Collapse load of a masonry arch after actual displacements of the supports

In this work, the collapse load of a masonry arch subjected to an actual horizontal displacement of the supports is assessed, in the deformed configuration of the structure, by means of limit analysis theory. Masonry is modelled as a rigid in compression, no-tension material and avoiding the occurrence of sliding failures. A numerical tool, based on the approach of the kinematical theorem of the collapse state, is proposed for the collapse computation of circular arches subjected to dead loads and to incremental concentrated load applied at their crown. A parametric study has been carried out in order to develop a deeper understanding of the influence of the involved parameters. It is shown that the existence of a kinematically admissible collapse mechanism is correlated to a thickness/mean radius ratio dependent on the value of the actual horizontal displacement of the supports. In the paper, a relationship between these two last parameters is proposed.