Low Cost Housing in Earthquake ..!

Low Cost Housing in Earthquake Seismic Zone

by Mr. Pradeep Kumar Barik, CTS, Bhubaneswar

An Article from Our Building & Construction / October 2015

Unreinforced masonry (URM ) buildings are the most

preferred shelter for the people in the world belonging to lower economic bracket. Particularly in India, about two-third of the total Population lives in masonry structures because of ease of construction, availability of material and limited cost.

Performance of such structures under gravity loading is quite satisfactory. However, their Performance is very poor during extreme loading events like earthquake, wind or blast load.

URM buildings suffered severe damages leading to a collapse during medium to large earthquakes leading to significant losses of life and property in the past earthquakes.

During the last 20 years, a number of earthquakes Struck India. Past earthquakes in India (i.e Bihar, 1988; Uttarkashi, 1991; Jabalpur, 1997; Chamoli, 1999; Bhuj, 2001; Andaman, 2002; Sumatra, 2004; Kashmir, 2005; Sikkim, 2006; Sumatra, 2007;Durgapur, 2008; Sikkim, 2011) showed the poor seismic Performance of URM buildings. In this regard, it is the need ofthe hour to find ways and means to strengthen URM buildings,which are the habitats of the majority of population of the world.

Many researches were carried out to strengthen/retrofit

these structures using composite materials. However, this

is not only costly but also requires technical manpower

and sophisticated equipments for their implementation. In

this context, the present study proposes few alternative,

low cost and sustainable strengthening approaches for

URM buildings in improving their earthquake resistance.

Strengthening Techniques..!

URM buildings need to be strengthened to minimize

the casualties and economic loss during earthquakes.

Research on simple strengthening techniques without

requiring any technical rigour and appreciable

enhancement in cost, for URM structures are extremely

terse. Extent of failure in URM buildings in the occurrence

of earthquake may ränge from horizontal shear failure,

comer/junction failure and failure of out-of-plane walls to

total collapse of the structure in a brittle manner.

Moreover, presence of horizontal and vertical mortar layers

becomes the cause of weakness for initiating failure

in URM buildings. The tension and shear carrying capacity

of mortars is too low and becomes the reason of failure. In

this context, strength and stiffness of the structure needs

to be worked on.

Further, the strengthening should be aimed at Converting the brittle behavior of URM structure to ductile to the extent possible. In view of the above facts, the use of poly propylene (PP) band (commonly used as packaging material), horizontal L-shaped reinforcing bars and chicken wire mesh may be used as strengthening materials for URM structures.

These techniques applied individually or in combinations

maybe effective in improving the overall enhancement in

tension and shear carrying capacity. Further, it may also be

effective in improving the Joint behaviour. By using the

above strengthening techniques, the integrity of the

structure will improve.

Conclusion..!

In order to frame any guidelines, one needs to experiment

(varying the dimension, aspect ratios, thickness, type of

mortars and different quality of material) using the above

proposed strengthening techniques. The above proposed

techniques will not require any technical manpower or

sophisticated equipments for implementation.

Further, the low cost and environment friendly (sustainable

approach) will make the technique populär for the non engineered structures. Another important aspect may also be investigated regarding the use of URM buildings using fly ash bricks instead of clay burnt bricks.As the less mass of fly ash brick made masonry structures will enchain less earthquake forces.

By adopting the above proposed techniques after conducting number of experiments, the casualties and economic loss will be minimized in the developing countries which are frequently visited by low to moderate earthquakes.

Source: New Horizons

 Other Main articles in October 2015 B&C Issue 

Lakshmi Ceramics Now in Chennai

Bamboo Mat Moulded Skin

For Doors

Sweden’s ‘Twisting Skyscraper’ wins CTBUH Award

K-Lite’s New Lighting Poles

Low Cost Housing in Earthquake

L&T 60 landmark buildings

Home Plan 

B&C Publications

No. 22/2, Welcome Colony, 

Thirumangalam,

Anna Nagar West, 

Chennai, 

Tamil Nadu - 600 101.

INDIA. 

E mail: bandcpublications@gmail.com

Web Site: www.bandcpublications.com

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