Notre-Dame: an expert worries about the resistance of the structure to storms

The resistance of the structure of the Notre-Dame cathedral to strong winds has significantly decreased since the fire that ravaged it ten days ago, worried Thursday Professor Paolo Vannucci, mechanical specialist and connoisseur of the building.

The balance of the structure threatened

"We have measured a 60% decrease in wind resistance, the structure has changed, part of this structure no longer exists, the roof has disappeared, and part of the vault has collapsed. from the vault caused the greatest damage "to the balance of the Gothic building," said Paolo Vannucci, who is professor of mechanics at the University of Versailles and explains having used a numerical model to carry out simulations.

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The cathedral would not withstand winds of more than 90 km / h

The engineer, who made a report in 2016 on the fire risks in Notre-Dame, calculates in the specialized magazine Batiactu that before the fire, "the speed of the critical winds that could support the cathedral was 222 km / hour "and that" is only 90 km / h today ". He did not exclude that "a violent storm could in the current state lead to the collapse of a part of the clear-floor", that is to say the upper row of the walls of the nave decorated with stained glass windows , while underlining that these are simple hypotheses as long as the precise data are not precisely known about the state of the structure.

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"Our Lady has really lost her ability to resist, the arches have been exposed to high temperatures, and the stones and mortars have been damaged," so that "the compressive strength has been reduced," says expert.

The fragilization of the monument must be evaluated from every angle by the experts before any work. Fire and water have had weakening and corrosive effects that can persist or manifest in the long term. One of the top priorities is putting the water out and drying. Indoor and outdoor sheeting started on Tuesday.