Building collapses in its entirety

Building collapses in its entirety (Shanghai,China – July 2009)

 

(Shanghai, China)  —  The development, known as “Lotus Riverside,” had a total of 629 units, 489 of which had been sold. The assets of the project’s developer, Shanghai Meidu Property Development Co., were frozen and the city officials said the developer’s ability to repay homebuyers was secure, according to a statement on the municipal government’s website.  

The disaster revealed some uncomfortable facts about lax construction practices in China, where buildings are put up in a hurry by largely unskilled migrant workers, and developers may be tempted to take shortcuts.

According to Shanghai Daily, initial investigations attribute the accident to the excavations for the construction of a garage under the collapsed building. Large quantities of earth were removed and dumped in a landfill next to a nearby creek; the weight of the earth caused the river bank to collapse, which, in turn, allowed water to seep into the ground, creating a muddy foundation for the building that toppled.

The South China Morning Post noted that the pilings used in the Lotus Riverside development, made of prestressed, precast concrete piles, are outlawed in Hong Kong because they aren’t strong enough to support the kind of ultra-high buildings that are common in Hong Kong. But in mainland China, they are often used because buildings there are typically much shorter.

Quality problems have long plagued construction in China, though they seem to be more apparent in rural areas and smaller cities, not in major metropolises such as Shanghai and Beijing. When school buildings were flattened by the massive Sichuan earthquake, a number of parents faulted shoddy construction for creating “tofu buildings” that fell while other nearby structures were able to withstand the impact of the quake. More recently, state media reported that several new dams along the Yellow River are in danger of collapse, a situation attributed to shoddy construction practices, embezzlement and unqualified workers.

The series of events that lead to the disaster:

1) An underground garage was being dug on the south side, to a depth of 4.6 meters
(2) The excavated dirt was being piled up on the north side, to a height of 10 meters
(3) The building experienced uneven lateral pressure from south and north
(4) This resulted in a lateral pressure of 3,000 tonnes, which was greater than what the pilings could tolerate.
Thus the building toppled over in the southerly direction.

First, the apartment building was constructed.

 

Then the plan called for an underground garage to be dug out.
The excavated soil was piled up on the other side of the building.

 

Heavy rains resulted in water seeping into the ground.
 The building began to shift and the concrete pilings were snappeddue to the uneven lateral pressures.