Bridges are a significant invention in human history. From ancient times when people used felled trees and stacked stones to cross waterways and ravines, to the use of arch bridges and even cable-stayed bridges, the evolution has been remarkable. The recent opening of the Hong Kong-Zhuhai-Macao Bridge marks a crucial milestone in the history of bridges. In modern bridge construction, in addition to using reinforced concrete structures, metal materials, particularly aluminum alloys, have become the mainstream choice due to their various advantages.
In 1933, the world’s first aluminum alloy bridge deck was used on a bridge spanning a river in Pittsburgh in the United States. More than ten years later, in 1949, Canada completed an all-aluminum arch bridge spanning the Saguenay River in Quebec, with a single span reaching 88.4 meters. This bridge was the world’s first all-aluminum alloy structure. The bridge had piers approximately 15 meters high and two lanes for vehicular traffic. It used 2014-T6 aluminum alloy and had a total weight of 163 tons. Compared to the originally planned steel bridge, it reduced weight by about 56%.
Since then, the trend of aluminum alloy structural bridges has been unstoppable. Between 1949 and 1985, the United Kingdom constructed approximately 35 aluminum alloy structural bridges, while Germany built around 20 such bridges between 1950 and 1970. The construction of numerous bridges provided valuable experience for future aluminum alloy bridge builders.
Compared to steel, aluminum alloy materials have a lower density, making them much lighter, with only 34% of the weight of steel for the same volume. Yet, they have strength characteristics similar to steel. Additionally, aluminum alloys exhibit excellent elasticity and corrosion resistance while having lower structural maintenance costs. As a result, they have found extensive application in modern bridge construction.
China has made significant strides in bridge construction as well. The Zhaozhou Bridge, standing for over 1500 years, is one of the pinnacle achievements of ancient Chinese bridge engineering. In the modern era, with the assistance of the former Soviet Union, China also built several steel bridges, including the Yangtze River bridges in Nanjing and Wuhan, as well as the Pearl River Bridge in Guangzhou. However, the application of aluminum alloy bridges in China appears to be limited. The first aluminum alloy structural bridge in China was the pedestrian bridge on Qingchun Road in Hangzhou, built in 2007. This bridge was designed and installed by German bridge engineers, and all materials were imported from Germany. In the same year, the pedestrian bridge in Xujiahui, Shanghai, was entirely developed and manufactured domestically using aluminum alloy structures. It primarily used 6061-T6 aluminum alloy and, despite its 15-ton self-weight, could support a load of 50 tons.
In the future, aluminum alloy bridges have vast development prospects in China for several reasons:
1 China’s high-speed rail construction is booming, especially in the complex terrains of western regions with numerous valleys and rivers. Aluminum alloy bridges, due to their ease of transportation and lightweight properties, are expected to have a significant potential market.
2 Steel materials are prone to rust and have poor performance in low temperatures. Corrosion of steel significantly affects bridge stability, resulting in higher maintenance costs and safety hazards. In contrast, aluminum alloy materials have strong corrosion resistance and perform well in low temperatures, making them suitable for various climate conditions and ensuring long-term durability. While aluminum alloy bridges may have higher initial construction costs, their low maintenance expenses can help reduce the cost gap over time.
3 Research on aluminum bridge panels, both domestically and internationally, is well-developed, and these materials are widely used. Advances in material research provide technical assurance for developing new alloys that meet different performance requirements. Chinese aluminum manufacturers, including industry giants like Liaoning Zhongwang, have gradually shifted their focus to industrial aluminum profiles, laying the foundation for aluminum alloy bridge construction.
4 Rapid urban subway construction in major Chinese cities imposes stringent requirements for structures from above ground. Due to their significant weight advantages, it is foreseeable that more aluminum alloy pedestrian and highway bridges will be designed and used in the future.
Edited by May Jiang from MAT Aluminum
Post time: May-15-2024
