Presentation from the Banff Conference 2018 by the Alberta Institute of Architects. Presentation sponsored by CISC.

1. Complexity Meets Craft:
INNOVATIVE STEEL DETAILING
in ARCHITECTURALLY EXPOSED STRUCTURAL STEEL
Terri Meyer Boake
University of Waterloo

2. This presentation has been generously sponsored by

3. Terri Meyer Boake
Professor
School of Architecture | University of
Waterloo
tboake@uwaterloo.ca
http://www.tboake.com
2018

4. What is AESS?
• Architecturally Exposed Structural Steel is steel
that has been purposefully left exposed
• It must fulfill structural functions
• It is normally part of the Architectural
aesthetic of the space
• It usually requires detailing, finish and handling
that requires more attention and care than
regular structural steel
• It adds to the cost of the contract

5. Standard Structural Steel
• The initial point of technical reference is
Standard Structural Steel as it is already an
established and well-understood as a
baseline in construction Specifications.
Predominant use of standard structural
steel shapes, OWSJ, exposed decking

6. AESS 1 - Basic Elements
• the first step above Standard
Structural Steel
• suitable for "basic" elements, which
require enhanced workmanship
• should only require a low cost
premium in the range of 20% to 60%
due to its relatively large viewing
distance as well as the lower profile
nature of the architectural spaces in
which it is used.
Uses a lot of standard structural steel
shapes, some HSS, OWSJ, exposed
decking

7. Roof trusses
for arenas, retail
warehouses,
canopies
Cost premium: Low
(20-60%)
AESS 1

8. AESS 2 - Feature Elements (> 6 m)
• structure that is intended to be viewed at a
distance > 6 m
• The process requires basically good fabrication practices
with enhanced treatment of welds, connection and
fabrication details, tolerances for gaps, and copes
• might be found in retail and architectural applications
where a low to moderate cost premium in the range of
40% to 100%
• Uses a lot of standard structural
steel shapes, some HSS, exposed
decking
• Bolted connections and
unremediated welded connections

9. Retail and architectural
bldgs viewed at
a distance
Cost premium: Low
to Moderate
(40-100%)
AESS 2

10. AESS 3 - Feature Elements (≤ 6m)
• structures that will be viewed at a distance ≤ 6m
• suitable for "feature" elements – where the
designer is comfortable allowing the viewer to see
the art of metalworking
• welds should be generally smooth but visible and
some grind marks would be acceptable
• weld grinding is permitted but not encouraged
• Increased use of HSS over standard
structural shapes
• Some curvature in members
• More welded than bolted connections

11. Airports, shopping
centres, hospitals, lobbies
Cost premium: Moderate
(60-150%)
AESS 3

12. Viewing distance is noted as the
differentiating factor between the high and
low end AESS Categories.
Grinding
permitted $$
No
Grinding!!

13. AESS 4 - Showcase Elements
• used where the designer intends that
the form is the only feature showing
in an element
• All welds ground and filled edges are
ground square and true
• All surfaces are sanded and filled.
Tolerances are more stringent,
generally to half of standard tolerance
for standard structural steel
• Large amounts of custom plate work
• Remediated (and unremediated) welded
connections
• Large custom castings
• Machined steel

14. Showcase or dominant
elements, sculptures
Cost premium: High
(150-250%)
AESS 4

15. PUSHING CREATIVITY IN ARCHITECTURALLY EXPOSED
STRUCTURAL STEEL
Computation methods evolve at such a rate as to make much
printed discussion of them rapidly out of date
This presentation instead looks at the important lag between
the design and fabrication of complex steel structures.
Highlighted are:
• issues of the increased importance for tight tolerances,
• Innovative methods for ensuring a quality outcome
• team coordination/communication
in this still largely craft based system
Important accommodations that are required to ensure the
proper fabrication and erection of Architecturally Exposed
Structural Steel.

16. Architectural design has left this behind....
Design for constructability
must address new issues.
I love Mies

17. 2006

18. Non orthogonal geometries in steel demand new methods of working.
Image: Walters Inc.
So many
curves, and
it’s not even
symmetrical!?

