Reporting from IASS 2017 – Severe Conditions & Disasters

Last week at the IASS the Form Finding Lab was very involved in the session on severe conditions & disasters. The session was chaired by our own Sigrid Adriaenssens and close collaborator Prof. Ruy Marcelo Pauletti from the University of Sao Paulo, and many more collaborators presented their research.

The revue of familiar faces started with Eftychia Dichorou from the University of Cambridge. Dichorou presented her work co-authored by Matthew DeJong (Cambridge University) and Giorgia Giardina (University of Bath) on the finite element modelling to predict cracking and seismic collapse of a thin masonry shell structure. Dichorou presented a quick historical overview of tile vaulting after which she focused on the impact of earthquakes on these structures. To model the effect of earthquakes, she presented a parametric study of the Droneport Project which was built last year at the Venice Biennale. She demonstrated the importance of accurately quantifying material properties of the masonry, particularly to capture its post-peak behavior, and also pointed out the need to understand the impact of geometric imperfections.

Dichorou’s presentation was aptly followed by an application of tile vaulting in Istanbul. Indeed, Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan presented their recent construction project on the Seismic design, detailing and construction of the first Catalan Vault and Domes of Istanbul. They showed how the Guastavino vaults of New York inspired them to build new brick masonry vaults during the restoration of the Hatice and Fehime Sultan Palace near the crossing of the Bosporus. They strengthened the vaults to account for earthquake loading by adding steel rebar as well as a coil steel-mesh.

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Ahmet Topbas from the structural design firm Ateknik, together with Dogan Arslan showing the plans of the vaults .

Then the session shifted from masonry shells and earthquakes, to the modeling of cable net under other impact loads. Romain Boulaud from the Ecole Des Ponts ParisTech presented a sliding cable model for rockfall barrier simulations. He detailed the behavior of these flexible barriers, showing their strong nonlinear behavior (both geometric as material). These strong nonlinearities were accounted for in simulations relying on dynamic relaxation, which showed a robust, yet time-consuming solution.

Form Finding Lab PhD candidate Olek Niewiarowski then presented his Master’s thesis work on cable nets subjected to underwater loads, reminiscing about his brief tenure at Reunion Island to investigate nets used as barriers against shark attacks. Niewiarowski detailed his numerical model, and showed how the topology of nets can be impacted to better distribute the forces arising from the breaking waves.

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Olek Niewiarowski showing how to integrate breaking wave simulations.

Stefano Gabriele from the university of RomaTre got the final word and presented the work on the funicularity of shell structures he had elaborated with Giulia Tomasello (among others). Gabriele explained a new easy-to-read method to quantify whether a form-found shell structure works predominantly through membrane action, rather than through bending. The method hinges on the computation of the eccentricity (relating bending moment and normal force) in every point of the shell. The method was applied to modal stress distributions under different loading conditions, including earthquake loading.

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Prof. Gabriele explaining his new approach on how to evaluate how funicular shells are under applied loading.

The session was concluded by noting how surface structures such as shells, membranes and nets are particularly well suited to resist extreme loading.

Author: Tim Michiels