PAULO B. LOURENCO*, JAN G. ROTS** and ROB VAN DER PLUIJM***
*University of Minho **Delft University of Technology
***Eindhoven University of Technology
The lack of experimental data for the complete characterisation of the inelastic behaviour of masonry is a key issue in numerical modelling of masonry structures. A solution to obtain the material properties of masonry at the macro-level is to derive them on the basis of the geometrical and material properties of the underlying constituents, namely unit and mortar (micro-level). An interface model for the joints and cracks in the units, which includes a tension cut-off and the Coulomb friction law with variable dilatancy, is used to show that the macro-behaviour of masonry under tension parallel to the bed joints can be effectively predicted. The obtained stress/displacement response measures the fracture energy of masonry (that is the area under the curve, including the descending branch) and can be used as a material property for macro-models, where a relation is established between average masonry stresses and average masonry strains. The basis for the reliable use of techniques, in which micro-models are used to predict some of the macro-properties of masonry, is the existence of deformation controlled test results at micro- and macro-level. Only a thorough comparison between predicted and observed results can provide the necessary level of confidence for future use of such techniques. This calls for better co-operation between experimentalists and analysts as well as increasing financial support.