Probabilistic-based discrete model for the seismic fragility assessment of masonry structures

Classical Finite-Element and Discrete-Element strategies are expensive to carry when analysing masonry structures in the inelastic range, under a seismic excitation, and considering uncertainty. Their application to the seismic fragility assessment of masonry structures through non-linear time-history analysis becomes thus a challenge. The paper addresses such difficulty by presenting an alternative probabilistic-based numerical strategy. The strategy couples a discrete macro-element model at a structural-scale with a homogenization model at a meso-scale. A probabilistic nature is guaranteed through a forward propagation of uncertainty through loading, material, mechanical, and geometrical parameters. An incremental dynamic analysis is adopted, in which several assumptions decrease the required computational time-costs. A random mechanical response of masonry is provided by numerical homogenization, using Latin hypercube sampling with a non-identity correlation matrix, and only a reduced number of representative random samples are transferred to the macro-scale. The approach was applied to the seismic fragility assessment of an English-bond masonry mock-up. Its effectiveness was demonstrated, and its computational attractiveness highlighted. Results may foster its use within the seismic fragility assessment of larger structures, and the opportunity to better analyze the effect of material and geometric-based uncertainties in the stochastic dynamic response of masonry structures.