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