China News Service, Guangzhou, May 15 (Cai Minjie) Guangdong Transportation Group announced on the 15th that at 9 o'clock that day, the Humen Bridge resumed traffic.
On May 5, the suspension bridge of Humen Bridge had obvious vertical bending vibration phenomenon, the bridge management started the emergency plan, and the joint traffic police department took two-way traffic control measures.
On May 6, the expert working group of the Ministry of Transport went to the Humen Bridge on-site for guidance in time. The Guangdong Provincial Department of Transportation and the Provincial Communications Group have successively invited well-known experts in the Mainland to review the comprehensive inspection, detection and safety assessment report of the suspension bridge, analyze and judge the causes of vibration, and discuss the vibration suppression plan.
The bridge manager immediately organized the design, inspection, construction and other units to conduct a comprehensive inspection, detection and safety assessment of the suspension bridge, commissioned three universities to carry out wind resistance research in parallel, and the design unit took the lead to work with the inspection, three universities, and construction units Analyze the causes of vibration and study and demonstrate the measures to suppress vibration.
Guangdong Provincial Transportation Group said that the inspection unit has issued an evaluation report on the structural safety of the suspension bridge of Humen Bridge in the past three years and the inspection and monitoring data. The evaluation shows that the technical status and load-bearing performance of the bridge structure remain stable. The vibration did not affect the structural safety. The key components of the bridge, such as steel box girder, sling, main cable saddle, loose cable saddle, bearing and expansion joints, were not found abnormal. The specially invited expert group, after review, believed that the testing and monitoring items were relatively complete, the methods were reasonable and standardized, and the data were credible. They agreed with the assessment conclusions of the testing unit and the design unit, and the structure of the suspension bridge of the Humen Bridge was safe.
Guangdong Provincial Communications Group said that the specially invited expert group carefully reviewed the analysis of the vibration causes of the suspension bridge and the research report on the vibration suppression measures. The continuous installation of water horses on the side rails of the bridge changes the aerodynamic shape of the steel box girder. Under certain wind conditions, it induces vertical vortex-induced resonance of the suspension bridge; the vortex vibration that lasts for a long time and has a large amplitude causes the bridge structure damping to decrease. Even if the water horse is dismantled, vortex vibration occurs in the no-load bridge under certain wind conditions.
According to the research results and the recommendations of the expert group, the management of the bridge took timely measures to suppress vibration, which mainly included installing dampers on the outer guardrail, improving the aerodynamic shape of the steel box girder, adding water tank weight and increasing the damping ratio. At present, the overall condition of the suspension bridge of Humen Bridge is stable and the vibration suppression effect is good.
On the evening of May 13, at the Humen Bridge Suspension Bridge Restoration Traffic Evaluation Meeting, the invited expert group believed that the Humen Bridge Suspension Bridge is structurally safe and the bridge management has taken vibration suppression measures and implemented the preparations before restoring traffic and agreed to resume traffic operations .
The Humen Bridge is located on the Lion Ocean at the Pearl River Estuary, connecting Nansha District of Guangzhou City and Humen Town of Dongguan City. The main bridge is 4.6 kilometers long and the main span is 888 meters of steel box girder suspension bridge.
According to industry insiders, the main bridge of Humen Bridge was the first large-span steel box girder suspension bridge designed and constructed independently by China. It was the largest modern highway suspension bridge at that time. There were many technological innovations in the history of bridge construction in China. This emergency response to vortex vibration under specific wind conditions will accumulate experience in the design and maintenance of suspension bridges. (Finish)