The bridge also has a "golden bell cover", so you don't have to worry about being hit anymore!

Recently, the news that Nanjing Yangtze River Bridge was equipped with "anti-collision armor"

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Does a seemingly stable bridge also need anti-collision measures?

What is the principle of “anti-collision armor”?

The Nanjing Yangtze River Bridge was completed and opened to traffic in 1968. It is the first double-deck railway and highway bridge on the Yangtze River designed and built by China. It is of great significance in the history of bridges in China and the world. It is an important achievement of China's economic construction and an important milestone in China's bridge construction. It has great economic, political and strategic significance and is known as the "Bridge of Reputation".

Image source: Nanjing News

However, as the bridge was built at an early age, with the increasing number and tonnage of various types of ships sailing on the Yangtze River in recent years and the increasingly dense shipping routes, ship-bridge collisions are inevitable, and the risk of bridge piers being hit by ships is increasing.

For example, on May 12, 2013, a cargo ship "Xinchuan No. 8" registered in Weihai, Shandong, carrying 12,539 tons of limestone, suddenly turned at a large angle while preparing to pass the Nanjing Yangtze River Bridge downstream, and collided with the bridge pier between the sixth and seventh bridges, causing the hull to be damaged and water to enter, eventually sinking.

Data shows that every year, major accidents of bridges being severely damaged or even collapsed due to ship collisions occur, resulting in astonishing casualties, property losses, and environmental damage. Many ship collision accidents can cause losses of tens of thousands of yuan, while serious ones can cause casualties, losses of millions, tens of millions, or even billions of dollars. The large amount of indirect losses is even more difficult to calculate.

Arkansas River bridge and boat collision

Jiujiang Bridge ship collision accident

Ship collision accident on Taiyangbu Bridge

Jintang Bridge ship collision accident

Pictures of the scene of the serious ship collision

In order to avoid or reduce the losses caused by ship-bridge collisions, it is particularly necessary to add anti-collision facilities to the piers of the Nanjing Yangtze River Bridge.

At present, there are many types of bridge pier anti-collision facilities at home and abroad.

Its basic principle is based on

Designed for energy absorption and momentum buffering

Each anti-collision facility has its own characteristics and conditions of use.

Specifically

Most bridges at home and abroad use artificial islands

Group piles, rubber fenders

Anti-collision structures such as steel casings

Mitigating the damage caused by ship-bridge collisions

Anti-collision facilities

Rubber fender anti-collision devices are widely used in port and dock projects. They are easy to install, low in maintenance costs, and reusable. However, they absorb little collision energy and are difficult to withstand head-on collisions with large ships.

In view of the many drawbacks of traditional anti-collision facilities, it is urgent to design and develop new anti-collision systems using new materials.

In recent years, in view of the limitations of traditional materials, fiber-reinforced resin-based composites (FRP) have received great attention. In addition to excellent properties such as light weight, high strength, good designability and corrosion resistance, they also have good energy absorption.

Composite anti-collision facilities can effectively reduce the damage to bridges and ships caused by collisions, and have the significant advantage of bidirectional protection between ships and bridges . More and more cross-river and cross-sea bridges have chosen this advanced composite material as the anti-collision facilities of bridges.

Wuhan Yingwuzhou Yangtze River Bridge

Taking the circular cross-section composite material anti-collision system as an example, it is mainly composed of a composite material outer tube, an inner tube, a polyurethane elastic bonding material between the inner and outer tubes, and a lightweight friction granular material filled inside the inner tube.

The inner and outer tubes of the anti-collision system are made of glass fiber reinforced vinyl resin composite materials, which have good mechanical properties and can withstand the huge impact force from ship collisions. They are also resistant to seawater corrosion and maintenance-free.

The polyurethane elastic material filled between the inner and outer cylinders of the composite material has high shear resistance and interface bonding performance, and strong buffering capacity; the lightweight friction particle material filled in the inner cylinder can effectively improve the rigidity of the inner cylinder, and can limit the deformation of the inner and outer cylinders to ensure that they do not deform too much and cause rupture, and consume a large amount of impact energy through friction and extrusion, which can effectively alleviate the impact caused by the collision of the ship. The circular cross-section ring appearance design allows the ship to slide away as soon as possible and take away as much residual kinetic energy as possible.

Therefore, cross-river and cross-sea bridges equipped with such composite anti-collision facilities will have a "golden bell cover".

Image source: CCTV News Client, China Government Network

Nanjing Release, Sina Weibo, Baidu, etc.

References:

[1] Zhao Fan, Fang Hai, Liang Zhiwen, Zhu Lu, Han Juan, Wang Sheng. Experimental and simulation study on ship collision energy absorption of fiber reinforced rubber composite soft body system[J]. Journal of Xi'an University of Architecture and Technology (Natural Science Edition), 2022, 54(02): 184-190. DOI: 10.15986/j.1006-7930.2022.02.004.

[2] Fang Hai, Wang Jian, Zhu Lu, Liu Weiqing. Research on anti-ship collision device of the middle tower pier of Wuhan Yingwuzhou Yangtze River Bridge[J]. Bridge Construction, 2020, 50(01): 20-25.

[3] Fang Hai, Deng Xiangyang, Deng Chenggang, Wang Lixin, Liu Weiqing, Wu Zhimin. Research on the technology of anti-collision facilities using new composite materials for bridge piers[J]. China and Foreign Highway, 2014, 34(04): 148-153. DOI: 10.14048/j.issn.1671-2579.2014.04.037.

[4] Liu Weiqing, Fang Hai, Zhu Lu, Han Juan, Wu Zhimin. Theoretical analysis of ship-bridge collision force and composite material anti-collision system[J]. Journal of Southeast University (Natural Science Edition), 2013, 43(05): 1080-1086.

END

Author: Du Tianyu

Review expert: Zhou Sanfeng, School of Civil Engineering, Nanjing Tech University

Editor: Guru