Abstract
Steel truss stiffening girders are widely used when designing long-span bridges in mountainous areas owing to their distinct characteristics compared to the streamlined box girder. However, natural wind in mountainous areas is very complex with high turbulence and large attack angles which adversely affect the flutter performance of long-span bridges with truss girders. Aerodynamic countermeasures are widely adopted to improve flutter performance. This paper studies the flutter performance and the effects of various aerodynamic countermeasures on the flutter improvement of a 1060 m truss-stiffened girder suspension bridge spanning mountainous canyon by wind tunnel tests of the sectional model and full-bridge model. First, sectional model tests with the original girder section were carried out under various wind attack angles. Subsequently, to improve the flutter stability of the bridge under the most unfavorable wind attack angle, several aerodynamic countermeasures including central upper stabilizer, horizontal stabilizer, combined central upper and horizontal stabilizers, and sealed central traffic barrier were proposed and sectional model tests with optimized girders were conducted. The results show that the aerodynamic mitigation effect of the central upper stabilizer, horizontal stabilizer, as well as combined measure, is closely related to the geometric dimension of the stabilizing plate. It is found that large geometric dimensions effectively increase the flutter critical wind speed of the truss girder. Considering sealed central traffic barrier measure, the smaller ventilation rates result in larger flutter critical wind speed of the girder. The sealed central traffic barrier measure with a 50 % ventilation rate is deemed as the most optimal aerodynamic countermeasure in consideration of aesthetics, economy, and safety. Finally, the effectiveness of optimal countermeasure is validated through an aeroelastic full-bridge model test. The research is conducted to provide references on flutter performance optimization of similar bridges in the future.
Highlights
Over the past few decades, the rapid progress in bridge aerodynamics and construction techniques have enabled long-span suspension bridges to achieve remarkable main span lengths
Streamlined box girder owing to its distinct characteristics such as lightweight, less steel consumption, excellent flutter stability, and reduced aerodynamic drag force has been adopted for several bridges
By comparing the test results of various cases of the above flutter countermeasures from the perspective of construction feasibility, flutter code requirements, and economy, it can be observed that Case 11 which is a sealed central traffic barrier with a 50 % ventilation rate is the optimal aerodynamic optimization measure of the bridge against the most unfavorable wind attack angle (i.e., +3°)
Summary
Over the past few decades, the rapid progress in bridge aerodynamics and construction techniques have enabled long-span suspension bridges to achieve remarkable main span lengths. To improve the flutter performance of the Akashi-Kaikyo Bridge, several aerodynamic countermeasures were proposed This resulted in a lower central vertical stabilizer with a 2.15 m height in combination with open grating provided in the center and on both sides of the truss girder [15]. The flutter performance of a steel truss-stiffened girder suspension bridge in a mountainous canyon and the influence of various aerodynamic countermeasures on the improvement of flutter stability using wind tunnel tests of the sectional model and full-bridge model was studied. To improve the flutter stability of the bridge girder against the most unfavorable wind attack angle of +3°, a series of aerodynamic optimization measures including the central upper stabilizer, horizontal stabilizer, combined countermeasures, and sealed central traffic barrier were considered and sectional model tests with modified sections were conducted. The results of sectional model tests were verified with the full-bridge aeroelastic model test
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
