compression load of 1,150 kN and a tension load of 550 kN,
and piles of cast-in-place concrete 700 mm in diameter and
55 m long, each supporting a compression load of 3,050 kN
but no tension load, according to the SIADR information.
Although the building is intended to be a landmark structure in the area, its height was limited by the site’s proximity
to the airport, Gatto says. Therefore, it became necessary for the
roof and cladding systems to make a “memorable impression”
both from a “bird’s-eye point of view” as passengers fly into or
out of the city and from the viewpoint of drivers on their way
to or from the airport on the major highways that pass near the
Hongqiao SOHO site, Gatto explains.
To that end, the London office of the international engineering firm Thornton Tomasetti was selected to provide full facade
consultancy services on the project, including drawings, specifications, calculations, and the detailing of the facade design,
notes Sergio De Gaetano, CEng, a Thornton Tomasetti vice
president and the director of the firm’s building skin practice.
Thornton Tomasetti also brought to the project its detailed
knowledge of the cladding market in China from such projects as the 632 m tall mixed-use Shanghai Tower, now under
construction in that city (see “Cagelike Frame Will Support
Shanghai Tower’s Twisting Curtain Wall,” Civil Engineering,
March 2012, pages 14–16).
Among the numerous design challenges faced by the facade
engineers were the curving, inclined forms of the building’s
four sections; the potential movements and deflections of the
bridges linking the four sections; and the upper-level segments
in each section that span the six-level-high voids. These seg-
ments, notes De Gaetano, technically act like bridges and pose
the same problems in terms of “tricky wind load situations.”
To help minimize the thickness of the facade design el-
ements, which are intended to create a slim, transparent
appearance, Thornton Tomasetti worked with Shanghai’s
Tongji University to carry out a series of wind tunnel tests.
These tests indicated that the actual wind loads on the facade
would be lower than the wind loads calculated by a strict
reading of the Shanghai building codes for structures with
curvilinear forms and numerous recessed corners; the codes
alone would have resulted in the use of more robust and,
therefore, less transparent and more expensive framing ele-
ments in the curtain wall, notes De Gaetano, but the use of
wind tunnel testing was deemed an acceptable alternative for
determining the actual loadings. A map of the pressure loca-
tions generated by the wind tunnel tests indicated that the
glass and framing would have to accommodate wind loads
ranging from 1. 5 to 2. 5 kN/m², De Gaetano explains.
The 86,000 m² mixed-use Hongqiao SOHO project will feature four curvilin- ear sections that create a form inspired by Chinese calligraphy. Located near Shanghai Hongqiao Inter- national Airport, the office and retail complex should be completed by 2013.
SEPTEMBER 2012 Civil Engineering