CATIA at Frank O. Gehry & Associates, Inc.

"This technology provides a way for me to get closer to the craft. In the past, there were many layers between my rough sketch and the final building, and the feeling of the design could get lost before it reached the craftsman. It feels like I've been speaking a foreign language, and now, all of a sudden, the craftsman understands me. In this case, the computer is not dehumanizing; it's an interpreter." Frank Gehry

Introduction to FOG/A

Located in Santa Monica, California, the architecture studio has a staff of over 60 professionals and includes extensive model-making facilities and a model building staff capable of executing everything from scale architectural models to full size mock-ups. The facilities include a complete materials library containing materials samples and research documentation. FOG/A employs a network of sophisticated Computer Aided Design workstations in the development of FOG/A's work and the translation of these designs into design and technical documents. The firm has implemented CATIA which is supplemented by more traditional architectural CAD programs.

At the heart of the firms approach to design is a process which Frank Gehry has developed over the last three decades. In this process the client and the end user are brought fully into the design process as members of the design team, exploring their attitudes and goals in a way that makes the design a true collaboration between the designer and client. The design process is based on intensive modeling at multiple scales. These models explore both the functional and sculptural aspects of the project in a medium understood by designers and laymen alike. Very early in the process, building materials and mock-ups at full scale are employed to enhance the development and understanding of the design as architecture. Working simultaneously with materials and systems at the detail level and the formal image at the urban scale, the work evolves in response to the programmatic and budgetary goals defined by the client. It is the process of integrating the clients and users goals within the urban and cultural context of the project that gives each of Frank Gehry's projects the range, variety and individuality for which he is famous.

Frank Gehry has a particular interest in the use of materials in construction and a long standing respect for the craft of building. This has lead the firm to establish working relationships with the building tradesmen and fabricators nationally and internationally. These relationships have allowed the firm to explore unique applications of materials and systems in its projects, bringing the craft of building into play in the design. This combination of model building and mock-up capabilities, materials research and building technology and the application of advanced computer systems places Frank O. Gehry & Associates, Inc. at the forefront of architectural technology.

Selection of CATIA Software

One of the main obstacles between Gehry's design concepts and their construction was the act of documenting three-dimensional shapes with two-dimensional drawings. Gehry's staff would carefully measure his hand-crafted models, perform lengthy calculations, and prepare multiple sections and plan cuts to try to describe the design. Unfortunately, such drawings are time- consuming, costly and tended to make the shape seem more complex than it actually was. Contractors, uncertain about how the unusual forms could actually be built, would err in their cost estimates. That would lead Gehry, concerned about staying within the client's budget, to compromise his design. So in 1990, Gehry's staff began seeking computer software that could handle the complex 3D models yet leave intact Gehry's physical-model- based design process.

During this search, the firm tested a variety of architectural software. The architects' first experiment built with computers was the large fish sculpture for the Barcelona waterfront in the 1992 Olympic Village. The sculpture, about 180 feet long and 115 feet tall, is characterized by complex curves that defy traditional two-dimensional documentation. Initially modeled in wood and metal, its curvilinear surface is clad in flat, woven, stainless steel panels that float above an exposed steel structure. Facing severe time constraints, the architects explored computer technology as a medium to communicate their design to the builders. A surface model of the fish was produced using Alias software and although this representation was visually accurate, the software at that time proved limited. Like most architectural and rendering software, Alias defined the fish surface as a grid of polygons.

By contrast, software such as CATIA with complete numerical control could define surfaces utilizing descriptive geometrical mathematical formulas that could be applied by steel fabricators to build the sculpture. Thus, an architect or builder could query a CATIA model for the precise location of any point on any surface. When this process was successfully demonstrated the builder, Permasteelisa, purchased a seat of CATIA. The architects created a CATIA model of the Barcelona fish, then tested the model's accuracy by constructing a paper model with a numerical controlled three-dimensional laser-cutter directly from the computer model. With a few modifications, Gehry verified that this new model matched his original conception.

Construction of the final sculpture followed with astonishing speed and accuracy. From preliminary design to the completion of construction required only about six months. Of the thousands of connections two were off by 3 millimeters and the rest were perfect. And there were few traditional drafted construction documents or shop drawings. "Flat drawings of curved surfaces can be beautiful," Gehry admits, "but they are deceptive. With this system, you can see how to build it." The fish sculpture convinced Gehry and his associates that CATIA model data could be invaluable in helping to fabricate complex forms quickly and accurately.

The use of CATIA in FOG/A Projects

A bus stop in Hanover, Germany extended the capabilities developed for the Barcelona fish. The bus stop's shallow arching vault of silver and green stainless steel is supported by a dense grouping of vertical steel "T" shapes. Both the canopy and structure were modeled in CATIA and used to create design documentation. A distinct advantage came about when using CATIA on the bus stop project when it went out for bid. The winner, Permasteelisa's bid was one-third lower since they knew that they would be receiving CATIA data.

