Computing and knitting: experiments on tailoring concrete and knitted textile for shell structures

This thesis proposes an integrated design and production approach to seek future construction scenarios for the complex concrete thin shell structures by utilising material behaviour and computational tools. The investigations focus on the findings and the outcomes of the composite usage of concrete (as a compressive material) and knitted textile (as a tensile material). Motivated by the feasibility problems of complex concrete shells, the potentiality of initially delicate and flexible materials are explored to generate structurally efficient lightweight concrete shells in order to eliminate the need for formwork, minimize the production cost and time by promising less labor-intensive, more sustainable and waste-free structures. The thesis is conceived in two parts with five chapters. The first part, comprising of chapter 2 and 3, is concerned with the context and methodology of the study that has been triggering the generation of this research. The second part presents the experiments both in digital and physical environment related to the tailoring knitting and concrete and comprises chapter 4 and chapter 5. In chapter 2, a brief history related to the concrete thin shell structures and the changing role of textile in these structures are provided in the context of form studies and constructability limitations. The reawaken tendency to explore possibilities on concrete shells, which was almost disappeared due to the feasibility problems related to the formwork limitations, is addressed through continuously developing digital design and fabrication tools. The developments that have threshold characteristics on concrete shell structures are emphasized while discussing the realised examples from the early 1900s until today. The chapter is concluded by drawing attention to the differences between the current examples, which use textile as molds and/or reinforcement, and the developed approach in this thesis, in response to the constructability problems of complex forms with concrete. In chapter 3, the relationship between structure, form and material in shell structures is elaborated. To support the outlined discussion, integrated systems with computational aspects are investigated. The lightweight character of the structure is interpreted through the material and the mechanical behaviour of the material is coincided with the microstructure of the material, in an attempt to minimize possible cracks and maximising adhesion. In parallel, the effects of the mechanical behaviour and correspondingly the internal structure of the material on the enhancement of the structural behaviour of the system are explored to establish a methodological framework for experiments. In chapter 4, series of structured material experiments on the composite usage of concrete and knitted textile are presented, where the integration of material feedbacks from physical models and the structural feedbacks from digital model was provided, in order to achieve the feasible form alternatives. The investigation on material combines both microscale and macroscale analysis, not only to get a deep understanding about the material properties and limitations but also to determine optimum cement mixture to obtain maximum mechanic behaviour from the material. Finally, chapter 5 gives concluding remarks and touch open the possibilities of enhancement for the findings of this research and discuss the potential evolving scenarios for future studies. The constraints encountered throughout the whole experimental process are also discussed in detail. The outcomes of the study can yield for further understanding on complex nature of concrete shell structures in the context of form, material and structural behaviour to minimize the production cost, time and promise more sustainable structures by releasing almost waste-free production process. The method used for this study can be evolved into a new series of structures in other scales with various materials, tools and different knitting techniques or produced prototypes can be evolved into components of an adaptive full-scale shell system in the future studies.