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Old 4th April 2016, 12:17   #16
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

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Originally Posted by Mortis View Post
Very worrisome. A lot of the flyovers in Mumbai start wobbling a bit when there is heavy traffic on it. I hope strict action is taken against the contractor.
Actually that is a good thing. All flyovers need to wobble to dissipate energy, and also there are margins with rollers to enable expansion and contraction with temperature. A rigid structure with no expansion margins will collapse.
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Old 4th April 2016, 15:00   #17
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

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Originally Posted by alpha1 View Post
Whaat?!
Which flyover have you observed wobbling?



I was in Bangalore a few months back and on the way from Airport to Vivanta (Tumkur road), I saw a flyover section (under construction) which had one or two segments of naked steel structure (though not as pillars) between concrete beams.
I had uttered almost a similar sentence.
The Vile Parle flyover for one during morning peak hour traffic. Not noticeable while moving but when in a jam its quite obvious. Several others also over Mumbai. I dont think it could be some sort of resonance could it ?
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Old 4th April 2016, 15:32   #18
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

All vehicular flyovers and bridges are fitted with elastomeric bearings at the deck and column joint. These bearings act as shock absorbers to the sudden impact loading from heavy vehicles and they undergo real test in times of earthquake. They are designed to wobble/viberate in limits and these limits depend upon various factors.

An under construction flyover or bridge has high chances of failure than an already functioning one.
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Old 4th April 2016, 16:57   #19
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

Couple of interesting pics of Kolkata flyover (Vivekananda Flyover):

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~o~

News link:

http://www.thehindu.com/news/cities/...cle8423586.ece

~o~

Quote:
Originally Posted by alpha1

Whaat?!
Which flyover have you observed wobbling?
Even one can feel the wobbling effect on Bangalore's ORR twin flyovers (near Ecospace) during peak hour.
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Old 4th April 2016, 17:39   #20
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

I was about to ask this earlier, and those pics just reaffirm my concern. How did these people manage to get regulatory permissions to build a flyover with such thin (sometimes nonexistent) lateral clearances?

Given the demonstration of quality construction last week, I'd be horrified living in the vicinity, let alone under it.

Last edited by Chetan_Rao : 4th April 2016 at 17:41.
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Old 5th April 2016, 19:03   #21
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

Ok I guess it is a bit reassuring to know that some amount of vibration and wobbling is a normal event to be expected.
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Old 5th April 2016, 19:28   #22
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

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Originally Posted by sanjaykk View Post
However, what surprised me is that steel columns are being used as pillars for this flyover. I have never seen something like this in a flyover construction. Any civil engineers comments on this?
To save on space for foundation, especially on narrow stretches, this methodology was in use in Kolkata since several years. I had seen the fabricated steel columns in 2007 in several parts of Kolkata.
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Old 5th April 2016, 19:56   #23
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

Here in BLR, the upcoming Vidhan Soudha to Hebbal flyover is planned to be totally steel-fabricated off-site and simply assembled on site.

When it will happen is a different thing altogether...
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Old 5th April 2016, 20:28   #24
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Default Re: Flyover collapses in Kolkata (31st March 2016)!

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Originally Posted by sanjaykk View Post
However, what surprised me is that steel columns are being used as pillars for this flyover. I have never seen something like this in a flyover construction. Any civil engineers comments on this?
These are called steel girders as columns are always in vertical position. Steel girders are being used since many decades and are used where the constructor cannot block the space below it for many days. Concrete requires 28 days for curing (to become rock solid) and during this time the space below it will be blocked for traffic. Also, steel girders require less time to build, they are brought to the site and welded, bolted or riveted together (as per design) to form a deck where vehicles will ply.

This is the most basic reason among many other reasons.
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