AESS Custom Category - Blog 14

This blog is about Architecturally Exposed Structural Steel i.e. AESS, elaborating on the CUSTOM category of AESS.

AESS is a type of steel that is used for ancillary structures and is exposed at the same time rather than Standard Structural Steel which are used a columns, beams and girders often concealed by finishes like concrete etc. AESS developed as the requirement of steel widened from using it as only structural element to using it as aesthetical, feature and joinery. 

AESS required a detailed approach in industrial design standards when producing joints, members and connections which give the structure its distinctive character. These exposed structural system sometimes become the architectural trademark highlighting or emphasising the building or structure in which it is used. Therefore, the involvement of the Designer, Engineer, Fabricator and Erector is required on an equal amount to get the desired output.


There are a few factors which influences in defining the AESS type steel which are as follows:

  • ·        Connections: Either bolted or welded vary from different levels of finish.
  • ·        Tolerance: It is done during fabrication and erection based on function and complexity of the structure.
  • ·        Detail: workmanship is concerned based on its location and the tools required for doing it.
  • ·        Degree of expression: How the connections and complexity of structure are shown.
  • ·        Size and Shape of structural elements:  The approach to detail and finish
  • ·        Interior or Exterior setting: weathering, fire protection and damage impact potential.
  • ·        Finish, Corrosion Resistance, Fire protection: Depends on the thickness, surface preparation, connections and joinery.

All these factors can be combined to get the FORM, FIT and FINISH where the design, structure and aesthetics are concerned.


AESS is further divided into categories based on the factors of influence mentioned above but primarily based on the following factors:

  • ·        Viewing distance ( greater or less than 6 metres
  • ·        Type or function of the building ( this gives the design requirements for finish )
  • ·        Range of potential cost increase ( compared to standard structural steel )
AESS CATEGORIES:

  • ·        AESS-1: Basic elements.
  • ·        AESS-2: Feature elements viewed at a distance greater than 6 m .
  • ·        AESS-3: Feature elements viewed at a distance less than 6 m.
  • ·        AESS-4: Showcase elements.
  • ·        AESS-C: Custom elements.
  • ·        Mixed Category

AESS C - CUSTOM ELEMENTS:

It was made to create custom elements for any of the characteristics and attributes used to define the other categories which require a different set of characteristics as specified in Category 1, 2, 3 or 4. These elements require high level of communication between the architect, engineer and the fabricator. This category uses reduces steel for sustainable purposes and steel that is less refined is used purposefully for its characteristics. The custom elements have extra fabrication that is used for unusual finishes. Custom category will also provide an ability to create sculptural elements in nature. Some paces the element as to be highlighted and in some it has to be closed and concealed. The former requires less amount of care and workmanship than the latter. Stainless structural steel comes under this category as it has different specifications and high level of installation.

CHARACTERISTICS OF AESS – C:

This category provides flexibility in the design of steel with a high cost premium of 20% to 250% over standard steel. The complexity, size, level of finish and types of members in custom category is different from other categories leading to its high cost premium.The areas that are taken into consideration for AESS custom projects are:

  • ·        Large oversized members
  • ·        Extraordinary geometrics and curved members
  • ·        Accessibility issues
  • ·        Unusual finish requirements
  • ·        High levels of grinding and filling for connection
  • ·        Transportation problems as the member sixe is very big
  • ·        Difficult handling and extra care for pre painted products.


Some examples of how AESS C category  steel is used are as follows:

HEATHROW TERMINAL 5, LONDON.

Ar. Richard Rogers designed a space as a large free standing structure with single span roof which required custom made joinery and large connections. The connections in the airport is a combination of custom work for hinge, casting and the HSS members and the truss members to the hinge. This showcases high level of fabrication and finish for the column supports and legs.


 ANGUS TECHNOPOLE, MONTREAL.

It is a former locomotive shop which turned into office and commercial space. The riveted steel left behind was not completely cleaned and painted so the new elements added needed a custom specification to make the new elements fit into the aesthetics if the old building.

    

UNIVERSITY OF GUELPH SCIENCE BUILDING COURTYARD

The structural tree that stands in the centre of the courtyard uses special castings to cleanly join the pipe with unusual welding and filling connections. This also requires grinding the surface of the casting to match the surface condition of the adjacent pipe.






      

Thanks for reading!

-Theerthana.✌


REFERENCE:

CISC Guide For Specifying Architecturally Exposed Structural Steel.










Location: India

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