Fortified structures
An earthquake is marked by two types of simultaneous motions: a lateral, push and pull motion and an undulating or pitching motion which moves surface structures up and down. The damage to a building depends on how much and how long the ground motion lasts, the nature of the soil and the nature of the structure itself.
Since the earthquake force is a function of mass, the building should be as light as possible, particularly its roof and upper storey. How the structure responds depends in turn on its properties as well as on its damping characteristics or its capacity to absorb the forces acting upon it. Concrete has better damping properties than steel. Brick buildings suffer during earthquakes because the roofs tend to separate from the supports due to the shaking; the walls tend to tear apart moving diagonally.
These effects can be minimised by tying all the various parts of the building together. A horizontal band can be used at the roof, lintel and plinth levels to bind the building together. Bands can be provided in the walls to tie the structure together and to impart horizontal bending strength. By providing these minimum features, 90-95 per cent of the building is safe.