An experimental investigation of the static and dynamic behaviour of masonry assemblages using small scale models
The last 10 years has seen a renewed interest in the behaviour of unreinforced masonry panels under earthquake loading. Research on full scale structures requires massive, expensive test equipment, is time consuming and costly in manpower. Full scale testing therefore, has been limited to specific, very narrow investigations. Modelling at a reduced scale offers immense savings with wider possible fields of study. The first stage of the author's work was aimed therefore at developing prototype materials for 1: 4 scale models, and establishing their fundamental mechanical properties. A complete description of the material properties should provide all the parameters for numerical and analytical predictions and for static and dynamic testing of prototype replicas at the small scale. The parameters investigated in the static testing phase included compressive, tensile and shear strength, Young's modulus and Poisson's ratio, shear modulus and brick-mortar interface bond among others. The second stage involved the development of a shaking table and the investigation of six low-aspect, confined, infill panels subjected to sinusoidal cyclic loading. The study investigated their dynamic behaviour and energy dissipation capacity with progressive damage. Parametric studies were conducted with respect to the brick, mortar and masonry strength. The damage was photographically documented and the cracking propagation is detailed from the initial stages up to collapse. Classic full scale cracking patterns and failure modes were observed which gave the author considerable confidence in the model results. Shear-ductile failures were recorded for panels confined by low axial compressive forces which seems in part to contradict some current opinion, but reference is also given to similar findings published recently in scientific journals. The final component of the work was concerned with a numerical assessment using a commercially available finite element program incorporating a non-linear concrete constitutive material model. This numerical model was fine-tuned by using the previously obtained experimental data to simulate cracking patterns of small masonry specimens under static load.