Moscow Market Roof Crash Kills 47 For those who aren't already following this story, the Basmanny market in the Bauman district on the east side of Moscow collapsed at approximately 5:45 am on Thursday, February 23. (Video from NTV)The victims of the collapse are reportedly municipal and market workers. Mayor Yuri Luzhkov said all the dead were workers from outside Moscow. Most Moscow markets are staffed by migrants from the former Soviet republics of the Caucasus region and Central Asia. Russian media reported some market workers lived in the basement of the building; many migrants encounter trouble getting police permission to live in Moscow apartments. That process to get registration to live in Moscow is a topic for another day, however. Coincidently, the architect for this building is Nodar Kancheli, who also designed the Transvaal Park swimming pool complex, whose roof collapsed in February 2004. From an earlier AP update:
The architect who designed the covered market said in a radio interview that its flat roof had not been designed to bear a heavy load of snow. "It seems there was a lot of snow, and nobody removed it," Nodar Kancheli was quoted by Itar-Tass news agency as telling a Moscow radio station. "Nobody was allowed to get on to the roof to clear it off." Kancheli was charged in April 2005 with negligence over the design of the Transvaal Park swimming pool complex, whose roof collapsed in February 2004 under the weight of snow, killing 28 people and injuring 200. He has denied responsibility.However, Moscow Mayor Yuri Luzhkov has reported the roof was designed to clear itself of snow.
"The roof was designed to take a large amount of snow cover, and there was a special gutter pipe that was always left open so the melted snow could run down, so there was no special need to have the roof cleared of snow," the mayor told reporters.Credit goes to rescue workers who appeared to be quickly on the scene. Various reports cite between 100 to 150 survivors may be trapped under the approximately 2,000 square meter roof. According to ITAR-TASS, Moscow prosecutor Anatoly Zuyev will be investigating at least three possible contributing causes to the collapse:
Luzhkov said that the Bauman Market, also known as the Basmany market, was among buildings designed by Kancheli's firm that had been checked for safety after the Transvaal disaster.
Among versions, he called “violation of the rules of operation, improper implementation by the market management of safety engineering rules and wrong designing of the building”.
Now I will put on my engineer hat for some comments.
There is just no way that a properly designed building in Moscow should collapse under an estimated seasonal snowfall of 20 inches of snow. Mr. Luzhkov is at least partially correct; a properly designed building should drain itself of water from rain and melting snow, as the biggest danger is an accumulation of heavy wet snow, from freezing and thawing cycles. And keeping the gutter pipe clear of ice and frozen debris is also critical. Further, if Moscow building codes are not designed to accomodate snow live loads from 20 inches of snow, then the rooftops should be cleared before now. But it is rather hard to believe that only 20 inches would impinged upon the structural design factors of safety to an extent that failure would result. Not seeing the layout of the building and locations of kiosks and such, it is difficult to determine what contribution they made to the buildings collapse. This sounds like a roof collapse, and based upon photographs, the whole thing came down like a pancake on top of the underlying kiosks (and building occupants). This could be the result of one column failing and a resulting "zipper" effect as load is transfered from the failed columns to the remaining columns, resulting in their failure - and so on down the line.
However, given how flat the collapse of the structure appears in photos, it seems more like some sort of failed connection of the roof to the columns (update: seeing more photos of the overall scene makes me think it is a column failure and zipper effect). With the Transvaal Park swimming pool roof collapse, I had suspected something similar, with corrosion of some key connections. Corrosion due to chlorine and moisture in the air is a common problem with swimming pools, that has resulted in failures here in the US and elsewhere. It is difficult to see what might have caused corrosion, if any, in this collapse. Further, whatever evaluation was done of this architects prior buildings was clearly not sufficient. Obviously, these buildings will have to be revisited, with a clear eye towards common design elements. Reevaluation of the structural plans, as well as comparing these plans to the actual construction of the building (surprise, but buildings aren't always built exactly according to the plans) will also be required.
Update: More details on the buildings construction are found on NTV's website. Based on my poor translation of this, it appears to be a cable-suspended, steel reinforced concrete roof. The roof fell straight down and is partially suspended by internal walls, trapping people in the open spaces underneath. Apparently the architect has designed two other similar buildings with suspended cable roofs.
Update II: Mikhail Moskvin-Tarkhanov, Chairman of the Planning and Development Commission of the Moscow city Duma, has an opinion column, citing the poor construction practices (строительстве халтура or construction hack-work) of the 1970s Brezhnev era, as a contributing factor in the Basmanny market roof failure. He calls for reinspection of all similar large, open-spaced roof designs from the 1970s, in sports facilities and elsewhere.