MATTHEW GILBERT* TOM MOLYNEAUX** and BRIAN HOBBS*** * University of Sheffield **UniveTsity of Liverpool***University of Teesside

A three-dimensional non-linear finite element modelling approach suitable for describing the response of unreinforced masonry structures subjected to short duration dynamic loadings is described. As the performance of many types of modern unreinforced masonry structures is largely governed by the mechanical behaviour of the joints, a three dimensional interface formulation suitable for modelling joint fracture has been developed. Crack propagation at joints is modelled according to a cohesive crack type law. The presence of dilatancy at the unit/mortar interface is also modelled. The performance of laterally loaded, stretcher bonded, concrete blockwork walls in particular is studied. It has been found that reasonable agreement between experimental test results and numerical predictions may often be obtained, and that dilatancy may be a particularly important factor when short duration loads are involved.