Rib-stiffened funicular floor system

This research develops the structure for an unreinforced concrete floor consisting of a thin funicular vault stiffened by a series of spandrel walls on its extrados. The structural prototype is completed with tension ties, which link the supports and absorb the horizontal thrusts of the funicular shell. It is a prototype for the NEST HiLo project to be realised in 2019 on the Empa campus in Dübendorf, Switzerland.

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The solution is inspired by built examples in tile vaulting in which thin vaults are stiffened by diaphragms, also called spandrel walls. In the present structure, this structural system is implemented and constructed in concrete to achieve an extreme thinness (2 cm in the case of this prototype for both vault and ribs) and to resist asymmetrical loading.

This floor would save more than 70% of the weight compared to traditional, 25-30cm-thick concrete floor slabs used in the construction of framed buildings. This directly lowers the requirements for the foundations (often a dominant resource and cost factor), but also enables lightweight building extensions and a reduction of total floor height, offering possibilities to address, among other issues, the vertical densification of cities.

A form-finding and analysis procedure for the design of such floor systems is presented, which consists of consecutive topology, shape, and size optimisations.

This research was featured in the Beyond Bending exhibtion at the Venice Architecture Biennale 2016. 

This floor will be implemented in HiLo: Research & Innovation Unit for NEST.


Block P., Van Mele T., Rippmann M., Ranaudo F., Calvo Barentin C. and Paulson N.Redefining Structural Art: Strategies, necessities and opportunities,The Structural Engineer,98(1): 66-72,2020 (January).
Liew A., López López D., Van Mele T. and Block P.Design, fabrication and testing of a prototype, thin-vaulted, unreinforced concrete floor,Engineering Structures,137: 323-335,2017.
Wu H., Liew A., Van Mele T. and Block P.Analysis and optimisation of a rib-stiffened vaulted floor for dynamic performance,Engineering Structures,213: 110577,2020.
Block P., Van Mele T., Rippmann M. and Paulson N.Beyond Bending - Reimagining Compression Shells,Edition DETAIL,Munich,2017 (October).
López López D., Veenendaal D., Akbarzadeh M. and Block P.Prototype of an ultra-thin, concrete vaulted floor system,Proceedings of the IASS-SLTE 2014 Symposium,Brasilia, Brazil,2014.


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