A simplified procedure for assessing the seismic capacity of masonry arches

In this paper, a simplified procedure for assessing the seismic capacity of masonryarches is proposed. The algorithm couples two quite simple analysis approaches, i.e. FEM linear analysis and limit analysis applied following Heyman’s hypotheses to a pre-chosen failure mechanism. In particular, linear analysis is used for detecting tensile and compressive stress zones in the masonry element and for identifying a probable class of failure mechanisms for which the collapse multiplier is then calculated taking advantage of a standard parametric CAD program. The procedure is iterative, since within the selected mechanism class, the position of the hinges has to be varied in order to minimise, in the kinematic approach, the collapse multiplier. The proposed simplified procedure is then applied to three triumphal arches of Neapolitan churches, verifying the results against non-linear FEM analysis using smeared cracking approach as implemented in the computer software ABAQUS. The three case studies considered in the paper are actually quite different in geometry. As a consequence, the structural behaviour and lateral strength are also expected to be fairly different. Despite the different geometry and the quite scattered values of lateral strength, a similar mechanism is identified for the three structural schemes. Also, the values of the lateral strength become closer when the total vertical load W is used for normalisation. This non-dimensional strength capacity can be directly compared to the seismic coefficient (non-dimensional strength demand), so that the results herein obtained can be useful for an evaluation of the seismic safety level of single structural macro-elements and, if their proper combination can be derived, of the church it belongs to