China News Network, Hangzhou, June 23 (Reporter Zhang Bin correspondent Xu Liting Lu Yunyu) From 19:00 on June 18, the Xihoumen Bridge in Zhoushan, Zhejiang Province, caused about 70 minutes of vortex-induced resonance due to strong winds. In the early hours of the same day, the bridge adopted measures for orderly passage of limited models. On June 23, Tian Hao, director of the Bridge and Tunnel Engineering Research Institute of the Zhejiang Provincial Institute of Transportation Research, said in an interview that this vortex-induced resonance will not affect the safety of the bridge structure.
"Vortex-induced resonance will not affect the safety of bridge structures"
After the vortex-induced resonance occurred at the Xihoumen Bridge in Zhoushan, the management unit promptly adopted two-way sealing measures. After the expert's argument, through the analysis of the monitoring data of the bridge structure, based on the monitoring vibration data and the feedback of the artificial real bridge, the bridge has recovered to the level before the vortex-induced resonance, and there is no abnormality. From 24:00 on June 18th, Xihoumen Bridge has adopted orderly traffic measures for limited vehicles.
"By comparing key data such as the main beam stress, main beam deformation, and main cable force before and after the occurrence of previous vortex-induced vibrations of the Xihoumen Bridge, the acceleration and displacement amplitudes of this vortex-induced resonance are all within the allowable range of the specification, not It will cause structural strength damage, and the possibility of fatigue damage of components is also small, so it will not affect the safety of the bridge structure." Tian Hao said.
As an expert who has long been involved in the study of vortex-induced resonance phenomena, Tian Hao has carried out popular science on the phenomenon of vortex-induced resonance phenomena. He said that the so-called vortex-induced resonance phenomenon, that is, when the airflow flows through the structure, is affected by the shape of the member, wind speed and other conditions, will produce regular vortices, if this vortex is close to the natural frequency of the structure, it will produce vortices Resonance phenomenon.
"It's like a knife inserted in the water, the water will ripple, the bridge exists in the air, and the wind will vibrate, but the vibration of the wind is invisible to the naked eye." Tian Hao said, in simple terms, the vortex The most intuitive feeling of the excited resonance phenomenon is that the wind is shaking the bridge, and the bridge surface is oscillating like a wave. At this time, the driving may not be so comfortable. This is also the short-term time after the vortex-induced resonance of the Xihoumen Bridge. One of the reasons for closure.
"Vortex-induced resonance phenomena have been considered in bridge design"
It is understood that the Xihoumen Bridge is a large-span suspension bridge designed and constructed by China itself. When the bridge was completed in December 2009, it was the world's largest span steel box girder suspension bridge. A monitoring system is installed on the bridge, which can make real-time judgment on the safety of the bridge. Since the Xihoumen Bridge was opened to traffic, 20 to 30 vortex-induced resonance phenomena have been monitored each year, each lasting for 10 to 300 minutes, and the acceleration and displacement amplitudes are within the allowable range of the specification.
In addition to the Xihoumen Bridge, Zhejiang Province provides special bridge health monitoring systems for important bridges with special structures. The bridge condition is monitored 24 hours a day, and as long as the data is abnormal, relevant measures will be taken.
"Not long ago, the vortex-induced resonance phenomenon also occurred on the suspension deck of the Humen Bridge connecting the east and west sides of the Pearl River Estuary." Tian Hao said that the vortex-induced resonance phenomenon is something that must be faced by bridge construction. The design, construction and Management will fully consider this. ,
Zhejiang Transportation Department also reminded that if driving encounters the phenomenon of vortex-induced resonance, don't panic, keep a distance from the vehicle in front and pass at normal speed. (Finish)