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Engineer Says Notre-Dame Is Vulnerable to High Winds

Models show damage to the roof vaults have cut the structure’s wind resistance by over half

(Photo by Chesnot/Getty Images)
smithsonian.com

After the catastrophic fire that gutted Notre-Dame Cathedral in Paris last month, it seemed like the iconic Gothic structure was safely on the path to reconstruction. But a new engineering analysis says the cathedral is still in danger, and that winds over 55 miles per hour could cause part of the structure to crumble.

TheLocal.Fr reports that mechanical engineer Paolo Vannucci from the University of Versailles, who spearheaded a fire-risk report for the cathedral in 2016, is most concerned about the stonework on the vaulted roof that partially collapsed. Without all of its interconnected parts, he says, the structure has lost a significant amount of wind resistance. Before the fire, it was estimated the church could withstand winds up to 137 miles per hour. Now, after running simulations of the damaged cathedral, Vannucci estimates it could only withstand half that.

Architect Francesco Bandarin, writing for The Art Newspaper, reports that the nature of the Gothic architecture means that without the roof, the structure is now inherently unstable. Previously, the rib vaults, ceiling and flying buttresses all worked together as a unitary system to stabilize the building. Without the roof in place, more reinforcement is necessary to shore up the walls.

The wind is not the only threat to the cathedral. Christophe Villemain, historic restoration specialist, told French television station BFMTV that rain could cause more of the roof to collapse as well. “The rain risks falling on the vaulted ceiling and filling up what we call its haunches, or hollow sections, and that would put the arches at risk of collapse,” he says.

Earlier this week, as rainstorms appeared on the horizon, climbers secured temporary covers on the cathedral to keep water from getting in. When restoration work begins, there are plans to put in place a sturdier semi-permanent “umbrella” to protect the structure from the elements.

While Paris is not located on the regular path of hurricanes or tropical storms, it doesn’t take a hurricane or tornado to produce winds above 55 miles per hour. In January 2018, for example, winter storm Eleanor brought winds over 100 miles per hour.

Bandarin reports that France is moving along with restoration as quickly as they can. Next Monday, the French senate is expected to pass special legislation that will create a public agency to oversee the necessary work on Notre-Dame.

When the cathedral is rebuilt, it probably won't resemble the medieval structure it once was. The 1860 spire that collapsed will be replaced by something new. And an architectural competition to design a new roof for the church has already generated a lot of ideas, including solar-panels, a roof garden, a glass-and-steel structure, a completely stained-glass roof and even spires that shoot light into the night sky.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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