FE Upper Bound Limit Analysis for Automatic Detection of Collapse Mechanisms in Masonry Buildings

A fast and robust finite element upper bound limit analysis method is introduced to estimate the spectral acceleration that triggers local failure mechanisms in historical masonry structures. Structural assessments are performed in compliance with the Italian building code, without assuming predefined failure mechanisms and considering masonry as a no-Tension material. The structural model consists of infinitely rigid hexahedral elements connected by quadrilateral interfaces that follow a Mohr-Coulomb failure criterion, where all plastic deformations are concentrated. The kinematic limit analysis problem is formulated in its standard form and solved using an established linear programming algorithm. Depending on the tensile strength, the collapse acceleration and the corresponding failure mechanism are determined automatically. Through an iterative extrapolation approach, the results for the no-Tension material model are obtained. Additionally, a novel filtering algorithm is introduced, which considers only the elements involved in the failure mechanism, enabling the estimation of the spectral acceleration leading to collapse. The methodology is applied to a portion of a complex historical building in northern Italy.