How could a structure as important as Baltimore’s Francis Scott Key Bridge collapse “like a house of cards” when hit by a boat?
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The structure on which an average of 11.5 million vehicles travel annually collapsed during the night from Monday to Tuesday after a boat collided with one of its pillars.
In an interview with LCN, the engineer and founding president of Soconex, Normand Tétreault explains that it is a cantilever bridge with an arched metal structure which rests mainly on two pillars “relatively distant in this this case.”
“With the fact that it is arched, all the loads arrive on the famous two large pillars, and unfortunately, the boat hit one of these two pillars and therefore (…) it looks like a house of cards and everything is falling apart.”
“What you have to think about is that a boat of this size has enormous inertia and there are no brakes on a boat,” he continues.
The expert, however, expresses doubts about the protection installed around these nerve points.
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“What I find a little unusual is that there is enough water to transport a large boat like that, but I don’t find that there was very much protection around the pillars,” he says. -he. This is the heart of what supports the bridge.”
One of the first collapses of the Quebec bridge, which is of the same type as that of Baltimore, was also due to too much pressure applied to a pillar, the engineers having incorrectly calculated the required resistance.
“What you need to understand is that when a bridge is built, it needs greater strength than once it is built,” he maintains. When it’s tied together, it behaves well and when it’s not tied together, you build in a vacuum and if there’s not enough strength in the middle, it collapses.”
According to the expert, it is unlikely that a situation of this kind would occur in Quebec.
“If I look at the Champlain Bridge, the pillars that support it are outside the seaway,” he said. In other words, for a boat to get there, it will have to break through the ground or the dikes on each side. Boats of that tonnage cannot even go beyond the Jacques-Cartier Bridge.”
“Trois-Rivières is a bit shaped like that bridge, but the pillars are in shallow water, the boat would probably run aground before getting there,” he adds.
Watch the full interview in the video above
