Experiments to assess the risk of collapse
“The Gothic choir hall should be regarded as a ‘house of light’. Its pillars are extremely high to ensure that it would tower over the other buildings in the city, which by then had already grown”, explains Schindler. The Palatine Chapel was visible from afar thanks to its light and uncluttered interior. Furthermore, the high construction was what the master builders wanted; their aim at the time was to go ever “higher, faster and further”. This resulted in what Schindler describes as the cathedral effect. The 25-metre-long single-nave hall is dominated by its windows, which are around 26 metres high. “For a long time, it was not clear to what extent this kind of construction would risk collapsing”, says the architect. Incidentally, experts ask themselves this question with many Gothic buildings. The 2019 fire at Notre Dame in Paris in particular caused many structural engineers and cathedral researchers to spring into action. This shows just how topical this branch of research is.
Schindler has been studying the structural design of Aachen Cathedral since 2002. To this end, he spent more than ten years developing so-called extended chain models in a series of experiments. They are used by the scientists to draw conclusions about the stability of the building based on its constructional shape. An analogue simulation of the load transfer was performed in student seminars: “The building’s pillars can be simulated by a double chain. The first chain imitates the supporting structure and thus represents the exact distribution of the masses in the building. The second chain imitates the building’s shape and thus reveals the geometric architectural plan”, says Schindler. Fortunately, this showed that “the choir hall was obviously designed by its Gothic master builders in perfect equilibrium. Furthermore, the project provided us with a number of other nuanced insights into the load distribution of pillars and vaults”, explains the expert.
