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Karachi Bridge Collapse

Karachi Bridge Collapse

Karachi Bridge Collapse

(OP)
The following is the news about Karachi bridge collapse. According to the news it says, no bridge in the world has ever been constructed without support on the turning (structural curvature), suggesting that this bridge lacked support over a long curved section.  According to the media, that original design called for a longer curve on the bridge at its turning point which required 174 feet of space. But there were 100 shops in the vicinity,  So National Highway Authority redesigned the bridge with a curve fitting in 144 feet. This made traffic either slow down and turn or turn at higher speeds causing more centrifugal forces on the bridge.

What is your opinion from the structural point of view?

KAYTWO

Karachi bridge collapse seen as tragic engineering failure
Released on 04/09/2007

Collapse of the Karachi Port Trust’s newly built elevated roadway is a disaster for the city, now carrying out a major scheme of infrastructure development with the support of the Pakistan Government.

This part of the huge ‘Tameer-e-Karachi’ project was ordered on the direct instructions of President Musharraf, who came to Karachi in August to inaugurate what is known locally as the KPT flyover project.

Its principal purpose is to give the port trust direct access to the national highway system as well as to relieve traffic congestion in the city.

But after only four weeks in commission, the structure collapsed on September 1, killing as many as ten people and trapping many more under heavy slabs of concrete.

Eye witness reports say that the 70-metre curved section of the bridge fell about 15 metres onto the road below.

Reports in the Pakistan press quote unnamed engineers as saying that no bridge in the world has ever been constructed without support on the turning (structural curvature), suggesting that this bridge lacked support over a long curved section.

Sources told Pakistan’s International News that in mid-February, a foreign team arrived to inspect the bridge after serious defects had been discovered. It is said they recommended that it should be reconstructed.

The flyover/bridge was built under the overall supervision of Pakistan’s National Highway Authority. Design and construction supervision was in the hands of NESPAK (National Engineering Services Pakistan), listed as Pakistan’s premier consultancy organisation.

This is a private limited company set up by the Government of Pakistan in the 1970s with the aim of creating a pool of talented engineers who would replace foreign consultants.

The company claims to have largely achieved these objectives, and now enjoys the reputation of being one of the top engineering consultancy firms in Asia and Africa.

The KTP project was built by Pakistan’s Frontier Works Organisation, a contracting group which, since its formation in the 1960s, has gained a high reputation for economy and efficiency in the field of civil works and infrastructure.

The tragedy of this engineering failure seems likely to be the outcome of an innovative approach to difficult issues posed by the structure’s location and the volume of traffic that has to be distributed across a complex roads network.

The cost is high, as many as 10 deaths, many injuries and financial losses which could amount to many millions in dollar terms, quite apart from compensation for the bereaved and injured.

The Pakistan Government is understood to have set an inquiry in motion and meanwhile to have suspended certain officials from the National Highway Authority and others involved in building the structure.

RE: Karachi Bridge Collapse

the beam has not failed, seems like shear failure adjacent to supports, or could it be the centrifugal forces on the curve which made the girder to slip on one side.

once the bridge was open to public it again was closed just after one week of use, and then rehabilitation works were done, using carbon fibre reinforcements. after two month it was reopned for use and just after 17 days of use it came down.

i would surely like experts here to comment on it.

RE: Karachi Bridge Collapse

It appears that the pier also turned over. Either, the cenrifugal force caused it to turn over or the foundation settled.

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