3D Scanning and 3D Printing to Understand the Physics of Bourges Cathedral
So, you’re sitting in an ancient church, let’s say the Bourges Cathedral in France. You’re admiring the historical richness of the stained glass depicting the Last Judgment, the spandrels featuring tales from Genesis, and the high, high ceilings. All of a sudden, you think, “Man, this place is really old,” having been built in the 12th Century, “Is it going to collapse on me?” Sure, your friends might call you a hypochondriac, but there arelegit historians and architects who are worried about it, too.
A team of researchers at the Massachusetts Institute of Technology, led by John Ochsendorf, have scanned the entire cathedral and are in the process of building a 3D printed replica in order to understand just how tired those buttress might be after flying for eight centuries. Even modern buildings, with their steel frames, aren’t structurally sound, but, at least our skyscrapers behave as a single unit in the face of earthquakes or a sinking foundation. Brick buildings, such as the medieval cathedral, on the other hand, find their integrity in a family of bricks working together, according to Mathew Bronski, a structural engineer at architecture firm SGH in Boston. What happens to one brick can affect the stress throughout the entire building so that it’s even more complicated to understand how such buildings might behave in response to physical forces. By scanning and 3D printing the building in Bourges, however, Ochsendorf’s team can see how those bricks might behave under environmental pressures.
Andrew Tallon, a team member at Vassar College, explains how 3D scanning takes up where drafting and computer simulations fall off, “People have been drawing buildings forever, but they’ve often been making up the building as they go because they can’t measure it. With a laser, you can get into places that you couldn’t hope to reach without three months of scaffolding and shutting down the cathedral you’re working on.” And, at the same time that the 3D printed replica will aid in understanding the way the cathedral reacts to the forces around it, Oschendorf sees it as an opportunity to teach students hand’s on, saying, “Until now [structural engineering] has been dimensionless. ‘Here’s a prototypical dome of this thickness and this span’ – but it wasn’t modelled off of any specific building.”
We hope to see the 1:50 scale replica of the cathedral and hear about what the team was able to determine about how well those buttresses are flying soon. In the mean time, you can tour the Bourges Cathedral through Andrew Tallon’s panoramic photographs.