Capacity assessment of masonry arches on moving supports in large displacements: Numerical model and experimental validation

In the framework of rigid block analysis of masonry arches in large displacements, an innovative numerical procedure that estimates the collapse mechanism and the limit support movement is proposed, allowing the modelling of possible hinge change and therefore the evolution of the mechanism. Making use of combinatorial analysis, the position of the hinges at the onset of the settlement is found. Then, the admissible equilibrium condition is verified for any finite increase of the settlement and if the condition is violated, a new configuration of hinges inducing zero work increase is searched for. In this way mechanism evolution and hinge change are modeled as the support movement increases. The numerical procedure is employed to interpret both tests on pointed arches performed by the authors and tests on circular arches available in the literature. Broad sensitivity analyses to uncover the effect of thickness and embrace angle for circular arches and thickness and rise for pointed arches are also reported. Results show that hinge change can allow the arch to accommodate larger displacements. For vertical movements, only the central hinge changes position, while for the arch on spreading supports, the hinges at the haunches move although without significantly improving displacement capacity.