Flying buttresses at the Bourges Cathedral illuminated at night

The flying buttress, a masonry structure which uses an inclined bar carried on a half arch which extends or "flies" from the upper part of a wall to a pier to span a given distance, carries the thrust of a roof or vault. The flying buttress evolved in the Gothic era and was derived from simpler, and often hidden, support structures. More than any other architectural method, the flying buttress increased the supporting power of a buttress. The innovation of such ornamental buttresses led to the creation of the magnificent, soaring ceilings inside churches like the Bourges Cathedral in France.

Beguiling to engineers, the real secrets of medieval masonry are the subject of some intense scrutiny from a group of researchers using 3D printing to reconstruct – and deconstruct – the ancient techniques one brick at a time.

John Ochsendorf, the research lead for the project at the Massachusetts Institute of Technology, used laser scanning to capture the details of the cathedral's construction and he and his team then 3D printed thousands of bricks they're using to create a detailed replica of the Bourges Cathedral in 1:50 scale.

Back in 2009, Ochsendorf, a brilliant structural engineer, was studying bridge and infrastructure technology by fusing the new with old-world archeology. That work led to him receiving a John D. and Catherine T. MacArthur Foundation genius grant – to the tune of $500,000. Since then, he's spent his grant leading engineering students on an investigation of how the construction of 21st-century buildings might benefit from the lessons learned from medieval practitioners.

According to Ochsendorf, the team will use this mock-up to reveal the intricacies of historical buildings wrought from brick and stone.

Andrew Tallon 3D scanning the Bourges Cathedral

Masonry structures, with their high degree of complexity, are dependent on each brick or block for their stability and removing a single one radically changes stress patterns throughout a given structure. Team member Andrew Tallon, a professor of architecture at Vassar College, says that while computer simulation and modeling offers some insight into the inner workings of masonry structures, those methods lack critical details of which architects and designers need to further their understanding.

"People have been drawing buildings forever, but they've often been making up the building as they go because they can't measure it," Tallon says. "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."

While it's painstaking, detailed work, Ochsendorf says students of architecture and structural engineering will find the model an invaluable tool to reveal the mechanics involved in creating such classic buildings. Ochsendorf says 3D printing will act as a compliment to computer modeling to help connect students to the craft buried beneath the science.

"Structural engineering has been 'dimensionless,'" Ochsendorf said. "It wasn't modeled off of any specific building."

He added that 3D printing will help students learn from tactile examples and help remove a layer of abstraction from the process of understanding how buildings are actually constructed.