Science and Technology Daily reporter Li Yan
This afternoon, Guangdong Humen Bridge trembled abnormally. Many people passing by said that the entire bridge was shaking like waves, which caused heated discussion. Subsequently, the bridge management department closed the bridge. At 3:32 pm, the traffic management department implemented traffic control on Humen Bridge and reminded vehicles passing by to detour.
It is understood that experts in relevant fields have rushed to the scene. After integrating the opinions of teachers such as Liu Chengyin, Xiao Yiqing and Gu Lei at the Shenzhen Campus of Harbin Institute of Technology, experts analyzed that the on-site wind speed reached about 8m/s, causing the bridge's amplitude limiting vortex vibration. It is reported that at present, the Humen Bridge is under maintenance and construction, and a 1.2-meter-high retaining wall is added to the bridge deck, which destroys the cross-sectional streamline and causes vortex vibration. At present, the retaining wall is being removed.
Humen Bridge is a cross-sea bridge in Guangdong Province connecting Guangzhou Nansha District and Dongguan Humen Town. It is a main part of the Guangzhou-Shenzhen-Zhuhai Expressway Network. Because it connects the two sides of the Pearl River, connects important cities such as Shenzhen and Zhuhai , and is an important transportation hub in the coastal areas of Guangdong. The construction of the Humen Bridge started in 1992; it was completed and opened to traffic in 1997; and passed the completion acceptance in 1999.
Humen Bridge is a national key project. Many technologies have won innovation awards for
Humen Bridge, with nearly 3 billion yuan investment, is a national key project. It has a number of advanced domestic or international engineering technologies and processes. It is the first truly large-scale modern suspension bridge in my country. It is considered to mark the highest achievement in China's bridge construction in the 20th century.
"Although Humen Bridge is located in a typhoon-prone area, this factor has been fully considered at the beginning of the design, and the wind resistance coefficient is definitely very high. As we all know, the most feared thing about bridge safety is resonance, but these factors have been fully considered and avoided at the beginning of the design." Jia Yong, an architectural designer at Shenzhen Yibu Design Company, has been engaged in bridge design for a long time. He told Science and Technology Daily reporters, "The Humen Bridge has only been 20 years since now, and most of the bridges in my country will be designed according to a century-old plan, so it is unlikely to be a design defect."
During the construction of Humen Bridge, my country's large-span modern suspension bridge technology can be said to be a blank stage, and there are no ready-made construction technical standards and design specifications. Such as the design of suspension bridges, wind resistance and stability, the manufacturing of large castings, the production and welding of ultra-wide stiffened steel box girders, large-scale construction special equipment, construction erection, construction control, etc., all require independent design and solution by the Chinese team. Although China had early experience in designing and construction of large-span continuous rigid frame bridges, facing the larger span of Humen Bridge, some key technologies brought about by the lightweight structure in the design need to be solved.
From the later situation, Chinese engineers completed the design and construction work well. The industry generally believes that the Humen Bridge has a special status in the history of my country's bridges, not only because of its important geographical location, but also because of its large scale, novel structure, and great influence from the external environment. Both design and construction are the first attempts in China. Because of this, the Humen Bridge project not only won the Zhan Tianyou Civil Engineering Award, but also won the Guangdong Science and Technology Progress Award and the National Science and Technology Progress Award.
real-time monitoring system for bridges is indispensable, but maintaining the security of good and bad bridges, including earthquake resistance and wind resistance are key elements in design and construction. Generally speaking, it is normal for a bridge to shake slightly, but if the amplitude is very large, you should pay attention. In order to understand the safety elements of bridges in real time, modern bridges generally have health monitoring and evaluation systems. This is a system that combines software and hardware. It collects and analyzes data on various aspects of bridge cracks, waterways, and traffic flow. At the same time, it conducts real-time monitoring and early warning of the bridge's ambient temperature, concrete stress and strain, vibration, and displacement.
Industry insiders told Science and Technology Daily that Humen Bridge also has such a monitoring system. Through real-time monitoring of the continuous displacement of the bridge, we can understand the actual stress state and working conditions of the bridge structure under various actions, and evaluate the mechanical characteristics of the structure and its working performance under the action of designed loads.At the same time, by analyzing the monitoring results, the vibration parameters of the structure are obtained, and the wind and seismic design of the structure is verified, so as to achieve real-time safety monitoring of large-span bridges.
It is worth mentioning that the industry insider said that the monitoring system of a building is not easy to maintain. Generally, software and hardware need to be updated in about ten years. Some projects may not be replaced and updated in time. However, he also emphasized that bridge monitoring is the most important of all buildings. An important hub monitoring system like the Humen Bridge should maintain good operation.
U.S. Tacoma Strait Bridge was destroyed by the breeze
For the abnormal shaking of the Humen Bridge, many people thought it was caused by the excessive wind speed of the main bridge at that time. But some local people also said that although the wind was quite strong at that time, it was "not particularly exaggerated."
Speaking of which, there has been no wind in history, but the bridge collapsed. The most famous one is that the Tacoma Strait Bridge collapsed in the breeze.
Tacoma Strait Bridge is a suspension bridge located in Tacoma, Washington, USA. There was a swing during construction, and after the bridge was completed and opened to traffic, it swayed even more violently. It is said that on some days, the vibration amplitude of the bridge's body reached 1.5 meters, making the driver unable to see the car driving in front of it. Local people call it the dancing Gotty. In 1940, four months after opening to traffic, the bridge suddenly collapsed. According to records, the wind speed was not high at that time. Such wind speed should not be a threat to the bridge, but the bridge was still dramatically destroyed by the breeze.
This collapse was considered to be due to the intricate aerodynamic and structural analysis, which had a profound impact on the subsequent bridge design and construction. Later, all bridges, whether as a whole or in part, must pass rigorous mathematical analysis and wind tunnel testing. Aerodynamics and resonance experiments have become compulsory courses in architectural engineering.
