scope

August 7, 2015 § Leave a comment

IMG_2117OK, so the gig in Norfolk has been interesting to me for many reasons, but one of them was the Scope Arena, one of Nervi’s least-known–but most intriguing–collaborations.  The folks at HEWV were great about getting access for me and about twenty of their staff this week, and to introduce me to Bradford Tazewell, one of Norfolk’s legendary architects and the site architect for the Scope project and the adjacent Chrysler Hall.  Tazewell’s recollections were sharp and he helped answer some of the questions that the archives hadn’t answered.

The Scope was conceived in the aftermath of two events: the razing of much of downtown Norfolk in the U.S.’ ‘model cities’ program, and the global broadcast of the 1960 Summer Olympics in Rome.  With lots of empty downtown space to fill and a desperate need to attract people to downtown, city leaders took advantage of their strong political connections to convince the federal government to replicate its sponsorship of a cultural complex in Denver in the northeastern corner of Norfolk’s decimated urban core.  Having seen Nervi’s domes on the Olympic broadcasts, Tazewell convinced the city to hire Nervi as a design engineer, with his firm, Tazewell and Williams, serving as architects of record.  The project was built between 1968 and 1971, and while Nervi prepared plans for both the arena and the performing arts center, ultimately Tazewell and Williams designed the latter–in Mr. Tazewell’s recollection, Nervi’s design was more of an opera house than a concert hall, and his real interest lay in the dome.

IMG_2130And it’s quite a dome–134m span and about 35m from floor to the top.  Nervi adapted the tavelloni method that he’d used on the Palazetto dello Sport but with a couple of changes that had evolved in other projects during the 1960s.  Most importantly, the shape of the pans for Norfolk is triangular, instead of the diamonds that formed the dome in Rome.  This allowed the system to more easily tile the doubly-curved surface, since a triangle will always sit flat on its three points, while a diamond must be kinked to place all four of its points on such a surface.  But the triangular pans also produced a third set of ribs in the dome’s overall pattern–ribs that are circumferential around the dome and that thus offer resistance to any hoop stresses that develop (see https://www.iass-structures.org/index.cfm/journal.article?aID=670.  FWIW, ace ISU grad student Kyle Vansice has some interesting finite element analysis work that he’ll be presenting at this year’s IASS conference in Amsterdam later this month that–gently–challenges some of this paper’s conclusions).

IMG_2128The other slight change is the detail where the pans come together.  Nervi had typically plastered the joint between adjoining pans over, making the roof of the Palazetto read as purely structural ribs and disguising the modular nature of the ferrocemento formwork.  But while working with Harry Seidler on the Australia Square tower, Seidler questioned this detail.  In a letter dated 4 August, 1965, Seidler notes:

Your details show quite a large V-joint between units as well as a tolerance gap. I presume that you intend for this groove to remain so in the final installation and that you do not intend for it to be filled up as I know you have done in some of your floors, such as in Turin.

Since finding this last year I’ve never quite known what to make of it, but there’s a part of me that really wants to believe this is Seidler gently correcting Nervi’s instincts.  Plastering the joint over conceals an important element in the expression of the construction process–leaving one to think that the surface of each rib is really the surface of the concrete itself.  But it’s not, of course.  What we’re seeing is the surface of the formwork pan.  Nervi agreed quickly to Seidler’s suggestion, and in all of his subsequent work, including the Scope, he kept this joint open, as you can see in the detail photograph above.  It adds a shot line to each rib, of course, visually emphasizing the pattern, but it also reveals the thickness of the pan, and visually explains the modular nature of the construction.  (Subtle evidence that this was Seidler’s innovation comes from subsequent correspondence from the Studio that noted Nervi was “of the opinion of leaving unfilled the ‘V’ joint between the units, considering that in the photographs it appears perfectly finished”).

