Mixed structural systems with concrete or steel columns and structural masonry walls behave very unfavorable during earthquake.
The columns in combination with the slabs or beams form frames, which have a smaller horizontal stiffness than the Masonry Walls. Therefore to large extent earthquake actions is carried by the masonry walls.
When masonry walls fail due to the seismic actions or deflections, they can no longer carry the gravity loads, which leads to a total collapse of the building. Mixed systems of columns and Structural Masonry Walls must be absolutely avoided.
This mixed system also result in lack of flexibility.
