Estimation of settlement-induced damage in masonry buildings from displacement measurements

In current engineering practice, building damage due to nearby ground excavation activities is typically quantified by processing displacement measurements. Building displacements at discrete points are used to determine deflection measures (such as angular distortion) which are then employed to estimate building strains using elastic beam models; damage is subsequently categorised according to the limiting tensile strain criteria. The reliability of this procedure relies on the extent to which the equivalent beam models employed in the analysis provide a realistic representation of the building behaviour. However, few published investigations are available on this issue. The current paper provides an appraisal of displacement-based building damage estimation techniques by employing digital image correlation displacement data collected from a recent experimental campaign on the settlement response of three half-scale masonry buildings. The results demonstrate that the treatment of buildings with equivalent beam models does not capture building deformation kinematics, potentially leading to inaccurate estimations of damage severity and location. An alternative strain interpretation procedure, inspired by an equivalent frame idealisation of a building façade with openings, is proposed. This procedure, which uses a limited number of displacement measurements, offers a robust interpretation of strains. Its effectiveness in estimating damage is assessed through experimental data. It is demonstrated that the current limiting tensile strain criteria need to be modified to provide a reliable estimation of crack widths when using the equivalent frame idealisation.