19. Digital technologies have enabled increasingly complex projects
Image: Walters Inc.
Not a standard
detail or
connection on
this project!

20. Thankfully software has kept ahead of the curve(s or angles)
Image: Walters Inc.
With current
software I can
design
anything, but
can it be built?

21. Image: Walters Inc.
BUT fabrication and
erection methods
have had to keep up
with the challenge

22. The Root of the Problem is with the expectations of Complex Design….

23. Addition to Royal Ontario Museum, Toronto - 2006

24. Translating 3D models to physical visualization

25. Fabrication is still largely CRAFT BASED

26. Digital
programs can
create highly
precise drawing
sets

27. That must be
shop fabricated
using fairly
standard
methods.
And erected
using fairly
standard
methods.

28. Lifting points
are a challenge
to place due to
eccentric loads
that defy
gravity
assistance

29. Ironworkers are
left to the
challenge of
fitting the
components
But this wasn’t even AESS

30. Brookfield Place | New York City

31. 3D printed maquette of the proposal

35. Image: Walters Inc.

36. Image: Walters Inc.

38. Access for welding
needs to govern the
spacing of the
tubes

39. Maximize shop fabrication
for better results and
more humane working
conditions

40. Geometric
control during
fabrication

41. Test erection in shop prior to shipping

43. Skills and problem solving
abilities are critical on the
job.
Complex structures require new
approaches to erection

44. Glad I didn’t eat too
much last night! This
is a tight fit.

46. Splicing Steel
• has a HUGE impact on design, fabrication,
erection
• Usually done between sections of larger elements
• Usually the result of transportation limitations
• Usually intended to be as unobtrusive as possible
• Normally downplay the connection
• Three standard ways when dealing with HSS:
• COMPLETELY REMEDIATED SPLICE BY
WELDING TO THE POINT OF INVISIBILITY
• HIDDEN CONNECTION USING BOLTS AND A
COVER PLATE
• DISCREET CONNECTION WITH EXPOSED BOLTS

47. Canadian War Museum | Ottawa, ON

48. Concert Hall | Boston, USA

49. Stadium | Perth, Australia

55. Grinding to ensure a precise fit

56. Precision key due to seamless final appearance

57. Scaffolding to provide good access for quality welding and remediation

59. Seattle Public Library | Seattle, WA

60. Discreet, bolted connections

61. Olympic Park Station | Sydney, Australia

63. Office Building at Potsdamer Platz | Berlin

65. Masdar City | Abu Dhabi

67. Melbourne Theatre | Melbourne, Australia

69. 100 Eleventh Avenue | New York, NY

71. Federation Square | Melbourne, Australia

73. Calgary International Airport | Calgary, Canada

74. 3 Segments
T1 = 13.5m
T2 = 18.2 m
T3 = 26.3 m
L = 58.0m
2 Splices
Image: RJC

78. How to Create a Cone
• Always a custom shape
• Made via brake forming
• Done in sections and welded together
• Always a higher level of AESS (likely an AESS 4)
due to the grinding and finishing requirements
in order to make smooth the connection with
the adjacent tube

79. Cones are made using a brake press

80.  Tapered tubes are not manufactured as shapes
 ALWAYS created through brake forming

81. Fabrication and Erection:
Walters Inc. OCADU | Toronto, ON

84. Amgen Bridge | Seattle, USA

85. 85
Barajas Airport | Madrid, Spain

86. distance factor

87. Elliptical Tubes
• New HSS product that is available
• Only comes in 1:2 proportion and limited range
of overall sizes
• Popular where a more slender appearance is
desired

88. distance factor

89. distance factor applied!

