You could be responsible for seismic safety

[kanthraj]

That which shook some Indian cities, foreign media as well as ours just a few weeks back cannot be forgotten. The impact was so widely felt that the Nepal-North India earthquake has led to a round of discussions across expert panels. ‘How you can be responsible for your seismic safety?’ Here are the highlights-

To make a structure safe, you should take care of the following parameters-

•Dwelling should be a framed structure. It acts as an integrated member for the floor, slab, beam, columns. The structure may tilt but it wouldn’t collapse with such an arrangement
•It should contain resisting elements such as shear walls. There cannot be an earthquake resistant structure without the use of shear walls especially in a high risk zones such as Delhi. Its use ensures security because it is a reinforced concrete wall which is integrated to the bottom beam as well as the roof beam. In case of an earthquake, the wall wouldn’t collapse
•All the elements such as walls and the roof should be tied together so as to act as an integrated unit
•The foundation should be sound enough, commensurate to soil condition. Without analyzing the bearing capacity of the soil, structures shouldn’t be planned because tremors start underground

Example of a framed structure as follows. The building splits into two independent blocks and tilts but doesn’t collapse.

Due to improper reinforcement, instead of acting as a monolithic structure, the column has given way at the bottom which could be fatal during an earthquake. Therefore, apart from selection of material, utilisation and placement of the material requires expert attention.

Experts took up the following consumer queries-

What is retrofitting? What should we ensure?

In the case of a community living, the entire community needs to be taken into confidence. It is not enough to go by what a builder tells you. Even structural engineers need to develop their skills, be more equipped, understand codes, and digest recommendations. They need to analyse whether the structure is safe. While you are waiting for manuals to come out, you should also approach consulting engineers who would study your building structures. If you have bought from a reputed developer and ask for an assessment. If you still feel that there should be an additional comfort level, you could approach experts at academic institutions who would guide you about whether you have been looking for things you should have been looking for.
Are there agencies that look into earthquake resistant structures today ?

None of our structural engineering courses have paid attention to studying such structures commensurate to the magnitude of the problem. There are some pointers that need to be followed. A) The property seller needs to maintain data- what kind of soil, B) The kind of foundation, since a structural engineer would not be able to dig the foundation to study it. If this data is in place, it would be easier to study the resistance on the scale of 1-10. C) The steel to concrete ratio needs to be maintained. Ductility has to be ensured in case of an earthquake resistant structure. In an earthquake prone area, the steel ration has to be increased in order to make the beam column ductile.

At what stage of development can we ask for a structural safety certificate?

Even before the builder starts the construction, you should approach him to tell him about your needs. Tally a structural engineer’s checklist with your builder’s data bank. After the progress of construction, ensuring safety is not possible and whenever possible, very costly.

How would I know if the certificate is authentic?

If the building authorities are giving you a certificate, there would be a check because there is some amount of testing happening. Second, get an independent valuation done. Third, in the absence of a checklist, we would ensure that a checklist is provided to buyers.
Apart from this, a builder should be made to give an affidavit to ascertain credibility. In foreign countries, the builder is made accountable for a collapsed building. We need such responsible builder communities in India as well.
If built area has been neglected, perhaps it is time for you to point out the gaps in what is done and what ought to have been done. Response mechanism has worked in many cases where diagnostic mechanisms have been ignored. As a consumer, ask for more!