Thrust Network Analysis for Masonry Assessment

Abstract

This chapter presents Thrust Network Analysis (TNA), a lower-bound limit-analysis-based method to assess vaulted masonry structures. With TNA, admissible equilibrium states corresponding to compressive force networks within the structural geometry can be studied. A novel multi-objective optimisation framework is described, which enables finding particular admissible equilibrium solutions in 3D structures subjected to general loading and support displacements. The equilibrium solutions searched include the minimum and maximum horizontal thrust states, the minimum vault thickness, maximum vertical and horizontal collapse loads, and compatible internal stress states following support movements. A complete picture of the structure’s stability level is obtained by combining these states, and the location where cracks arise at limit states is also highlighted. The method can be applied based on the surveyed geometric data of the structure’s envelope, being well-suitable for practical engineering problems. Analysis of shallow cross vaults and a surveyed cathedral demonstrate the method’s applicability and its relevance to assessing vaulted masonry structures.