Stabilithos: a numeric tool for general limit analysis of stone structures
Résumé
Limit analysis for stone structures has become very quick to solve, with conic optimization resolution schemes, and has already proven its effectiveness, thanks to the large range of results it can give while requiring very few mechanical assumptions (Heyman, Livesley, Gilbert…).
The aim of this research consists in an interactive tool, Stabilithos, implemented in the Rhinoceros modeling software, allowing the exploration of different types of limit analysis on any 2D or 3D blocks structures. Various choices of fracture mechanical hypotheses for the joints between stone blocks are possible: Heyman hypotheses (zero tensile strength, infinite compressive strength, infinite sliding resistance), but also finest criteria, implemented without any simplifying assumptions for 2D and 3D convex shaped joints, thanks to general conic optimization: finite compressive strength and/or finite sliding resistance with Coulomb criteria. The simulation results are given in graphical form directly in Rhinoceros : the internal forces acting on each interface between blocks, the normal constraints if the compression constraint has a finite strength, and the animation of kinematic failure mechanism.
Thanks to an interactive interface, the following limit analysis loading modes in any given direction are available: maximizing one or several forces applied on the structure (wind loads, for example), maximizing a support reaction (active and passive thrusts, for example), or maximizing a force field proportional to block’s self-weight and applied to the block’s gravity center (seismic horizontal action, for example). An automated computation module allows serial simulations to provide parametric mechanical analysis with numerical output data. Additionally, it is possible to automatically determine the static and geometric safety factors of any 2D or 3D stone structure in order to ensure and evaluate its stability under dead loads. The tool's possibilities are evaluated with application cases on gothic structures.