Image: Notre-Dame de Paris composite transverse section

Description: Composite transverse section of Notre-Dame de Paris before the 2019 fire. Timber framework in red, masonry in blues, metal in grey. Left, a tower, showing internal framework of belfry (bells not shown). Center, nave, covered by masonry vault and 55-degree triangular roof (spire shown above and behind). Right, side aisles, triforium aisle above, flying buttresses. Note that the vaults thrust outwards on the walls, and the flying buttresses thrust inwards; unless these two forces balance, the wall will be pushed over. Black arrows show the force of the weight of the structure being transmitted to the ground; green arrows show the upwards force of the ground supporting the structure. Orange and grey arrows show the forces in the wood and metal of the roof trusses. Roof trusses cancel out their outwards forces using internal tension (masonry cannot support tension). Light added for clarity.
Title: Notre-Dame de Paris composite transverse section
Credit: Own work, derived as indicated under "authors"
Author: Own work, traced from public domain File:Notre Dame 531 transverse crop rot.jpg and heavily altered, mostly using the public domain architectural drawings of Eugène Viollet-le-Duc (see particularly Category:Frame of Notre-Dame de Paris). The public-domain image File:Materials and documents of architecture and sculpture - classified alphabetically (1915) (14587788087).jpg was used for the stair. Photos were also used to verify details; thanks to all Commons contributors who took unconventional shots.
Usage Terms: Creative Commons Attribution-Share Alike 4.0
License: CC BY-SA 4.0
License Link: https://creativecommons.org/licenses/by-sa/4.0
Attribution Required?: Yes