Validating the Use of Graphical Thrust Line Analysis for Pier Buttresses: The Case Study of Amiens Cathedral

Abstract

Modern computational resources provide important and efficient tools for analyzing structures of all scales, materials, and typologies, especially historic structures. However, not all methods can correctly answer questions about the structural behavior of inherently discontinuous unreinforced masonry constructions. Such continuous methods, photoelasticity and finite element methods, are pervasively and incorrectly used to analyze masonry structures despite the availability of more appropriate methods. This article addresses the use of these different analyses by comparing the different results of two previous continuous model studies of the pier buttresses of Amiens Cathedral to new results using two discontinuous methods, discrete element methods, and graphical thrust line analysis. This case study validates the use of graphical thrust line analysis and challenges the use of continuous models in analyzing historic masonry constructions. Furthermore, these results resolve a longstanding debate about the placement of pinnacles while providing evidence that the analysis method must reflect physical behavior.