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Structural design, digital fabrication and construction of the cable-net and knitted formwork of the KnitCandela concrete shell

Popescu M., Rippmann M., Liew A., Reiter L., Flatt R.J., Van Mele T. and Block P.
Structures
2020
doi: 10.1016/j.istruc.2020.02.013

This paper describes the structural design, digital fabrication and construction of KnitCandela, a free-form, concrete waffle shell with KnitCrete, a falsework-less formwork approach using a custom prefabricated knitted textile as a multi-functional, structural shuttering layer and a form-found cable net as the main load-bearing formwork. The digitally designed and fabricated textile provided integrated features for inserting and guiding elements such as cables and inflatables that helped shape the sophisticated mould.

With a total weight of only 55kg, the 50m2 formwork was easy and compact to transport. On site, the formwork was tensioned into a timber and steel rig, the pockets were inflated and then coated with a thin layer of custom-developed, fast-setting cement paste. This paste served as a first stiffening layer for the textile, minimising the formwork’s deformations during further concrete application. Fibre-reinforced concrete was manually applied onto the formwork to realise a 3cm-thick shell with 4cm-deep rib stiffeners.

The novel approach, for the first time applied at architectural scale in this project, enables the building of bespoke, doubly-curved geometries in concrete, with a fast construction time and minimal waste, while also reducing the cost and labour of manufacturing complex parts.

BibTeX

@article{Popescu2020,
    author  = "Popescu, M. and Rippmann, M. and Liew, A. and Reiter, L. and Flatt, R.J. and Van Mele, T. and Block, P.",
    title   = "Structural design, digital fabrication and construction of the cable-net and knitted formwork of the KnitCandela concrete shell",
    journal = "Structures",
    year    = "2020",
    volume  = "",
    number  = "",
    pages   = "",
    month   = "",
    doi     = "10.1016/j.istruc.2020.02.013",
    note    = "in press",
}

Related publications

Popescu M., Rippmann M., Liew A., Van Mele T. and Block P.Concrete shell built using a cable-net and knitted formwork,DETAIL structure,1: 10-11,2019.
Popescu M., Reiter L., Liew A., Van Mele T., Flatt R.J. and Block P.Building in concrete with a knitted stay-in-place formwork: Prototype of a concrete shell bridge,Structures,14: 322-332,2018 (June).
Popescu M., Rippmann M., Van Mele T. and Block P.Automated generation of knit patterns for non-developable surfaces,Humanizing Digital Reality - Proceedings of the Design Modelling Symposium 2017,K. De Rycke et al. (editors),: 271-284,SpringerParis,2017 (September).
Popescu M., Rippmann M., Van Mele T. and Block P.Complex concrete casting: knitting stay-in-place fabric formwork,Proceedings of the International Association for Shell and Spatial Structures (IASS) Symposium 2016,Tokyo, Japan,2016.
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