Construction Issue
plate to the east ; and to the west , we have got the North America plate and the Eurasian plate . And what is happening is that the Philippine plate and the Pacific plate are heading towards the west ; they are going underneath the other two plates and that is what is causing all the problems .
With all we know about earthquakes and their causes , can we forecast when they may occur ?
While it may seem that we know much about tectonics , faulting , and the processes that cause earthquakes , it is not safe to assume that we have the ability to forecast earthquakes . While a few examples of successful predictions have indeed occurred , many have failed , and some powerful earthquakes have hit , with no warning , in settings similar to those where successful predictions had previously been made .
So how does earthquake inflict damage of lives and property ? Well , if you are at field , and earthquake happens , it ’ s more likely you feel like as if you getting a weakness stroke . Damage and loss of life sustained during an earthquake result from falling structures and flying glass and objects . Examples are numerous but the results have been same . Innocent people caught under debris and succumbed to load and suffocation .
Can Earthquake be averted ? No certainly not . Can the fatalities and losses be reduced ? Yes . It ’ s been said that , ‘ Prevention is better than cure ’ and same thing goes with our construction practices too . If the building is yet to be constructed , we have an option to reinforce the building as per codes and building is constructed under proper supervision . But if the building are old and URM ( unreinforced masonry building ) there are three broad approaches to managing the risk posed by URMs :
buckling due to excessive bending combined with axial load . The buckling of columns is significant when the columns are slender and the spacing of the stirrup in the column is large . Severe crack occurs near the rigid joints of frame due to shearing action which lead to complete collapse . Most of the damage occurred at the beam column junction . Widespread damage was also observed at the interface of stone or brick masonry infill and r . c . frame . In most of the cases diagonal cracks appeared in the stone or brick infill .
The failures are due to mainly lack of good design of beams / columns frame action and foundation . Poor quality of construction . Inadequate detailing or laying of reinforcement in various components particularly at joints and in columns / beams for ductility . Inadequate diaphragm action of roofs / floors . Inadequate treatment of infill masonry walls . Inadequate strength to resist torsional forces due to eccentricity . The concreting between the beam and the column junction is done afterward , where honey combing in concrete cannot be avoided fully . Buildings have been raised on cantilever beams leading to failure . The buildings have been constructed on reclaimed land without proper foundation . Buildings have subsided and tilted due to liquefaction in the foundation soil . Building resting on soft soil or reclaimed land without proper foundation is likely to get damage due to uneven settlement due to earthquake shaking .
Damage to URM Buildings :
1 . Do nothing and live with the risk on the basis that damaging earthquakes occur infrequently ; 2 . Demolish , RCs & URMs , which would have an impact on the heritage and character of country ’ s towns and cities ;
3 . Install some level of strengthening .
Damage to R . C . Frame Buildings :
The damage is mostly due to failure of infill , or failure of columns or beams . Spalling of concrete in columns . The column damaged by cracking or