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Figure 2. Stone masonry shear wall details (all dimensions in mm)
7. Discrete Element Model
Several plane stress DE models of a single side wall were developed incorporating the masonry blocks and slabs. The vertical loads and masses attributed to the slabs were modified to reflect mass and load transfer from the rest of the building.
The wall is constructed from ashlar blocks, bedded on narrow and relatively weak lime-mortar. Without full scale testing of part of the wall, uncertainties exist for most material parameters and indeed the modelling. Previously both macro block
and brittle material masonry models were used to help characterise wall behaviour (Brookes, Mehrkar-Asl, 1998). The focus of the work was the sensitivity of structural behaviour to equivalent friction of the mortar joints rather than the relative
performance of different strengthening arrangements. In the current investigation, masonry material parameters have been fixed and based on those most representative of the form of construction. Similarly, macro block models have been used
throughout so that the focus of the investigation is on the effectiveness of strengthening.
Figure 3. General arrangement of idealised building
Although it is feasible to include all of the blocks in the macro block representation, previous work on masonry arches had shown that there was little advantage in terms of accuracy and computational efficiency. Hence, each block in reality
may include several squared stones. The floor slabs and foundation were defined as separate continuums with similar perimeter frictional properties to the blocks. It has been assumed that the floors and foundation are constructed such that their
global behaviour is linearly elastic e.g. reinforced concrete slabs. All models were developed within a solid modelling environment using DISPLAY3 (EMRC, 1999), translated using in-house software and imported from within the ELFEN pre-processor.
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