CYCLONE RESISTANT BUILDINGS

A cyclone is a storm accompanied by high speed howling and whistling winds. It can bring torrential rains. A cyclone storm made over Tropical Ocean and blows at speed as high as 200-240 km/hour. Usually it is accompanied by thunder, lightning and continuous downpour of rain. Cyclones extend in the range 150 km to 1200 km in lateral directions having forced winds spiralling around a central low pressure area.

The central region of low pressure and light winds which is known as the 'eye' of cyclone has an average diameter of 20 to 30 km. By a ring of very strong winds extending up to 40 to 50 km beyond centre this central eye is surrounded. This region is known 'wall cloud'. In this particular region torrential rains and strongest winds take place. Winds spiralling extend outwards to large distances beyond this region, which will reduce along with the distance from the centre of the cyclone.

In designing buildings the following care should be taken in cyclone prone areas:

1.   R.C.C. framed structures are to be preferred over load bearing structures
2.   Foundations should be deeper
3.   Sloping roofs should be avoided.
4.   Roof and parapet wall should be anchored to the columns and walls properly.
5.   Cantilever projections should be ignored.
6.   Appropriate wind load should be considered in the building design.
7.   Height of the buildings should be restricted.
8.   Structure ought to be not rest on loose soil.
9.   Openings in the wall should be less.