In further exploring the possibilities of using CATIA the firm's next test was in the limestone cladding for the 200,000 square foot Disney Concert Hall in Los Angeles. The stone cladding has been developed using CATIA for both design and cost control. Using the thickness of raw block of stone and cutting time as prime drivers of cost, it is easy to understand that cost increases in direct relation to the geometric progression from flat surfaces through to single, double and complex curvature surfaces. Gehry began design by building a paper model characterized by irregular, flower-like curves. The design model was then digitized using a Firefly optical digitizing system and the resulting x, y, z coordinates were feed into an IBM RISC/6000 running CATIA. The surfaces were then rationalized in CATIA to achieve repetition without sacrificing form. Using the CATIA database of the rationalized surface models, a physical model was computer milled, compared to the original cardboard model and adjusted where necessary.

The CATIA database, which has also been used to generate construction documentation, was subsequently passed on to the stone subcontractor. The stone cladding and cladding support package was tendered to 14 firms with three-axis and five-axis milling capability. As part of their submission, four were required to build a 3x8 meter piece of wall using only numerically controlled computer milling. The selected subcontractor, Harmon Contract with Furrer Spa of Carropuo, Italy was on budget. Both Harmon and Furrer intend to use their own CATIA stations to execute the project when it proceeds.

The advantages of using CATIA have not been unique to the Disney project. FOG/A took the use of CATIA on the Prague office building to another level. It was the first time that the entire building was done as a 3D computer model at FOG/A. In addition, it was done primarily using solid elements in conjunction with surface elements, another first for the office staff. The project itself further explored complex curved sculptural design in pre-cast concrete, steel and glass. Using the CATIA database together with other CAD tools, the staff has been able to model the unique glass and metal systems to a shop drawing level making fabrication and layout feasible. The initial budget for the glazing package was $200 per square foot. With the help of CATIA models to detail fabrication and layout, Gehry is working closely with the subcontractor, to reduce the cost by one-third to $135 per square foot.

More recently, FOG/A has used the benefits of CATIA in designing the Guggenhiem Museum in Bilbao, Spain. Using CATIA to completely define the complex sculptural surfaces of the 24,000 square meter facility was essential for the firm to meet the aggressive fast-track schedule required by the project. Using lessons learned in the Barcelona Fish, Hanover Bus Stop, Disney Concert Hall and Prague projects FOG/A integrated the application of advanced 3D CATIA models to construction and fabrication with the production of more traditional construction documents in AutoCAD. As in previous projects, the 3D CATIA surface model acted as the master model for dimensional control. The AutoCAD models were derived from CATIA geometry that was translated to AutoCAD using IGES through an in-house derived process. A complex integration of CATIA and AutoCAD had to be implemented in order to facilitate the design process and to satisfy the need for quality construction documents.

Once each of the distinct pieces of the building were completed in CATIA, the CATIA model containing face and surface elements was sent out to a machine shop. A scale model was NC milled directly from the CATIA data using a foam material. Each piece was then positioned to create a complete computer verification model to confirm the design to the project team.

FOG/A Local Area Network Configuration

In a very short time the firm's investment in computer technology has lead to a very sophisticated and diverse set of software and hardware tools. The range of tools cover the spectrum from PCs for word processing to a Sun Sparcstation 20 server complete with Internet access. Due mostly to the unique process that FOG/A has developed a suite of CAD and supporting software tools are used. There is, of course, a heavy reliance on IGES translators to transfer computer data between the various platforms and specific processes have been developed at the firm to handle the unique idiosyncrasies of each platform.

The suite of hardware platforms includes four IBM RISC System 6000 workstations installed with CATIA Version 4 modules:

• Advanced Detail Design
• Free Form Design
• Publishing Package
• Interface
• Develop

Summary

FOG/A's use of CATIA has led to closer relationships with contractors and direct relationships with suppliers and subcontractors. By generating the CATIA database to which everyone works, the practice increases its responsibility. The hope is that the accuracy of the information and the elimination of middlemen reduces everyone's cost and risk, and make the schemes more buildable. However, notwithstanding the high degree of accuracy of CATIA models and computer generated construction documentation, the achievable tolerances for both fabrication and erection which are inherent in the materials used remains largely unchanged, and FOG/A is conscious that this must be kept in mind continuously when working with computer models.

Fortunately, this technology that may bolster architects' position in the industry promises to encourage creativity. By translating complex design through CATIA, Gehry believes that curved forms in building will become more feasible. "I'm excited about them because I like to sense of movement. They feel genuine, accessible, joyful. If I do a lot of buildings with curves, and people enjoy them, then clients will begin demanding them, and more architects may follow."

Using the CATIA program allows Gehry to think big. He still starts a project by sketching and manipulating physical models. But when his design is put into the computer using CATIA with its precise replication of his sculptural and arrhythmic surfaces means contractors can estimate the cost - and can see how to build his elaborate designs. "I was doing this stuff anyway," says Gehry, "but I feel more confident that we can build it. It demystifies it."