Chiefly, DE simulations were carried out to show how the strength and ductility of the walls varied with reinforcement arrangement. However, for both the plain and reinforced wall No.3 (considered most probable), mortar with and without
cohesion has also been considered. This limited investigation into the influence of mortar properties was carried out to allow comparisons to be made with earlier, simpler work. Where walls have exhibited a high degree of seismic resistivity, an
additional ground motion with peak accelerations of 0.3g has been applied. The results have been illustrated by arrays of contour diagrams in which, the friction behaviour in the joints, magnitude of ground motion and the position of reinforcement
have been varied.
a. Unstrengthened Simulations.
(1) The aim of the current investigation is to develop a pattern of reinforcement that works equally well for plain walls as well as those with openings. In the model, the idealised opening has been created using a smeared1 cell
approach where approximately 36% of the wall is removed. The predicted ductility of the walls is highly sensitive to the properties of the joints and the duration of the event (Brookes, Mehrkar-Asl, 1998). In addition, the inherited damage
history from preceding shocks increases the seismic vulnerability of the wall.
(2) In Figure 7, compressive stresses and deformed geometry half way through the seismic event and after ground motion has ceased (5.2s and 12.5s respectively) are shown. The shaded contours range between 2.2 N/mm2 (dark) and -0.2
N/mm2 (330psi and –30psi respectively). The plain wall is also loaded with a 0.3g ground motion. After the 0.15g events, the plain wall remains relatively undamaged with cracking in both storeys. The cracks in the second storey
result in significant dilation across the wall whereas the cracks in the first storey are less dilated and are associated with locked in stresses. Doubling the acceleration results in massive damage. With much less masonry capable of resisting
shear, the wall with openings is severely damaged after three shocks and collapses before the end of the event.
