(continued)

The designers then detailed the roof section, which consists of a steel space frame encased in metal cladding. Finally, they used the software to extrude this section along each ribbon's two constraining spline curves. The space frame maintains a constant depth even as the top and bottom surfaces undulate.

These 3D architectural forms were passed electronically to Ellerbe Becket's in-house structural engineers. They converted the data into a software package called Staad, from Research Engineers, Inc., in which they developed a structural analysis model to determine the structural integrity of the building, the thickness of the roof-supporting concrete pylons, and all structural steel roof member sizes. The engineers then exported their model to 2D structural drawings in AutoCAD. Two-dimensional views of the 3D architectural model were also exported to AutoCAD for plan, section, and elevation construction drawings now under further development by the architects of record at the Architectural Design and Research Institute of South China University of Technology.

Proebstle recalls: "Given the constraints of the playing field's geometry, the structural engineering, and the integrity of the design concept, a lot of pushing and pulling of the ribbon occurred. It would have been extremely difficult to understand the shape and keep it graceful if we didn't have the 3D model that allowed us to study it with multiple 'cameras.'" The 3D images will also be useful to the contractor who may use them as well as 2D shop drawings to communicate construction information in the field.

The Chinese government required that ground be broken after two months of schematic design, intensifying the need for speed and precision. Ellerbe Becket director Kyun Kim, AIA, says that this could not have been done if repetitive redrawing had been needed at each phase, as is commonplace with traditional tools. Kim says, "To get input from mechanical, structural, and electrical engineers, and to pull together a package in less than two months is unheard of. The early ground-breaking was scary, but it's working out."

Plunging New Depths

Another project promising to make a splash in architectural innovations is a proposed underwater habitat designed by George Berean, AIA, vice-president at the Honolulu office of Wimberly Allison Tong & Goo (WAT&G). The firm is well known for its design of resort hotels, and this structure will offer a new twist on eco-tourism by combining luxurious guest accommodations with scientific laboratories and observatories.

The habitat will be moored at a depth of 12 meters, connected to a nearby pier with 'umbilical cords' for power, water, and waste. It will be transportable in case of hurricanes or other emergencies yet stationary enough to be classified as a hotel, not a ship. Half of the structure will extend above the water's surface for sun decks and observatories. The developer is currently seeking funding for the first such "U-SEA Habitat," which will probably be sited in Hawaii, Mexico, or Sicily.

WAT&G architect Randy Totel, AIA, who modeled the structure with AutoCAD, claims the design would have been nearly impossible to draw and study without the capabilities of 3D solid modeling software. To counteract high pressure, the underwater portion of the structure is round in plan and the portholes are bubble-shaped lenses. Unnecessary structurally but consistent with the nautical motif, the staterooms' wall and ceiling surfaces are curved and their doorways are arched.

To achieve these forms in the modeling software, Totel drew the rounded shapes in 2D and graphically extruded them into the third dimension. Then, using Boolean operations to add and subtract 3D forms, he was able to figure out how all the curved surfaces intersected. "I don't see how you could do it any other way," he reports. The above-water structure, which is polygonal in plan and pyramidal in section would have been equally difficult to shape without the advanced technology.

Totel made the entire design more comprehensible to clients by creating animations that depicted the unusual forms from a series of vantage points. He created the animations with 3D Studio Max, where he applied material colors and textures and defined the locations, brightness, and other parameters of the simulated light sources.

Designing with Light

The Chinese stadium and the underwater hotel demonstrate that computer modeling makes complex forms more feasible. But design needn't be exotic to benefit from such modeling. When Elizabeth (Zibby) Ericson, FAIA, design partner of the Boston firm Shepley, Bulfinch, Richardson and Abbott approached the design of a skylight at Boston College, she realized traditional media would not suffice because of its geometric complexity.

The skylight was to span a courtyard that was taking shape between a new rectangular building and an existing boomerang-shaped structure. The two buildings had different materials, structural systems, and floor-to-floor heights. The skylight over the narrow polygonal space between them was meant to unify the disparate elements.

"To span the dissimilar buildings," Ericson says, "the skylight had to bend in each dimension. The geometry was quite tricky and just wouldn't come together." With modeling assistance from Harold Hon, who used Bentley Systems's MicroStation 95, Ericson was able to study dozens of ways to structure the skylight. The final design looks deceptively simple, without a hint at the actual complexity. It resembles a filigree-like trellis more than a steel resolution to several intersecting structural systems.

On sunny days, this trellis will cast shadows on the walls and floor of the courtyard. Projecting exactly where those shadows fall would have been difficult and tedious to do by hand. Because the software includes a function that positions the solar light source and casts shadows through the modeled trellis, it is simple to generate a series of perspectives that show, for various times of the day and year, exactly where the filigree pattern will fall.

"Without the modeling," Ericson says, "we would not have been able to accurately study the moving mural of light and shadow on the courtyard surfaces and understand the resulting spatial qualities. These studies helped us understand exactly how much surface decoration we would need and to what extent we could let the sun do the decorating." The study of light thus became as much a design criterion as the structure's geometry.

Beyond design

The implications of these expanding design capabilities are reaching beyond architectural studies and client presentations into construction processes. In an interview last year, Architectural Record editor-in-chief Robert Ivy asked Frank Gehry if computers had changed the way he thinks. Although he appreciates that his younger-generation employees can work back and forth between physical and digital models, Gehry confesses that he hasn't done that himself. Still, he insists that building the Guggenheim Museum at Bilbao would have been prohibitively expensive without the technology. By entering a mathematical model of the building directly into the fabrication equipment, the architects "de-mystified" the shapes for the subcontractors, so the steel bids came in on budget. Gehry says: "This leads to a new way to practice where the architect gains more control. So, the computer is a tool that can change architectural practice."

But is the tool changing modern architecture? Ellerbe Becket's Kyun Kim is not sure if form is the chicken or the egg; whether, he says, "the design palette encouraged us to develop computer skills or whether the computer's abilities brought curvilinear shapes to the palette. But clearly we're now able to demonstrate our design notions about this wonderful free motion, which would have been impossible in the past. Drawn by hand, such forms would have been out of proportion and inaccurate, and would not have conveyed the design message to the client."

B.J. Novitski is managing editor for ArchitectureWeek and author of Rendering Real and Imagined Buildings.

This article first appeared in Architectural Record, June, 1999.

Each 75-meter-long band, supported along one edge by concrete pylons, cantilevers 52 meters over the stadium seats. Image: Ellerbe Becket Curved surfaces and circular openings suggest a nautical motif in a stateroom of the underwater habitat designed by WAT&G. Calculating their precise intersections required the Boolean operations of a computer modeler. Image: Wimberly Allison Tong & Goo The underwater portion of WAT&G's proposed U-SEA Habitat is circular in plan to resist high pressure. Image: Wimberly Allison Tong & Goo The above-water structure of the U-SEA Habitat is polygonal in plan and pyramidal in section. Image: Wimberly Allison Tong & Goo The deceptively simple skylight designed for an atrium at Boston College was hand-rendered over a computer-generated underlay. Image: Shepley, Bulfinch, Richardson and Abbott An irregular-shaped courtyard was formed by a new building sited adjacent to an existing boomerang-shaped building at Boston College. Image: Shepley, Bulfinch, Richardson and Abbott   Click on thumbnail images to view full-size pictures.