How to form find shells that withstand earthquakes? We asked Tim Michiels who was just awarded the prestigious Hangai Prize.

Yesterday our PhD Candidate Tim Michiels was awarded the Hangai prize for his “Outstanding paper by a young talented researcher under 30”  at the annual symposium of the International Association of Shell and Spatial Structures (IASS) in Hamburg. Tim presented his research titled “Parametric study of masonry shells form found for seismic loading”  during the plenary session on Tuesday. Tim’s award marks the 3rd consecutive  prize for the Form Finding Lab at the yearly IASS conference, after Edward Segal et al.’s Tsuboi prize in Amsterdam (2015) and the stadium competition won by Olek Niewiarowski in Tokyo (2016) last year.

 

Tim’s research was co-authored by Prof. Adriaenssens and Prof. Jorquera-Lucerga of the Universidad Politécnica de Cartagena. It presents a form finding approach that allows for the shape generation of masonry shells in seismic areas. There is a renewed interest in constructing these masonry shells because of their low carbon impact, spurring the need to understand how such shells should be designed in seismic areas. Earthquakes are expected to have an important impact on the behavior and thus the shape of these medium-sized shell structures, as their large horizontal forces induce large bending moments that cannot be accommodated in thin, zero-tensile strength shells. Nevertheless, currently available form finding techniques for shells, rely solely on gravity loads for the generation of their shape and do not account for seismic loading.

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Examples of two recently constructed masonry vaults. Left: residential house in Oaxaca by Ramon Aguirre Morales (Image credit: Ramon Aguirre Morales). Right: Venice biennale droneport project by Odb, Block Research Group, Norman Foster Foundation and Redline (Image credit: Michiels)

Therefore, the masonry shells are form-found for both vertical gravity and horizontal seismic loading so that a compression-only load path exists within the thickness of the shell. Through the application of an inverted hanging net model subjected to lateral loading in a dynamic relaxation solver, shell forms are generated for which it can be ensured that such a load path exists. It is suggested to implement the obtained forms as interconnected double-layer thin shells, so that an equilibrium thrust surface can form over a wide depth of the structure, while maintaining the construction advantages of thin-tile vaults.

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World map overlaying seismic risk and locations with tradition of earthen construction (Image: Michiels et al., 2017).

The shapes discussed in this paper are the first instances of compression-only shells reported in literature, whose forms are successful and efficient in withstanding combined gravity/seismic loading.  The research demonstrates how to tailor masonry shells for a resilient built environment and can be extended to the shape generation of shells constructed out of other compression-only materials such as unreinforced concrete, stone and earth. The full paper will be published in the upcoming issue of the Journal of the IASS.

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Initial shapes for double layer shells based on a rectangular grid (Image: Michiels et al. , 2017)
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