Since earthquakes are becoming commonplace, it is imperative that all building projects be earthquake proof basis the seismic zone they are in. Here are some pointers to ensure your structure can withstand a moderate earthquake.
1) The building should be able to sustain as much side-ways motion as possible, in order to minimize damage to the structure and give the occupants time to get out safely.
The most dangerous building construction, from an earthquake point of view, is non-reinforced brick or concrete block. Generally, this type of construction has walls that are made of bricks stacked on top of each other and held together with mortar. The roof is laid across the top. The weight of the roof is carried straight down through the wall to the foundation. When this type of construction is subject to a lateral force from an earthquake the walls tip over or crumble and the roof falls in like a house of cards.
2) Use light weight civil engineering materials as far as possible, especially for walls and roofs.
3) Cement mortar used should be in the ratio of 1:6 parts of sand.
4) The use of seismic bands: a seismic band consists of a concrete flat runner at the plinth level of the building and the lintel level of all doors and windows.
5) Use vertical reinforcement in brick walls. this reinforcement should start from the foundation and run through all the seismic bands.
FOR LARGER BUILDINGS:
1) Use of dampers,rollers, tire mats or other foundation cushion plates to allow for sliding.
Tuned mass dampers are large masses built on top of buildings that can sway at the top of the building in opposition to the building sway. These devices can reduce the sway of a building up to 30 to 40 percent.
2) Expansion joints for larger buildings especially where 2 different types of foundations are being used.
3) isolated footings instead of fixed base foundations
As the buildings get bigger and taller other techniques are employed such as “base isolation.” During the past 30 years, engineers have constructed skyscrapers that float on systems of ball bearings, springs and padded cylinders. Acting like shock absorbers in a car, these systems allow the building to be decoupled from the shaking of the ground.
Remember, we cannot avoid earthquakes but we should prepare for them.