BLOG ENTRY - 14 AESS 1

 

Hey guys! 

In this blog we are going to see what Architecturally Exposed Structural Steel (AESS) and the first category, AESS 1 in detail with examples.

What is AESS?

Architecturally exposed structural steel, aess, is steel which is purposefully left exposed while designed to structurally support the building and its connecting members and therefore is a significant part of the architectural language of the building.The design, detailing and finish requirements of AESS will typically exceed that of standard structural steel that is normally concealed by other finishes.  

Factors of influence that define AESS: 

- Distance. Visibility. 

- connections - bolted/ welded

- Tolerances required at fabrication and erection 

- acess to detail to perform required finish 

- degree of expression

- size and shape of structural elements 

- interior or extrior setting 

- paint finish, corrosion resistance and fire protection

THE CATEGORY APPROACH:

- The viewing distance (greater or lesser than 6m) 

- the type or function of the building 

- a range of potential cost increase

AESS CATEGORY 1 - BASIC ELEMENTS 

This category applies for ''basic elements'' which require enhanced workmanship.

- specified for ceiling elements of design where distance to view is in the 6m or greater range.

- Straight forward design 

- relatively large viewing distance as well as the lower profile nature of the architectural spaces in which it is used.

- a) standard structural members are aligned in a uniform way - b) spacing is kept consistent -

c) surfaces of the members are properly prepared to accept uniform finishes and coatings

- found in roof trusses for arenas, warehouses, big box stores and canopies 

- fairly straightforward section types such as W, HSS, and often OWSJ and exposed profiled decking.

- may or may not require special fire protection design. Steel may be left completely unprotected, or sprinklered, and so it will need to receive only a paint finish. 

- Intumescent coating may be given. 

CHARACTERISTICS OF AESS 1 CATEGORY:

-The surface preparation of the steel must meet SSPC SP-6.

- All of the sharp edges are to be ground smooth.

- continuous weld appearance for all welds.

- bolted connections - standard structural bolts.

- Weld splatters, slivers, surface discontinuities are to be removed.


EXAMPLE 1- Semiahmoo Library, Surrey, B.C.

ARCHITECT - MCMD

FUNCTION - LIBRARY 

LOCATION - CANADA 

YEAR OF COMPLETION - 2010

- simple exposed structure comprised of W sections and OWSJ with a painted finish. Standard steel framing, clerestory windows and supplemental task lighting. 

- extra care required in the preparation and installation of the members.

-The W sections are exposed to view and touch, but overall the ceiling elements are viewed at a distance. 


 







(1) Roof overhang that exposes the steel framing and underside of the steel decking. This overhang is used to provide solar shading for the clerestory windows.














(2) The exposed interior steel framing makes use of standard steel framed connections.




How did this project fall under AESS 1 and not AESS 2? 

If this project used custom trusses instead of OWSJ members, it would likely have fallen into AESS 2 Category Steel. 

But in order to save on the use of finishes, the steel has been left exposed, which has helped in achieving credits towards a LEED Silver Rating. (lower cost premium with standard joists).


EXAMPLE 2 - Ricoh Centre, Toronto, ON: 

ARCHITECT -  Zeidler/Dunlop

FUNCTION - EXHIBHITION PLACE  

LOCATION - TORONTO, ON 

YEAR OF COMPLETION - 1997- INFRASTRUCTURE RENEWAL- COMPLETION - 2003 

- The renovated project uses curved trusses adjacent to the entry area of the arena to reflect the curved window of the adjacent historic facade. 

- the trusses are fabricated with HSS material. 

- Above 6m from the viewer, hence the viewers dont hold a close up view of the finishes and connections. 

- More effort involved in the fabrication process. No off-the-shelf components were used. 








(3) The project uses a combination of standard steel shapes, HSS and curved sections.











(4) The curved steel memebers are paired C channels separated by a central spacer.









(5) detail of one of the truss connections.



Why does this project fall under the AESS 1 category?

- Closer span between the trusses 

- less refined nature of space

- Roughly detailed design style 

- low cost premium through the use of - standard sections and connections. 





REFERENCES:

(1), (2)- https://www.tboake.com/steel/semiahmoo.html

(3),(4),(5) - https://www.tboake.com/steel/national_trade.html

https://www.tboake.com/2017/2017_570_CONNECTIONS.pdf

https://www.tboake.com/SSEF1/what.shtml

https://cisc-icca.ca/ciscwp/wp-content/uploads/2017/03/AESSGuide2E.pdf


Signing off, 

Tejashri Kumaresan 











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