# Is there a name for a structure/building technique comprising three arches that share a central column? (Answer Found - Triple Arch System)

I saw a few minutes of a documentary that mentioned the domed roof of the largest mosque in Istanbul is supported by the strength of sets of three arches assembled so they share a common pillar. I'd like to learn more about that building technique but I'm not sure what the name is for that kind of structure. Also, can four stone arches share a central column or would the shared column likely collapse?

• Can you find a picture of what you mean (all the large mosques in Istanbul are extensivly documetned) you've seen what you mean while I have a hard time imaining the three arches. All the large mosques in Istanbul I've been to had floorplans of sqaures and rectangulars, don't know where three arches to one Pillar would show up.
– mart
Jun 13, 2017 at 20:17
• Thank you for your replies everyone - I managed to find the documentary on catch up tv (Cities of the Underworld Series 1 Episode 12), which was about Cappadocia, Turkey. They referred to it as a triple arch system'' with three arches placed at 0, 120 and 240 degrees that meet at a central column. Jun 14, 2017 at 7:17
• Do you just mean vaults? They are normally four-way (I've enver actually seenm three-way, but can't see any reason why it wouldn't work, but mankind normally buiolds rectangular buildings) See cdn.shopify.com/s/files/1/0569/5613/files/Vaucelles1.jpg or s-media-cache-ak0.pinimg.com/originals/65/11/11/… or look up 'groin vault' in wikipedia. Jun 18, 2017 at 19:52
• I suspect this was about Haga Sofia which has this arrangement Aug 19, 2019 at 20:28

The best answer I can think of is a form of “Flying Buttress” (FB).

A flying buttress is one half of a catenary arch. Therefore, the dome you reference would consist of six FB’s aligned in pairs. A FB receives upper end reaction supports from one or more support/supported structure(s). In the case of the Mosque, vertical reactions for all six FB’s are resisted by the column. It can be shown by simple vector analysis that horizontal reactions due to gravity cancel at the peak of the dome. A special connection detail is required at the top of the arches to facilitate horizontal force interaction & transfer. If our FB’s will also support the infill, the central column must support about the same gravity load regardless of the number of FB’s. Pictures of variations of Flying Buttresses are easy to find on the internet.