Avoid mixed systems with columns and masonry walls!
The columns in combination with the slabs or beams form frames, which have smaller horizontal stiffness than the masonry walls. The earthquake actions are therefore carried to a large extent by the masonry walls. In addition to the inertia forces from their own influence zone, the walls must resist those from the parts of the building with the columns. This result in a seismic resistance considerably less than that of pure masonry construction. When masonry walls fail due to the seismic actions or deflections, they can no longer carry the gravity loads, which usually leads to a total collapse of the building.
Such mixed systems is unfavorable because of their lack of flexibility with regard to increasingly frequent building modifications required by changes in their use.
