Sihai network

Wuxi viaduct rollover causes: endless troubles after overload

Original title: expert analysis of Wuxi viaduct rollover accident: overload accident is not without solution

On the night of October 10, a bridge deck rollover accident occurred at k135 of 312 National Highway and Xigang road in Wuxi, Jiangsu Province.

According to the official microblog of Wuxi Municipal government, there are three cars under the bridge and five cars on the bridge deck, including three cars and two trucks.

As of press time, the accident caused 3 deaths and 2 injuries.

It is preliminarily determined that the accident was caused by overload

Peng Weibing, a professor at Zhejiang University of technology, and Dai Fei, an associate professor at West Virginia University, conducted a finite element analysis based on online public data, as well as photos and videos of the debris at the collapse site.

The team believes that the bridge accident can be preliminarily determined as the overturning damage of the beam bridge caused by severe overload and eccentric load.

Wuxi accident rescue headquarters also affirmed that the rollover of the overpass bridge was caused by overloading of transport vehicles.

Some on-site experts said that the accident was not caused by a single vehicle overload. Several overloaded trucks passed successively, resulting in the single pier bridge deck moving like a seesaw and eventually rollover.

Zhang Qiwei, Professor of Bridge Engineering Department of Tongji University, told China Science Daily that according to China's current highway and bridge design standards, the vehicle load grade of class I highway is highway-i, which is equivalent to a 55 ton multi axle vehicle plus several 20 ton vehicles in a fleet, and the vehicle spacing is greater than 10 meters.

According to the on-site news, the accident truck carried at least five 28 ton cylindrical steel coils. Combined with the self weight of the vehicle, the total weight of the vehicle and cargo was more than 150 tons, that is, it exceeded the maximum value allowed by the industry standard by about twice.

"Seriously overloaded vehicles greatly exceed the design calculation load, especially when the overweight vehicle runs in the lane on the side, it will produce a large overturning moment. If it exceeds the anti overturning capacity of the single column pier bridge, the bridge may overturn." Zhang Qiwei said.

If overload is not cured, there will be endless trouble

According to incomplete statistics, in the 12 years since 2000, at least 17 bridge collapses in China were alleged to be related to truck overload.

Since 2010, the Chunhui bridge accident in Shangyu, Zhejiang Province in 2011, the Qunli viaduct accident in the Third Ring Road in Harbin, Heilongjiang Province in 2012, and the bridge collapse caused by serious overloading of vehicles in Heyuan, Jiangxi and Guangdong high-speed ramp bridge in Guangdong Province in 2015 have occurred.

Among them, in the Qunli viaduct accident of the Third Ring Road on August 24, 2012, four overloaded trucks drove outside the bridge ramp on Honghu road at the same time, resulting in the side slip of the continuous steel-concrete composite beam of the bridge and the rollover of four trucks, resulting in 3 deaths and 5 injuries.

After the Gan Yue bridge accident in 2015, the Ministry of transport issued documents to provincial and municipal governments and issued a number of measures to further strengthen the treatment of illegal overload of roads and strengthen the construction and maintenance management of roads and bridges.

However, the Wuxi accident shows that the hidden danger of bridge collapse caused by serious overload has not been cured in China.

"If overload is not cured, there will be endless trouble!" A traffic expert who did not want to be named shouted, "we should call on relevant departments to study the inclusion of illegal overloading and transportation into the criminal law as soon as possible and start the legislative process."

Road administration alone is difficult to cure

According to Zhang Qiwei, the regulations on the administration of over limit transport vehicles on roads implemented by the Ministry of communications in 2016 clearly stipulates the types, loads and driving requirements of over limit vehicles, as well as the punishment for violations. When using over limit vehicles for transportation, you should submit an application for heavy cargo transportation to the highway management organization and drive according to the specified vehicle distance and speed in the allowed lane.

Peng Weibing and others believe that from the perspective of urban management, the real-time monitoring and management of overloaded and out of gauge vehicles should be further strengthened in the future.

In addition to strengthening the management of overloaded vehicles, in the bridge design, improving the design calculation to make the bridge more solid is also a way to reduce bridge safety accidents. Peng Weibing suggested that the anti overturning calculation method of curved beam bridge needs to be further improved; In addition, when the load is unpredictable, the final failure mode of the structure (bridge) should be controlled in the design to avoid overturning failure (brittle failure) before strength ductility failure.

"Although the state has regulations on heavy cargo transportation, illegal overloading still occurs frequently, and there are still underground refitting factories, which shows that it is difficult to cure the problem by relying on road administration alone, and the problem can be solved only through the coordination of road administration, transportation, vehicle management and other departments." Zhang Qiwei said frankly.

Solving the safety accidents caused by illegal overload involves the broad consensus and cooperation of the whole society. It not only requires the bridge design and construction units to improve the safety indicators of the bridge, the supervision and management departments to strengthen governance and improve management efficiency, but also requires the transportation owners to enhance their safety awareness, avoid fluke and no longer illegal overload transportation.

It is hoped that such accidents will be eliminated as soon as possible in China to provide road users with a safe driving environment.

Source: wechat account of China Science Daily