Footbridge collapse in New Delhi 1

[msquared48]

Fine.

Then place a statement on the drawings/specs that if the construction sequencing/staging stipulated by the engineer of record ion these drawings/specs is either needed or desired to be deviated from, then the contractor must contact the engineer of record in writing for additional instructions, and receive those instructions prior to proceeding according to such instructions. To do otherwise relieves the engineer of record from any and all liability from any documented or undocumented damage, present or future, resulting from such action.

Are you confused now? I am.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[rowingengineer]

Hokie would be aware of the article in the engineers Australia this month about a similar bridge failure in Australia.

http://www.abc.net.au/news/stories/2010/08/24/2992277.htm?site=canberra&section=audio

It is very difficult in my mind to decide who gets the blame from an engineering stand point. In the review of the failure of the bridge above, 4 or so different engineering firms were involved in the project. The different bodies are: GHD superintendent, AECOM design of the highway, sellick consultant designer of temporary works, Aurecon design of temp foundations. Then there are the contractors all experienced in the construction of bridges, Reynders Constructions, IFS scaffolding, Abergeldie contactors, Roads ACT.

Smec is the consulting engineers reviewing the failure event and have indicated the failure is due: “Lateral bracing of the girders was absent which affected their stability and bending capacity when subject to both horizontal and vertical loads. Web stiffeners were not installed at critical locations near concentrated loads being transferred from the girders to the cross heads and the cross heads to the props. Props were not fixed to the foundations to prevent uplift in the case where there was deflection and rotation of the main girders. “

From this you can see that a lot had to go wrong for a collapse and every member of the team can be implicated.


An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[hokie66]

RE,
I hadn't read about that. That failure sounds like a failure of the temporary works, while the Delhi collapse appears to be a failure of the permanent works, albeit while still under construction.

 

[IFRs]

Is it possible that the design included the concrete slab to be a structural member, which of course it was not during construction?

 

[hokie66]

Yes, that is possible. If so, the builder missed the requirement to shore the structure. We may or may not find out the cause at some stage.

 

[kelowna]

To me it looks like the deck did not fail, nor the concreting sequence. I cannot see how concreting in any or other way might overstress the hanger to the deck connections, which, for me, is the failure point.

There was a new's bit saying that not all the hangers were connected, that would overstress the closest one, make it fail and creating a zipper effect.

Other options would be design flaw, connection overstress.

But one thing that suprises and bothers me is that in the photos I have seen, the socket forks, although some of them bent, appear to be intact, while pins cannot be seen anywhere. Those socket assemblies are designed to be stronger than the hanger, so if overstress failure occurs, it does so on the bar/hanger and not on the socket/pin assembly. What about putting wrong pin size or material? That would cause failure and an inexperienced contractor might miss it.

In any case, I do not think we will ever know for sure.

 

[BAretired]

Here is some breaking news about the collapse.

http://www.youtube.com/watch?v=iBddYYwuLyI

BA

 

[hokie66]

Different bridge collapse in Delhi, BA. This one on the Metro construction.

 

[hokie66]

The one you posted was in July 2009. Another one in October 2008. A dangerous place for bridge workers.

 

[BAretired]

Wow! I'll say.

BA

 

[STATICPH]

Hi,

Some of the cable connections are not destroyed, I think they contractor neglected to connect it, thus the steel frame was subjected to longer spans while casting the concrete, obviously will lead to failure………it not designed for that spans,

If you need a special method to construct a whatever structure, the engineer should advise the contractor on the method – or it’s sending a guy into a dog fight without telling him the dogs have rabies ?!?

 

[BAretired]

Nice metaphor, STATICPH, and welcome to the forum.

BA

 

[rscassar]

The stiffness of a reinforced concrete structure comes after the mass.

For the post which RE put up, the first two points sound like issues which should of been picked up by the engineer. When I'm onsite and see that lateral bracing has not been installed, I make note to the builder that bracing needs to be installed. Likewise the absense of web stiffeners should of been picked up by the engineer during the review of shop drawings.

 

[kelowna]

Update from NCE magazine.

http://www.nce.co.uk/news/structure...cted-in-delhi-bridge-collapse/8606393.article

You have to be a member to read it. I uploaded a print out of the news.

http://files.engineering.com/getfil...-40f7-9dd7-3e7a15fde26f&file=delhi_bridge.pdf