an orthotropic continuum model for the analysis of masonry structures

4 1995 TNO-95-NM-R07120.50.10.20.30.4σyσxσyσ xyσxFig. 5 - Yield surface for hollow units masonry proposed by Ganz (1989) with iso-shear stress linesContour spacing: 0.1 f mxFinally, it should be realised that a masonry macro-model always includes some degree of approximation.The basic features of a two-material composite cannot be reproduced but only smeared outin the continuum. The Þeld of applications of these models are indeed large structures where thestate of stress and strain across a macro-length can be assumed uniform. It is noted that, due to thedifÞculties of carrying out experiments in large structures, the examples used in the present reportfor the assessment of the model performance (extracted from available literature) are, in general,ÒsmallÓ for a macro-modelling strategy.The model proposed in the present report seems however capable of reproducing the globalbehaviour of the analysed structures. Satisfactory predictions of collapse loads are also found providedthat the structures do not show a highly localized failure mode. In such cases the interactionbetween units and mortar can be of capital importance and a micro-model, in which both masonrycomponents are modelled separately, should be used instead.