to 6 metres
  • AESS 2 for Feature Elements – Viewed at a distances over 6 metres
  • AESS 1 for Basic Elements
  • AESS C for Custom Elements – an option for custom selection of characteristics
  • SSS refers Standard Structural Steel for which there are only structural requirements

The Categories are defined by an ascending collection of characteristics with the higher levels including all of those applicable to the lower categories.

A collaborative contribution from the structural engineer assists with achieving the intended effect and finish – especially with the selection of member profiles and sizes, and configurations – and connector expression, when used.

Example of fabrication faults in structural steel intended for an exposed architectural staircase.

 * Ref: “ASI/SCNZ AESS Document E: Sample Specification (for Engineers) – Architecturally Exposed Structural Steel Rev 15th Oct 2012” (6 pages)

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