Digital Tectonical Demonstrations
A hybrid structure/ surface morphology emerges that produces lightweight systems of sinuous enclosure with potential to span structurally and carry integrated infrastructural components. The software is further used to produce analytical diagrams to measure degrees of curvature and concentrations of stress.
The scale of the spatial system and the degree of desired enclosure influence the material criteria. Components and connections are developed using computer-aided design and manufacturing (CAD/CAM) technology to produce customized modules that are embedded with the logics of assembly.
Complexity and Computation
In architectural simulation, information such as material constraints and site conditions can be fed into parametric computer models, returning feedback about the overall design. Simulation then becomes a way of assessing the performance of the project and the limits of a spatial system through a direct engagement with the basic geometry.
One of the objectives of our research is to go beyond using the digital model for aesthetic and tectonic assessment and to see it coupled with manual intervention and improvisation during construction.
A design/build project that followed this method was a fence installed at the Tulane School of Architecture. Its undulating surfaces combine a manageable complexity and anthropomorphic scale of assembly that enabled the students to use both computer-assisted fabrication and ad-hoc construction methods.
It was our desire to retain this spirit of improvisation and material feedback as we delved into more complex projections and explorations. The digital modeling techniques articulated this complexity so that links could be made between patterns, force, form, and site constraints.
One example of how software can demonstrate parametric adjustment is thermographic curvature analysis. Measuring the degree of curvature in a surface helps determine potential bending stress and material strain. This information is useful in determining ways to absorb and transfer forces — gravity, wind, etc. — through material responsiveness and component design.
A structure optimized for resistance to external forces can be further deformed in response to qualitative information such as use, scale and design intent.
With the Tulane fence, this form-making was expressed through a primitive fastening technique. The primary structural members are L-shaped steel tubes, but the connecting joints for flexible PVC pipe enabled students to customize the lattice curvature as informed by the CAD/CAM design and analysis techniques.
Bezier curvature models provided specific quantitative data of the PVC system. This information, coupled with a general understanding of the bending limitations of the PVC as a result of the section modulus, enabled the students to understand the range of configurations before they began crafting the fence sections. The digital model provided limits rather than specific joint placements.
A second project involved the design and fabrication of a lighting system at the University of Houston. Students designed small luminaires that were integrated into a larger-scale installation called "LiteBEAM," a repetitive, luminous, suspended ceiling system. Both the small objects and the large architectural framework were created with digital modeling, synthesis, and fabrication techniques in an interactive and cooperative environment.
Interactive computer simulations allow different potential realities to be tested and evaluated in advance of material implementation. When combined with fabrication, they give students a rare opportunity to experience construction directly.
In designing the luminaires, the students used parametric surface modeling to produce contours, patterns, and templates. They then worked with five fabrication techniques: casting/ molding, vacuum forming, 2D CNC cutting, 3D cutting/ sculpting, and folding/ bending.
The beams, the primary elements of the LiteBEAM suspended ceiling system, were conceived as sculpted solid forms, with complex shapes that were simple catenary expressions of a uniform load over a simple span. The 15-foot by 30-inch (4.6-meter by 76-centimeter) beams were sculpted in 2 axes by a CNC hotwire that is typically used to make architectural cornice shapes.
Between each beam is a series of vertical lenses, CNC router-cut from clear Plexiglas. These lenses are embedded with colored cold-cathode lighting and support a series of fluorescent single-tube fixtures that provide indirect lighting between each of the four beams.
Below the lenses and between each beam are a series of three shells — concave space frames that capture and diffuse the light emitted from the fluorescent tubes and the edges of the lenses. The shells are made of a series of 19 transverse profiles along a central spine with secondary longitudinal elements at the perimeter.
This assembly is wrapped with white stretch nylon. Each profile is CNC laser-cut from 1/8-inch (3.2-millimeter) steel plate, and fitted together with coordinated notches derived from the intersections in the digital model. A weld at each intersection makes it a semirigid frame, ready for the application of the translucent diaphragm skin.
The completed assembly hangs from a shop-fabricated, welded, and bolted connection to a cable suspension system. While this installation of the LiteBEAM system is made of four modules, it was designed as a repetitive system that could extend indefinitely.
With both the fence and the LiteBEAM projects, our goal is to use various modes of physical fabrication and computer modeling techniques to continue exploring surface morphology.
Combining design and fabrication facilitates the articulation of structural patterning and geometric mapping. Ultimately, we expect interactive computer simulations to become the means by which digital space and analog space can inform each other and produce a new tectonic.
Discuss this article in the Architecture Forum...
Brad Bell is assistant professor at Tulane University and principal of brad bell studio. Andrew Vrana is visiting assistant professor at the University of Houston and formerly worked with Renzo Piano Building Workshop and Miralles Tagliabue Architects. Joe Meppelink is a lecturer at the University of Houston and principal of Framework-AD.
This article was excerpted, with permission of the authors, from Digital Tectonics: Structural Patterning of Surface Morphology, published in the 2004 Proceedings of the Association for Computer Aided Design in Architecture.