After the fire that devastated Notre-Dame de Paris ten days ago, the resistance of the structure of the cathedral to strong winds has significantly decreased, worried Paolo Vannucci, CNRS engineer and good connoisseur of the building , this Thursday.
"We measured a 60% decrease in wind resistance. The structure has changed. Part of this structure no longer exists, the roof has disappeared, as well as part of the vault. This collapse of part of the vault caused the greatest damage "to the balance of the Gothic building, said Paolo Vannucci, who said he used a digital model to perform simulations.
Resistance to winds of 90 km / h, against 222 km / h before
The engineer, who had done a report in 2016 on 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 it "is only 90 km / h today". He did not exclude that "a violent storm could in the current state lead to the collapse of part of the clair-étage", that is to say the upper row of the walls of the nave decorated with stained glass windows , while stressing that these are mere hypotheses as long as
the precise data are not precisely known about the state of the structure.
"Our Lady has really lost her ability to resist. The vaults were exposed to high temperatures, and the stones and mortars were damaged, "so that" the compressive strength has been reduced, "says the 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 out of water and drying.
Indoor and outdoor sheeting started on Tuesday.