Linear and non-linear FEM analyses to assess a shear flat-jack test for masonries

The shear properties are key characteristics for evaluating masonry elements under in-plane horizontal actions. Historical structures may need the evaluation of these properties in order to perform safety evaluations, diagnoses, retrofitting, etc. These properties are often difficult to estimate and may be measured using Destructive Testing (DT) methods, which are not always compatible with the structure under test, either because of the cultural value, the high cost or the excessive damage introduced. Therefore, this paper addresses a Minor Destructive Testing (MDT) technique with the purpose of measuring masonry shear properties. This represents a first contribution to a universally adopted and accepted MDT technique, which is not currently available. The present paper aims to study in detail the experimental results of four shear Flat Jack (FJ) tests from literature, by means of linear and non-linear analyses performed using micro and macro Finite Element models. These analyses are meant to study the ability of the shear FJ test for evaluating the shear modulus and the diagonal tensile strength of unreinforced brick masonry. The numerical results highlight the potential for the shear FJ test to become a suitable MDT method for evaluating the shear modulus and strength of brick masonry and evidence some aspects where further investigation is advisable.