Dwarka Expressway collapse 1

[Tomfh]

https://www.indiatvnews.com/news/in...pressway-flyover-collapse-injured-toll-693990

CCTV footage:

https://www.youtube.com/watch?v=41o96-c0UP0

 

[bones206]

There's a sudden upward deflection on the left span prior to collapse. Right at the 18 second mark of the video.

 

[cooperDBM]

Possible torsion failure in left span? Is the bridge curved?

 

[bones206]

Similar collapse last year?

https://www.youtube.com/watch?v=BSlgXhl0wYo

 

[Ingenuity]

Is the bridge curved?

Based upon this screengrab it appears straight at the collapse location:

Screengrab from this video @ 3:38: Link

 

[human909]

There's a sudden upward deflection on the left span prior to collapse. Right at the 18 second mark of the video.

Good spot.

My guess is a compression failure in the bottom flange induced from PT loads possibly along with uplift from the bridge builder itself. As the concrete crushes at the bottom the span momentarily lifts as friction the bottom flange shortens until it collapse back on itself and shears the tendons.

That's just a guess. I'm a concrete and bridge rookie.

 

[bones206]

Sounds like a good guess to me. In the video I linked to of the other similar collapse, a commenter said the same thing, with poor concrete quality being the main culprit.

 

[FacEngrPE]

If the concrete is so far requirements so much that a compression failure occurs in a precast component, then perhaps the entire already built structure is suspect.
[ul]
[li]Is cured concrete tested in India as is often specified in the US? [/li]
[li]Or perhaps not enough cure time to develop full strength before setting and post tensioning the segments?[/li][/ul]

Fred

 

[bones206]

If you have two similar collapses, in very similar viaduct structures, in the same city, within 7 months, I'd say meets the definition of suspect. No idea as to construction practices in India, but I'm sure there are many local engineers on this forum that can speak to that. At least there were no serious injuries or fatalities in either of these incidents, thank god for that.

 

[LittleInch]

Also are those middle sections of the beam supposed to be located over the main pillar?

Looks to me like they are off the main support and hence part of the load of all the new sections are being supported by the previous section.

But yes you can see the concrete breaking off, the bridge rears up momentarily before collapsing.

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