Brace masonry buildings with reinforced concrete structural walls!
Masonry is a good construction material in terms of thermal insulation, storage and vertical loads carrying capacity. For seismic actions however, masonry structures are not well suited. On one hand they are relatively stiff, so they usually have a high natural frequency- within the plateau area of the design response spectrum- and therefore experience large earthquake actions. On the other hand unreinforced masonry walls are rather brittle and generally exhibit relatively little energy dissipation.
Best solution is to brace unreinforced masonry buildings with reinforced concrete structural walls. Therefore it is possible to limit the horizontal deformations of the masonry and preserves its gravity load carrying capacity.
The reinforced concrete walls must be designed to be sufficiently stiff,the horizontal wall length and the vertical reinforcement ratio being key parameters. They must be able to carry seismic actions and to transmit them to foundations while remaining elastic i.e. without notable yielding of the reinforcement.
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