Dorton Arena - Pushing the Limits: New Adventures in Engineering - page 88

system that made the pavilion stand, and he would later extend the principles of the building's long-
span cable-net roof to structures such as the Yale Ice Hockey Rink in New Haven, the Reception
Building at Dulles Airport, and the circular-roofed Madison Square Garden in New York. Severud
Associates, as the firm is now known, was also the engineering firm for such projects as the Gate-
way Arch in St. Louis, the Denver International Airport, and the Solomon R. Guggenheim Museum
in New York.
Whatever changes mechanical principles would force in the details of Nowicki's conceptual
design for the structure, Deitrick was insistent that they be held to a minimum, so that the completed
building look as much as possible “as Matthew would have wanted it.” This is not to say that there
was no room for creative engineering and construction, for Matthew Nowicki did not leave much
beyond his sketches. Among the practical details that remained to be worked out were how the
building, once designed in detail, would be constructed. This task fell to William Muirhead, a con-
tractor from Durham.
Most structures are built from the ground up, of course, and so the livestock-judging pavilion
began with foundation work: footings for the columns, walls for the basement, and the arena floor.
Like the men in the anthropomorphic model, the two leaning parabolas, which the weight of the
roof would tend to make slide past each other, had to be able to push against something to keep
that from happening. Thus, underground concrete abutments were constructed to take the thrust,
and these abutments were connected by tunnels through which steel cables could pass to connect
the bases of the parabolas to each other. The cables further check any tendency for the bases to slide
apart, which would bring the parabolas closer together and let the roof sag below its desired profile.
The steel columns that support the concrete parabolas were erected next, thus providing perches
onto which a wooden form could be constructed to hold the concrete until it set. (A special mix of
concrete was used so that it would stay put until set and not run down the twenty-two-degree in-
cline of the parabolic legs.) Among the many elegant details of the design is the use of the outside
columns also as mullions to hold the window frames and glazing in place. The columns, spaced six
feet apart, thus serve an efficient, dual purpose.
The roof was put in place by first installing steel cables to span the space between the backward-
leaning parabolic arches. To insure that connecting hardware was located in the right places to re-
ceive the ends of the cables, careful surveying work had to be done to transfer precise locations
into the concrete formwork. The surveyor responsible for overseeing that everything was where it
should be was John R. Gove of Chapel Hill, the third of the North Carolina cities that establish the
vertices of the state's Research Triangle. In an early use of a digital computer, the locations for the
cable sockets were precisely calculated from equations describing the arch. Each cable had to be
accurately sized beforehand, so that it hung with the proper sag. (The finished roof would have a
maximum sag of about thirty-one feet over the three-hundred-foot span.) There are actually two sets
of cables in the roof, at right angles to each other, forming the so-called cable-net.
It was originally thought that the roof would be covered in some kind of fabric, but, as often hap-
pens in building, what was available when construction bids were submitted was considerably more
expensive than an alternative. To save money, the cable-net was thus covered with corrugated steel
panels, on top of which was placed insulation, and on top of that conventional waterproof roofing