The bridge deck of a highway in Hubei overturned. From a professional perspective, here is a guide: Are single-column pier bridges safe?

At about 3:36 pm on December 18, a rollover accident occurred at the Huahu Interchange D ramp (over-ramp bridge) of the Daguan Expressway in Wangbian Village, Ezhou City, Hubei Province. According to CCTV News, the accident has so far caused 4 deaths and 8 injuries.

The overturned D ramp of the Huahu Interchange on the expressway is the ramp of the Edong Yangtze River Highway Bridge, which was opened to traffic in September 2010. The construction unit is Hubei Road and Bridge Group Co., Ltd., and the design unit is the Hubei Transportation Planning and Design Institute/CCCC Highway Planning and Design Institute consortium. It has a single-column pier structure. The Edong Bridge Company, which is responsible for daily maintenance, believes that the cause of the accident was due to an overloaded truck, but whether it is true or not needs further investigation.

Some netizens also questioned that the cause of the bridge rollover was the single-column pier. So, is the single-column pier bridge safe? What kind of structure is it? In the future planning and construction of urban and highway bridges, is it still suitable to build a single-column pier viaduct? Let's see what Han Dazhang, chief engineer of the bridge department of China Design Group, has to say.

1

Advantages of single-column pier bridges:

Economical, beautiful, and less visual interference

"For this issue, the engineering community should adopt a scientific attitude and conduct a comprehensive analysis instead of treating it one-sidedly." Han Dazhang, chief engineer of bridges at China Railway Design Group, told reporters that single-column pier bridges have been used for a long time, and this structure is often used for urban interchanges and highway bridges. Its advantage is that it has only one pier, which has little interference with the driving line of the intersection, is transparent and beautiful, can improve the layout of the bridge's lower structure, and reduce the occupation of land. The engineering workload of single-column pier bridges is relatively small, especially when the cross-line is oblique, a smaller span can be used, which is more economical.

2

Disadvantages of single-column pier bridges:

The torsion resistance of the pier top is weak, but it can be improved through design optimization

Han Dazhang explained that in terms of the structural characteristics of a single-column pier bridge, its pier top does not have the ability to resist torsion unless the pier beam is consolidated. Therefore, under the traffic conditions of saturated road traffic and serious overload, special attention should be paid to the design of its lateral anti-overturning system. If pier beam consolidation is adopted, the pier body should have sufficient strength to resist the bending moment generated by the torsion of the beam on the pier body.

3

Is it still suitable to build single-column pier bridges in the future?

So, will we still use the single-column pier design in future viaduct construction? Han Dazhang said that at the end of 2018, the Ministry of Transport implemented the new "Highway Reinforced Concrete and Prestressed Concrete Bridge and Culvert Design Specifications", which clearly requires lateral anti-overturning design. "Since single-column piers have been widely used in urban bridges in the past, it is enough to show the advantages and rationality of this type of bridge. If it has some inherent deficiencies, we can ensure that they are inherently excellent in future designs."

For urban bridges, whether to use a single-column pier bridge is related to the surrounding construction conditions and should be determined based on the comprehensive considerations of land use, pipeline layout, traffic organization, urban landscape, etc. For highway bridges, their crossing methods and bridge width should also be considered reasonably. For existing single-column pier bridges, the traffic conditions should be investigated more. For bridges with low anti-overturning safety factors, they can be strengthened by weighting, setting up bearing tension devices, or even rearranging the bearings.

(Source: Xinhua News Agency, Upstream News, Jiaohuidian News, etc.)

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