EIGHT centuries on, the flying buttresses of Bourges Cathedral in France still beguile engineers. The secrets behind this marvel of medieval masonry are now about to be laid bare, thanks to a group of researchers who are rebuilding it, brick by brick.
Using a laser scan of the cathedral, a team led by John Ochsendorf of the Massachusetts Institute of Technology have 3D-printed thousands of bricks and are building an exact 1:50 replica. The researchers hope to use the mock-up to devise a way to gauge the stability, and thus safety, of historical buildings built of brick and stone.
Modern buildings are usually constructed around a steel framework. The steel pieces are fused, so under stress from a sinking foundation or an earthquake, say, the framework behaves as a cohesive unit.
Advertisement
Masonry structures are much more complex. Removing a single brick can change the pattern of stresses throughout the building. This makes it difficult to capture the forces at play, says Mathew Bronski, a structural engineer at architecture firm SGH in Boston. Computer models and simulations help, but there are a lot of inherent shortcomings, he says.
鈥淧eople have been drawing buildings forever, but they鈥檝e often been making up the building as they go because they can鈥檛 measure it,鈥� says team member Andrew Tallon at Vassar College in Poughkeepsie, New York. 鈥淲ith a laser, you can get into places that you couldn鈥檛 hope to reach without three months of scaffolding and shutting down the cathedral you鈥檙e working on.鈥�
Building the replica is painstaking work, but Ochsendorf thinks the process itself may be as valuable as the mechanics uncovered. For students of architecture and structural engineering, hands-on experience has largely given way to computer modelling. Techniques like 3D printing could be a way of reconnecting them with the craft behind the science, he says.
鈥淯ntil now [structural engineering] has been dimensionless,鈥� says Ochsendorf. 鈥溾�楬ere鈥檚 a prototypical dome of this thickness and this span鈥� 鈥� but it wasn鈥檛 modelled off of any specific building.鈥� As 3D printing becomes ubiquitous, he says, learning could become less abstract and students will increasingly work from real-world examples.
聯As 3D printing becomes ubiquitous, students will increasingly work from real-world examples聰
This article appeared in print under the headline 鈥淗istory comes alive in 3D-printed bricks鈥�
