CYCLONE RESISTANT BUILDING BASICS AND TUTORIALS

BUILDINGS THAT ARE CYCLONE RESISTANT
How To Make Cyclone Resistant Building?


A cyclone is a storm accompanied by high speed whistling and howling winds. It brings torrential rains. A cyclone storm develops over tropical ocean and blows at speed as high as 200–240 km/hour.

It is usually accompanied by lightning, thunder and continuous downpour of rain. Cyclones extend from 150 km to 1200 km in lateral directions with forced winds spiralling around a central low pressure area.

The central region of light winds and low pressure, known as the ‘eye’ of cyclone has an average diameter of 20 to 30 km. This central eye is surrounded by a ring of very strong winds extending up to 40 to 50 km beyond centre.

This region is called ‘wall cloud’. In this region strongest winds and torrential rains occur. Beyond this region winds spiralling extend outwards to large distances, which goes on reducing with the distance from the centre of the cyclone.

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

1. Foundations should be deeper

2. R.C.C. framed structures are to be preferred over load bearing structures

3. Sloping roofs should be avoided.

4. Cantilever projections should be avoided.

5. Roof and parapet wall should be properly anchored to the columns and walls.

6. Height of the buildings should be restricted.

7. Suitable wind load should be considered in the building design.

8. Openings in the wall should be less.

9. Structure should not rest on loose soil.

IMPROVING EARTHQUAKE RESISTANCE OF SMALL BUILDINGS BASICS AND TUTORIALS

IMPROVING EARTHQUAKE RESISTANCE OF SMALL BUILDINGS BASIC INFORMATION
How To Improve The Earthquake Resistance of Small Buildings?


1. Site Selection: 
The building constructions should be avoided on
(a) Near unstable embankments
(b) On sloping ground with columns of different heights
(c) Flood affected areas
(d) On subsoil with marked discontinuity like rock in some portion and soil in some portion.

2. Building Planning: 
Symmetric plans are safer compared to unsymmetric. Hence go for square or rectangular plans rather than L, E, H, T shaped. Rectangular plans should not have length more than twice the width.

3. Foundations:
Width of foundation should not be less than 750 mm for single storey building and not less than 900 mm for storeyed buildings. Depth of foundation should not be less than 1.0 m for soft soil and 0.45 m for rocky ground.

Before foundation is laid remove all loose materials including water from the trench and compact the bottom. After foundation is laid back-fill the foundation properly and compact.

4. Masonry: 
In case of stone masonry:
• Place each stone flat on its broadest face.
• Place length of stones into the thickness of wall to ensure interlocking inside and outside faces of the wall.
• Fill the voids using small chips of the stones with minimum possible mortar.
• Break the stone to make it angular so that it has no rounded face.
• At every 600 to 750 mm distance use through stones.

In case of brick masonry:
• Use properly burnt bricks only.
• Place bricks with its groove mark facing up to ensure better bond with next course.

In case of concrete blocks:
• Place rough faces towards top and bottom to get good bond.
• Blocks should be strong.
• Brush the top and bottom faces before laying.

In general walls of more than 450 mm should be avoided. Length of wall should be restricted to 6 m. Cross walls make the masonry stronger. It is better to build partition walls along main walls interlinking the two.