Masonry compression:: a numerical investigation at the meso-level

Purpose - To contribute for a reliable estimation of the compressive strength of unreinforced masonry from the properties of the constituents (units and mortar). Design/methodology/approach - Sophisticated non-linear continuum models, based on damage, plasticity, cracking or other formulation, are today standard in several finite element programs. The adequacy of such models to provide reliable estimates of masonry compressive strength, from the properties of the constituents, remains unresolved. The authors have shown recently that continuum models might significantly overestimate the prediction of the compressive strength. Hence, an alternative phenomenological approach developed in a discrete framework is proposed, based on attributing to masonry components a fictitious micro-structure composed of linear elastic particles separated by non-linear interface elements. The model is discussed in detail and a comparison with experimental results and numerical results using a standard continuum model is provided. Findings - Clear advantages in terms of compressive strength and peak strain prediction were found using the particle model when compared with standard continuum models. Moreover, compressive and tensile strength values provided by the model were found to be particle size- and particle distortion-independent for practical purposes. It is also noted that size-dependent responses were obtained and that shear parameters rather than tensile parameters were found to play a major role at the meso-level of the phenomenological model. Originality/value - This paper provides further insight into the compressive behaviour of quasi-brittle materials, with an emphasis on the strength prediction of masonry composites. Reliable prediction of masonry strength is of great use in the civil engineering field, allowing one to reduce experimental testing in expensive wallets and to avoid the usage of conservative empirical formulae.