Masonry material properties were based on those typical of wellbuilt ashlar construction and using a weak calcareous sandstone laid with a lime based mortar. The strength and stiffness of the modelled blocks have been based on average composite
values for the masonry treated as a whole. The contact and frictional behaviour of the mortar is modelled explicitly at the joints. Hence, it is not necessary to individually include the stiffness and strength of the joints or the stiffness and
strength of the stone blocks. Table 1 lists the material parameters used.
Table 1. Masonry Material Parameters.
Description
Parameter
Value
Sandstone/lime masonry
Density
2200 kg/m3
Young's modulus
3.5 kN/mm2
Strength
5 N/mm2
Mortar joints
Coefficient of friction (µ)
0.6
Cohesion
0.15 N/mm2
Adhesion
0
9. Loading
Hypothetical horizontal seismic loading based on a circular frequency of approximately 0.6 Hz and containing six shocks was derived and applied to all of the models as displacement functions at foundation level (Figure 4). Two magnitudes of
this simplified motion have been used with peak accelerations of 0.15g and 0.3g. Vertical accelerations were not considered due to the inherent inconsistencies in the distribution of mass that were required to simplify the problem to one of two
dimensions. Horizontal motion results in a greater proportion of the effective mass being distributed to the two shear walls than that corresponding to vertical motion. All load-bearing walls resist vertical motion. However, whilst concurrent
vertical motion has an influence on the overall behaviour of masonry shear walls, it is generally accepted that horizontal motion is more critical.
