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相对于成桥状态,斜拉桥最大双悬臂施工阶段的刚度低、阻尼小,更容易产生风致振动。建议了一种安装拆卸方便、成本较低的水阻尼器,并进行了CFD仿真分析和减振试验,以验证其抑制斜拉桥施工期风致振动的有效性。结果表明:1水阻尼器能显著增大阻尼系数,减轻结构振动;2过小的开孔率不能有效利用水阻尼器内部流体的黏滞作用来耗能,而过大的开孔率则使得水阻尼器上下游两个表面压力差减小严重;3在靠近水阻尼器两侧位置开孔,会使得外部绕流的旋涡在其两侧脱落;而靠近中心位置的开孔则可以使大漩涡在其下游面上脱落,有利于增大阻力系数;4侧孔对系统阻尼的影响将会随水阻尼器上下游两面开孔的不同而改变,过大或过小的侧面开孔都会显著降低阻尼系数;5水阻尼器体积的增大会降低减振效果,同时还应合理设计水阻尼器的最优的孔隙率,以达到最佳减振效果。综上所述,水阻尼器能有效抑制结构振动,且成本低廉、施工方便,特别适用于某些只需在施工期进行短期风振控制的桥梁。
Relative to the bridge state, the maximum double-suspension cable stayed bridge construction phase of the low stiffness, damping small, more prone to wind-induced vibration. A water damper with convenient installation and disassembly and low cost was proposed. CFD simulation analysis and vibration damping test were also conducted to verify its effectiveness in suppressing wind-induced vibration during the construction of cable-stayed bridges. The results show that: 1 water damper can significantly increase the damping coefficient and reduce the structural vibration; 2 too small opening rate can not effectively use the viscous effect of fluid inside the water damper to consume energy, while the excessively large opening rate makes The pressure difference between the two surfaces on the upstream and downstream of the water damper is reduced severely; 3) the openings near both sides of the water damper cause the vortex of the external flow to fall off on both sides; and the opening near the center can make the large Vortex shedding on its downstream face is conducive to increasing the drag coefficient; 4 side holes on the system damping will vary with the water damper on both sides of the opening on both sides of the hole, too large or too small side openings will be significant Reduce the damping coefficient; 5 increase the volume of water dampers will reduce the damping effect, while the rational design of water dampers should be the optimal porosity to achieve the best damping effect. In summary, the water damper can effectively suppress the structural vibration, and has the advantages of low cost and convenient construction, and is particularly suitable for some bridges which need only short-term wind-induced vibration control during the construction period.