| Cable stayed bridge is combined system bridge composed of three basic load-bearing components, including beam(deck), tower, and stay-cables both ends respectively anchoring on the beam and the tower. With its good stress performance, structural diversity, strong seismic resistance capability, maturity of construction method and so on, it becomes the fastest growing, most widely used and one of the most competitive bridge type in modern large-span bridge engineering. But, due to the small mass, stiffness and damping of stay-cables on cable stayed bridge, as well as the increased slenderness ratio caused by growth span of cable stayed bridge, the influence of stay-cable vibration problem is becoming more and more significant, causing harm to the safety of the bridge structure. Compared with traditional types of vibration, rain-wind induced vibration and dry cable galloping have larger amplitude and bring about stronger damage, which need to be studied deeply.In order to analysis the mechanism of dry cable galloping from the perspective of Reynolds number effect, the paper uses smooth stay-cable model and stay-cable models with different surface roughness to change the intensity of Reynolds number effect and the range of critical Reynolds number, and tests the vibration of rigid models in wind tunnel.First of all, the paper introduces the main wind-induced vibration types of stay-cables and the research background in general, and also summarizes two-dimensional flow around cylinder which is a classic pattern and the abstraction from the flow state of stay-cables in wind field.Secondly, through the aspects of fluid similarity and model making, the reliability of wind tunnel test on stay-cable vibration is discussed. The paper also introduces how to quantitatively describe the surface roughness, and records the details of test process, including model manufacture and installation, equipments used along the test, test content, and controlling Reynolds numbers as well as its steps of each working condition and so on.Finally, the paper analyses test results of smooth stay-cable model and stay-cable models with different surface roughness, then obtains the rule of the stay-cable models vibration amplitude and equilibrium position changing with the Reynolds number. Then it analyses the mechanism of dry cable galloping from the perspective of Reynolds number effect, in the region of critical Reynolds number, lift coefficient and the changement characteristics of the flow field may cause large-amplitude stay-cable vibration, it could be the vibration mechanism of dry cable galloping. |
PDF Full Text Request