The Scope has an interesting section in that the seating bowl is literally separated from the dome by several feet–this has been closed up now for safety reasons but it builds on the Palazetto’s idea of bringing in daylight under the dome, emphasizing just how delicately it’s propped up in the air.  Tazewell noted that this also represented a split in design responsibility–Nervi had almost exclusive control over the dome itself, but agreed to leave the design of the seating bowl entirely in the hands of the local architects and engineers.  It’s substantially different from the Palazetto, however, in that the tension ring preventing the dome from flattening out was moved from underground (the solution in Rome) to the base of the dome proper, above the concourse, supported by massive buttresses.  This was clearly necessary because of the need for a subterranean parking garage that would have pushed the tension ring well below the water table, but it does lead to a very different reading of the dome from outside–instead of the light, ‘pie crust’ edge at the Palazetto, the Scope has a rather heavy ring beam enclosing the steel tension ring.

IMG_2103This also, I suspect, is one reason that the buttresses in Norfolk are much heavier than those in Rome, though here they employ the twisting board forms that evocatively combine a record of construction and an intuitive hint at their performance.  The forking configuration of the ones here isn’t matched anywhere else in Nervi’s work, and combined with concrete ‘feet’ at the plaza level that recall the massive piers of St. Mary’s Cathedral, these piers are particularly sculptural.  (For the record, they taper from vertical blades at the base, allowing the dome to expand and contract thermally around its circumference, to horizontal blades at the top, allowing the dome to expand and contract radially).

IMG_2136Mr. Tazewell talked at length about a genuine mystery–at the edge of the dome, inside the dark-tinted glass curtain wall, there’s a ring of thin, tapering columns that are clearly helping to hold the ring beam up against gravity.  These are very obviously redundant statically, in that the tapering buttresses are certainly taking plenty of the dome’s vertical load.  I had thought, seeing them in photographs, that they might be wind bracing for the curtain wall, an idea that was explored for Rome’s large sports palace.  But they’re not connected to the glazing, and they’re shaped just like a good, pin-connected, axially-loaded column ought to be shaped–skinny at the ends, wider in the middle.  Mr. Tazewell recalled that they were added very late in the design process, and rather hastily, and the only conclusion I can draw is that there was some concern about the sizing of the exterior buttresses–probably about buckling, given their slenderness.  If so, it’s evidence of a rare error on Nervi’s part, but also of the conservative streak that marked some of his late work.  This would be a similar story to that of the exterior walls of St. Mary’s.

IMG_2115There are a couple of easter eggs in the complex, including this small bus stop on the complex’ east side made up of pan-formed concrete (in this case the pans appear to have been stripped instead of left in place) and a gloriously stumpy ruled-surface column, both signature elements deployed, I’d guess, with tongue firmly in cheek.

The Scope was at the time the largest span reinforced concrete dome in the world, 13 meters larger than the basketball arena at the University of Illinois (hail, alma mater), which had been finished ten years earlier.  It’s span was beaten in 1976 by Seattle’s Kingdome, but when that came down in 2000 the Scope re-took the record, which it still holds.  Admittedly, it holds the record because steel these days is, by far, a more efficient and cheaper way to build roofs of this span–Singapore’s steel National Stadium more than doubles the Scope’s record.

The building is now home to minor league hockey, concerts, and exhibitions.  There have been additions to the interior that hide much of the original ceiling, beginning with a lighting catwalk that had to be added at the opening to provide enough footcandles to televise basketball games.  And there are plans to replace much of the extant curtain wall, allowing space for much-needed toilets and concession stands.  All of this will, I think, muddy the clarity of Nervi’s work further, but none of it involves demolition of any parts of the Nervi dome or buttresses–which on balance means that the structure will continue to be viable and active and should thus avoid the Kingdome’s fate.

IMG_2091A great afternoon out, both as a Nervi fan and as a onetime Virginia Squires fan.  The Scope’s first tenants were the regional ABA basketball team, though Norfolk shared them with other arenas in Hampton, Richmond, and Roanoke.  So, in addition to Nervi, there may have been some small amount of communing with the spirits of Dr. J and George “Iceman” Gervin…Thanks to all at HEWV and at the Scope for making this happen.

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