This way you don't manage the disaster
DISASTER MANAGEMENT BY INSHA FEROZ KHAN
Recently the state’s disaster management cell in collaboration with other bodies conducted mock drills in different towns of the valley to create awareness among people and ask them how to act during earthquakes. They tell you to be at certain places of the building when an earthquake hits. But what if the building floor fails under your feet or the roof falls down over your head or the walls fall sideways? Since, our valley falls in the seismic zone V, it is vulnerable to most severe earthquakes (may be of magnitude 8 or more) and what is worse is that most of our buildings can’t withstand such earthquakes. So, before making people aware of how to be safe within a building, the disaster management should first make people aware of how their buildings can be safe during an earthquake.
Earthquakes are the strongest, the quickest, and the most unexpected of all the natural calamities. The primary concern in earthquakes is of course human casualties i.e. deaths and injuries. Civilizations throughout the history have been gripped with the fear of earthquakes because of their devastating effects and we too have witnessed the severe devastation caused by the earthquake that hit the valley on 8th of October 2005. Besides, the recent earthquakes in Haiti and Chile brought devastation to the two cities, is also known to us. Hence, constructing safe buildings is the prerequisite for saving life and property from the damage and not the mock drills.
Being a student of civil engineering, I am making an attempt to put forward the engineering approach for such earthquake challenges. But, however, it is also important to keep in mind that there is no such thing as an earthquake-proof structure, although seismic performance of structures can be greatly enhanced through proper initial design or subsequent modifications. The construction of new structures should strictly be done on the consultation of a civil engineer because it is crucial that adequate attention is given to earthquake considerations at the correct stages during construction. The already existing structures can be strengthened to withstand the earthquake tremors by a technique called RETROFITTING. Retrofitting is such a kind of technique, which is applied to a building as an extra protection with additional support. Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. Some of the retrofitting techniques are:
(1) Use of earthquake bolts. These can be tightened and loosened to support the house without having to otherwise demolish the house due to instability.
(2) Excavations can be done around the building and the building is separated from the foundations. Steel or reinforced concrete beams replace the connections to the foundations, while under these, the isolating pads, replace the material removed. While this method tends to restrict transmission of the ground motion to the building, it also keeps the building positioned properly over the foundation.
(3) One simple retrofit is to surround the column with a jacket of steel plates formed and welded into a single cylinder. The space between the jacket and the column is then filled with concrete.
Similarly, there are lots of other retrofitting techniques that can be utilized for strengthening our structures. However, the strengthening may be limited to connections between existing building elements or it may involve adding primary resisting elements such as walls or frames, particularly in the lower stories.
Also, it should be noted that, wood is one of the best materials for earthquake resistant constructions since it is of low mass and is relatively less brittle than masonry. It is easy to work with and a good shock absorber. However, it is only resistant if the structure is properly connected to its foundation. The existing stock of important lifeline buildings is vulnerable to earthquake failure and need to be retrofitted to raise their level of performance in Earthquakes. Hence, the benefits of retrofitting include the reduction in the loss of lives and damage of the essential facilities, and also the functional continuity of the lifeline structures. For an existing structure of good condition, the cost of retrofitting tends to be smaller than the replacement cost. Thus, the retrofitting of structures is an essential component of long term disaster mitigation and should be taken into account for strengthening of the structures now than to repair them after the loss of lives and property later. So, we should act now towards safety using engineering principles than to wait for disasters using mock drill principles!
[Insha Feroz Khan is a student of Civil Engineering in National Institute of Technology, Srinagar].
Lastupdate on : Fri, 26 Mar 2010 21:30:00 Makkah time
Lastupdate on : Fri, 26 Mar 2010 18:30:00 GMT
Lastupdate on : Sat, 27 Mar 2010 00:00:00 IST
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