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[Dr. N. Subramanian]

Hi All,
One important aspect of tall building is the maintenance, which is often forgotten. We see a number of buildings in Chennai and other Indian cities, especially constructed by Housing or Slum Clearance Boards, which look ugly because of poor maintenance. Of course they are all 4 storied only. If the high rise buildings are maintained like that, the look of the city itself will be bad. When I visited Singapore, I found that all the tall buildings were looking fresh. I was told that the Singapore Govt. will take over the maintenance, if the owners are not doing so, every 5 years or so, and will ask the owners to reimburse the same with fine. Of course, now a number of Aluminium facades are available, which require minimum maintenance.

Instrumenting high raise buildings for the determination of wind/ EQ/ other loads is done in a few cases. I learnt that about 400 buildings in Singapore are instrumented- see the news item at the end. Has any building in India instrumented like that?

Best wishes,
Subramanian

A Milestone in the Structural Health Monitoring (SHM) of High-Rise Buildings- 400 Buildings in Singapore Are Monitored

Singapore and its city landscape of tall buildings have reached a significant milestone: 400 high-rise buildings are now instrumented and monitored with Structural Monitoring with Fiber Optic (SOFO) sensors. Structural Health Monitoring is becoming recognized in the domain of civil engineering as a proper means to increase the safety and optimize operation and maintenance of high-rise buildings. As part of the quality assurance of new tall building construction in Singapore, a large-scale lifetime high-rise building monitoring program has been implemented since 2001.

Since then, a substantial number of high-rise buildings have been instrumented and monitored withSOFO fiber optic sensors. The monitoring aims of this unique program have been to increase safety, verify performance, quality control, increase knowledge, optimize maintenance costs and evaluate the condition of buildings after earthquakes, impacts and severe atmospheric conditions.

SOFO long-gage fiber optic strain sensors have been embedded in fresh concrete of ground-level columns of each building, so that the monitoring has started from the beginning of the project. Measurements have been performed during construction, upon completion of each new storey and roof, and after the construction, including long-term creep and shrinkage.

地基的不均匀沉降再保险corded and post-tremor analysis after earthquakes in neighboring countries has also been performed continuously. The deployed monitoring system has been performing very well and all sensors work properly more than 10 years after their embedment in concrete. Unusual behaviors were detected at early stage of the construction, demonstrating high sensitivity of sensors and suitability of the monitoring requirements through every stage of the building lifespan including construction and in the long-term.

The use of fiber optic sensors on such a large scale for monitoring of high-rise buildings is a first in Singapore and in the world, and it sets directions that will help designers to better understand the behavior of tall buildings during their life cycle, from construction to service conditions.

[B.V.Harsoda]

Respected Dr. NS Sir,
As you have been said that "now a number of Aluminium facades are available, which require minimum maintenance."
I believe that if aluminium facades used, proper ground earthing of aluminium plates shall be done toprevent lightning strikes.
Am I right or wrong ?

Regards,
Er. B. V. Harsoda

[B.V.Harsoda]

[Dr. N. Subramanian]

Dear Er Harsoda,

I am not sure about it. Please check with the manufacturers

Warm regards,
Subramanian

[B.V.Harsoda]

Respected Dr. NS Sir,

Thank you very much for reply.

Recently I have seen Following information at web

http://www.lightning.org/?page=home

http://www.lightning.org/faq/

As below:-
If I live in an aluminum-sided house, what impact does that have on lightning safety? I have a pole-mounted anemometer on my roof. Is this a likely target for lightning?

事实上你有铝墙板没有妊娠和分娩综合管理t on the likelihood of a strike to your residence. Obviously metal is a better conductor than most building materials, which are insulators, but the attractive effect is minimal for isolated metal bodies. Metal siding generally isn't grounded, like your electrical system, your water piping system, or the structural steel framing on some buildings. Grounded systems, if they are elevated above the roof line, are very good strike points for lightning, but siding, flashings, copings or guttering of metal don't have the same ground path, and aren't much more attractive than non-metallic items.

Things that come to a point like roof peaks, ridges, chimney corners, etc. easily release ions, whether they are metallic or not, which makes them valid strike points for lightning. This brings us to your anemometer mast. It meets all the requirements for an improved lightning strike point.
It is taller than the surrounding area, made of metal, comes to a relative point, and is grounded. Now it depends on how it is "grounded" to determine if it acts as it's own lightning rod or not. If it is only grounded back inside to the equipment or electrical system, you may be bringing lightning back into the house. If it is grounded using only a small electrical ground conductor, it may work once and then the wire could vaporize. If the outside ground conductor comes in close proximity with any other building grounded system, even through a wall, that isn't interconnected with the ground conductor, the lightning could side-flash into the other system. Even if this device functions as a "good" lightning strike point and conductor, it only protects about 2 to 1, so if it is 10 ft. above the roof line it protects an area of around 20 ft. radius from it's base. Any part of the house outside this area is subject to a direct strike, according to the lightning protection Standards.



Warm regards,
B. V. Harsoda