Computer-aided design and manufacturing of complex-shaped concrete formwork

The research presented in this thesis challenges the appropriateness of existing, conventional forming practices in the building construction industry--both in situ or in prefabrication--for building concrete "freeforms," as they are characterized by impracticality and limitations in achieved geometric/formal quality. The author's theory proposes the application of alternative, non-traditional construction methods derived from the integration of information technology, in the form of Computer-Aided Design (CAD), Engineering (CAE) and Manufacturing (CAM), into the concrete tooling and placing process. This concept relies on a descriptive shape model of a physically non-existent building element which serves as a central database containing all the geometric data necessary to completely and accurately inform design development activities as well as the construction process. For this purpose, the thesis orients itself on existing, functioning models in manufacturing engineering and explores the broad spectrum of computer-aided manufacturing techniques applied in this industry. A two-phase, combined method study is applied to support the theory. Part I introduces the phenomenon of "complexity" in the architectural field, defines the goal of the thesis research and gives examples of complex shape. It also presents the two analyzed technologies: concrete tooling and automation technology. For both, it establishes terminology, classifications, gives insight into the state-of-the-art, and describes limitations. For concrete tooling it develops a set of quality criteria. Part II develops a theory in the form of a series of proposed "non-traditional" forming processes and concepts that are derived through a synthesis of state-of-the-art automation with current concrete forming and placing techniques, and describes them in varying depth, in both text and graphics, on the basis of their geometric versatility and their appropriateness for the proposed task. Emphasis is given to the newly emerging and most promising Solid Freeform Fabrication processes, and within this area, to laser-curing technology. The feasibility of using computer-aided formwork design, and computer-aided formwork fabrication in today's standard building practices is evaluated for this particular technology on the basis of case-studies. Performance in the categories of process, material, product, lead time and economy is analyzed over the complete tooling cycle and is compared to the performance of existing, conventional forming systems for steel, wood, plywood veneer and glassfiber reinforced plastic; values added to the construction process and/or to the formwork product through information technology are pointed out and become part of the evaluation. For this purpose, an analytical framework was developed for testing the performance of various Solid Freeform Fabrication processes as well as the "sensitivity," or the impact of various influencing processes and/or product parameters on lead time and economy. This tool allows us to make various suggestions for optimization as well as to formulate recommendations and guidelines for the implementation of this technology. The primary objective of this research is to offer architects and engineers unprecedented independence from planar, orthogonal building geometry, in the realization of design ideas and/or design requirements for concrete structures and/or their components. The interplay between process-oriented design and innovative implementation technology may ultimately lead to an architecture conceived on a different level of complexity, with an extended form-vocabulary and of high quality.