Bending-Active Formwork Systems for Concrete Shells and Vaulted Floors
EMBARGOED UNTIL 2026-12-09
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Date
2025
Publication Type
Doctoral Thesis
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yes
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EMBARGOED UNTIL 2026-12-09
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Abstract
The construction industry faces increasing pressure to reduce embodied carbon, with reinforced concrete structures, particularly floor systems, responsible for a major share of global material use and emissions. While funicular shells offer structurally efficient alternatives, their adoption is often limited by the complexity, cost, waste, and reliance on high-tech fabrication associated with bespoke formwork. This dissertation investigates how bending-active formwork systems can be designed, engineered, and fabricated to enable the in-situ construction of efficient concrete shells and vaulted floors using material-efficient methods and readily accessible technologies.
The research addresses key challenges related to active bending, including geometric control, structural robustness, and fabrication efficiency at architectural scale. Two novel complementary systems are developed: (1) a double-layered spline gridshell that combines falsework as integrated reinforcement, and (2) a reusable, corrugated plate formwork based on a curved-crease unfolding (CCU) mechanism. Both strategies use structural geometry with the double layer and curved-crease folds as a core design driver to enable geometric control for the precise shaping of funicular structures, embed stiffness to support the wet concrete, and propagate structural articulation into the resulting concrete shells.
This research follows an integrative co-design methodology supported by a computational design-to-fabrication workflow, which enables form-finding, sensitivity analysis, and fabrication-aware modelling to be interwoven throughout the development process. A catalogue of opportunities frames the design space for bending-active formwork systems. The curved-crease unfolding (CCU) method is introduced as a novel approach, evolving from curved-crease folding for compact-to-spatial accordion-like or fan-like deployment. Its formulation is grounded in discrete differential geometry and expressed through design rules that enable exploration of the design space. System-specific form-finding procedures demonstrate geometric control, while finite element simulations assess stiffening strategies and scalability. Materialisation is addressed through a mono-material approach for the spline gridshell and textile-based hinges for the CCU system. Both systems are validated through full- and half-scale prototypes, evaluated for shaping accuracy, logistical efficiency, material use, cost, and construction time.
The spline gridshell with textile shuttering enables ribbed skeleton shells with integrated reinforcement, while the reusable CCU system enables unreinforced fan-vaulted floors. Both rely on straightforward prefabrication, flat-packed transport, and rapid in-situ assembly or unfolding. Their applicability ranges across various spans and parallel vaults, synclastic, anticlastic, and fan-like geometries. Expressive tectonics emerge through structural articulation shaped by the constraints of structure and fabrication. By employing structural geometry for both formwork and the resulting shell floor, these systems significantly reduce formwork waste, material use, cost, concrete and steel mass, and reliance on bespoke digital fabrication. They thereby aim to make structurally efficient non-standard geometries viable beyond elite applications and contribute to more sustainable construction.
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published
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Examiner : Block, Philippe
Examiner : Knippers, Jan
Examiner : Van Mele, Tom
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ETH Zurich
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Subject
Bending-active formworks; Active bending; Formwork; Flexible formwork; Concrete shells; Unreinforced vaulted floor; Curved-crease folding; Curved-crease unfolding; Bending-active plates; Bending-active gridshells; Stay-in-place formwork; Integrated formwork; Deployable formwork; In-situ construction
Organisational unit
03847 - Block, Philippe / Block, Philippe