Avoid bracing of frames with masonry infills
The frame structure is relatively flexible and somewhat ductile, while unreinforced masonry is very stiff and fragile and may explode under the effect of only small deformations.
At the beginning of an earthquake the masonry carries most of the earthquake actions but as the shaking intensifies the masonry fails due to shear or sliding. The appearance of diagonal cracks is characteristics of a seismic failure.There are two cases:
- With stronger columns the masonry is completely destroyed and falls out.
- With weaker columns the masonry can damage and shear the columns, which often lead to collapse.
