Delhi Airport Terminal Roof Collapse 1

[AlexEss]

https://www.bbc.com/news/articles/c725ny6p960o

 

[jayrod12]

Not sure why this didn't gain any traction, It's a pretty serious looking collapse for a building that is less than 30 years old. Lack of lateral system for the giant canopy?

 

[3DDave]

Lack of any follow-up information will slow discussion.

 

[JohnRBaker]

I've flown in and out of the Delhi airport several times. The last time was in November 2006.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[human909]

Lack of lateral system for the giant canopy?

Those diagonal steel struts would provide excellent lateral. They also provide inferior vertical capacity unless suitably sized and tied appropriately for the axial tension that results.

 

[jayrod12]

Those diagonal steel struts would provide excellent lateral. They also provide inferior vertical capacity unless suitably sized and tied appropriately for the axial tension that results.

Fair point, I tried to find a google streetview of it before collapse before commenting, but google maps didn't show anything. I don't really know much besides the pictures in that link.

 

[jayrod12]

Found one. Something still feels spindly about the look in this picture.

edited to keep the thread cleaner, wrong terminal.

 

[bones206]

The above looks like a different area, not the collapsed structure...

[image

https://res.cloudinary.com/engineer...0-350f-11ef-a044-9d4367d5b599.jpg_tdpd0j.webp

]

https://res.cloudinary.com/engineer...0-350f-11ef-a044-9d4367d5b599.jpg_tdpd0j.webp

[/image]

 

[bones206]

This is what it looked like prior to collapse. Ponding due to drain failure?

https://www.youtube.com/shorts/BdMmJVhwKBc

 

[3DDave]

Google doesn't have streetview of the airport, but when the little man is selected there are spots that show up. This looks to match the collapsed structure.

 

[phamENG]

Wow. The angles on those slanted columns are way too extreme.

 

[human909]

Wow. The angles on those slanted columns are way too extreme.

Agreed. A strut design like that performs best when loads are similar on each strut. If they are dissimilar then you get rotation at the strut base AND/OR additional bending load in the deck above.

In the case of heavy rain you could readily get excessive deflection which would then cause deep ponder and it all becomes a reinforcing loop of increasing deflection and ponding until collapse.

 

[SWComposites]

Perhaps someone forgot to check buckling. See it far too often when people run an FEA analysis thinking the basic static analysis covers all failure modes.

 

[FacEngrPE]

Granted there may have been a member design problem, but -
It could just as easily been designing to a roof load specified, instead of figuring out how much water would be on the roof when it spills over the side, and using that as the design roof load.
From the video (bones206) it appears that the roof was full to the spill over point.

 

[LittleInch]

It looks like there is a rise on the end leading to a shallow valley, hence the two bendy drain pipes probably just got overloaded, though given India has monsoons you would have thought they would get that bit right. Maybe one got blocked and then once a dip started it just accelerated until failure.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Sym P. le]

New Delhi (Indira Gandhi International) Terminal 1 - The arc of the roof terminates along the front driveway support column line. This means half of the entire roof drains along that column line. I don't see that there is extreme depth to the ponding area so the support design is most suspect. I question whether this water shedding concept is suitable for monsoon type rains.

Edit: As I look closer, there appears to be ponding at the south end of the roof extension (top of image), which is the section that failed. The image is dated 2016. Google Maps appears to show new roofing for the southern 2/3 of the roof extension.

From bones' video, two downpours caught the videographers attention, both between the southern two columns and both at the junction of the diagonal with the eave. This all points to human909's theory of an unbalanced load being the likely culprit.

 

[Tomfh]

These box gutter systems, where water cannot overflow in case of a blockage, have caused many roofs to collapse. It’s a terrible way to build roofs, as the water load can greatly exceed design limits once the roof blocks. For whatever reason architects despise external gutters and downpipe. They want their "clean" appearance.



Speculation about buckling struts might be a premature, as many other factors are at play; The roof was recently modified, with additional bays added. Initially, there were 5 columns with 5 pairs of struts.

https://www.google.com.au/maps/@28....ro-0-fo100!7i6144!8i3072?coh=205409&entry=ttu

Now, there are extra bays, and some of the original columns have additional struts added.

Also, the interior support struts have broken loose intact. These struts may have detached cleanly from the truss above, indicating connection failures are occurring. This could be the case at the outside too, as opposed to buckling struts.

 

[Sym P. le]

I see it more as a hinging mechanism where the struts meet on the column. Any movement in the roof structure could cause the connection failures. I note also that the airport has undergone significant upgrades since the 2016 photo.

 

[Tomfh]

It’s just had a major upgrade. It was modified over the past few years, and reopened a few months ago.