July 4, 2012

Architecturally exposed structural steel guidelines gaining traction

More projects are including architecturally exposed structural steel in their design.

DON PROCTER

correspondent

Despite the rise in popularity of exposed structural steel over the past two decades, until recently steel specification guidelines were only available for standard structural steel.

That changed with the introduction of the Canadian Institute of Steel Construction (CISC) Guide for Specifying Architecturally Exposed Structural Steel.

Its author, Terri Meyer Boake, said he hopes it will become a bible for the industry.

Standard structural steel guidelines fail to address requirements of architecturally exposed structural steel (AESS).

That can result in soaring project costs when excessive requirements for exposed steel are added — often done simply out of ignorance on how to effectively specify the product, she pointed out.

The guide is just that — a guide.

But, aside from the cost-savings benefit, there are other reasons for architects, engineers and fabricators to rely on it.

“Down the road they’ll have fewer arguments and they are less likely to have lawsuits,” said Meyer Boake.

Released last year, the guide has already become important to a number of major steel companies, including Walters Inc., which uses it on all projects where AESS is specified, she said.

Associate director of the school of architecture at the University of Waterloo, Meyer Boake has worked with the CISC since the mid 1990s on developing educational products to help students better understand steel and its applications.

She recently published Understanding Steel Design, An Architectural Design Manual through Birkhäuser.

She sees AESS as important to the steel industry because it shows off steel in an oft-times spectacular fashion.

“We’re seeing a big increase in the use of exposed steel, if not for the whole structure, maybe for the atrium, entrance area or a canopy,” she said.

The guide’s author said the specifications can’t adequately be covered in the regular specifications for structural steel because AESS usually requires detailing, fit, finish and handling that require more attention and care than regular structural steel.

For example, it lays out a framework for the level of finish a product might require in a given application.

How visible the steel is has a bearing on what finish is appropriate.

If the steel is located high above a lobby in an atrium, then a rougher finish, where welds are not hidden, might be specified is a case in point, she said.

The level of paint finishes, fire protection coatings, galvanizing, bending and steel castings is also affected by level of visibility.

The guide also deals with the shipping, handling and erection of AESS.

It even includes scenarios where padding slings are required at erection to avoid damage to the finish.

From the outset of the guide’s genesis, it was important to get input from architects, engineers and fabricators on the content of the specifications — done through several roundtables across Canada — because each discipline has a different view on specification content, Meyer Boake said.

Architects are after aesthetics, engineers want load path requirements met and fabricators are left figuring out how to satisfy both professions’ needs, she pointed out.

Many additions to major airports in North America are incorporating AESS.

Chicago’s O’Hare International Airport’s United Airlines terminal, constructed in 1987, was the first large airport in North America to use AESS.

The CISC adapted components of the American Institute of Steel Construction’s guidelines published in 2003, but the Canadian AESS guidelines go further.

“Our visual guide is far more comprehensive and our matrix is more specific (to projects),” she said.

Meyer Boake said the guide stipulates that the steel must satisfy the requirements of the structural steel specifications and additional specs for AESS.

It includes descriptions of steel application categories with associated characteristics and rough costs.

Also included are images of samples and projects, as well as information on bolted and welded connections.

An appendix to the CISC’s Code of Standard Practice for fabricators dictates how to construct the steel.

A sample AESS specification document is provided for engineers to supplement the structural steel specs.

While exposed steel is thought of as a relatively new trend, some of the earliest structures in the 19th century were exposed, including the Eiffel Tower and many famous bridges.

The new guide is available in pdf format or printed copy.

For more information or to order a copy visit www.cisc-icca.ca.

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