91. Neo Bankside Housing | London

92. Plate set inside tube
Plate cut into tube

93. End Connectors – Pin Connections
• Becoming a standardized detail
• Used where rotation is desired during the
erection process
• Transfers only vertical and horizontal forces
• Not moment resisting

94. Pompidou Center | Paris, France
It all started
here…

95. Tower Bridge House | London, UK

96. Bullring Shopping Center | Barcelona, Spain

97. Heathrow Airport | London

99. Barajas Airport | Madrid, Spain

102. Pearson Airport | Toronto, Canada

103. Ottawa International Airport | Ottawa, Canada

104. Cutty Sark Museum | London, UK

106. Calgary International Airport | Calgary, Canada

109. Tensile Connections
• Dealing with an entirely different language due to the
slenderness of the members
• Connections for rods versus cables
• Mediating the overall size of the small diameter members
as they connect to larger structural types
• Predominantly either:
• End connections (PINS) that use clevises
• Center points of cross bracing
HUGE OPPORTUNITY TO TALK ABOUT FORCE DIFFERENTIATED
STRUCTURES!

110. Pompidou Center | Paris, France

114. Reichstag | Berlin, Germany

115. International Airport | Porto, Portugal

116. Kurilpa Bridge | Brisbane, Australia

118. Jubilee Bridge | London

120. Sony Center | Berlin, Germany

122. Woah!
Huge!
Tokyo International Forum

123. How did
they erect
this??
Defense Shopping Center | Paris

124. How to Create a Corner
• When the “corners” on an HSS tube are
too rounded for the desired aesthetic,
and crispness is desired
• Usually the point when custom
fabrication of the members using plate
steel is required
• Major decision on the corner will impact
cost”!
• $ - Inset corner allows fillet welding
• $$ - butt corner with unremediated welds
• $$$ - butt corner with fully ground welds

125. This still qualifies as AESS 4 due to its precise finishing
and weld grinding, but the HSS has rounded corners that
might not be visually acceptable for some designs.

126. Siemens Crystal | London, UK

128. Newseum | Washington, DC

132. Puente de Luz | Toronto

134. Arganzuela Bridge | Madrid, Spain

137. ABC Museum | Madrid, Spain

139. Contemporary Cast Connections
• Used to simplify connections
• Able to locate physical (welded) connections away from
areas of high stress
• Used for special connections
• Used for standard connections
• Can be one-of large pieces formed with expendable molds
(i.e. Structural)
• Can be smaller die cast pieces made in great quantity (i.e.
glazing attachments)
• Can be solid or hollow depending on size and purpose
• Generally either NODES or END CONNECTORS

141. When did the term
NODE enter our
structural vocabulary?

143. Image: Courtesy Walters Inc.

146. Berlin 1936 Olympic Stadium Retrofit

148. Queen Richmond Centre | Toronto, Canada

149. Image: Walters Inc.

152. Castings designed by CastConnex
31,500 pounds
of cast steel

156. Image: Courtesy CastConnex

157. The New Whitney | New York, NY

159. Transbay Center | San Francisco
Image: Courtesy CastConnex

160. Image: Courtesy CastConnex
SCALE!

163. Splice moved away
from point of load
transfer.
Welded splice set away from the reveal to
take your eyes away from the site weld.

164. Image: Courtesy CastConnex

165. EMPOWERMENT
IS IN THE DETAILS
STEEL

166. The Culture Shed | New York City

168. Images: Thornton Tomasetti

169. NODE

171. Discreet cutout
panels to allow
access to the
interior to
tighten the
bolted
connections.

173. Phoenix New Media Center | Beijing, China
The most parametric
building in the world…

174. Amazon Spheres | Seattle, WA
http://uk.businessinsider.com/amazon-seattle-biosphere-construction-tour-2016-8

175. Conclusions
Although the digital tools for design have
advanced substantially in the last 20 years, steel
structures that employ non orthogonal, chaotic
and curved geometries continue to require a
higher level of communication during the design
process in order to ensure detailing that
acknowledges that the idiosyncrasies of these
structures place much of their fabrication outside
of automated processes.
Fabrication processes and erection considerations
must be acknowledged as a valid concern when
vetting aesthetically driven considerations.

176. This presentation has been generously sponsored by

177. Terri Meyer Boake
Professor
School of Architecture | University of
Waterloo
tboake@uwaterloo.ca
http://www.tboake.com
2018