TVMD(Tuned Viscous Mass Damper)是一种能将实际质量放大上千倍,且能利用惯性力和调谐效应的新型减振装置。为有效提升连续梁桥的减震效果,研究采用空间分布的TVMD实现连续梁减震的优化设计和高效性能。先以TVMD对单自由度结构减震为例...TVMD(Tuned Viscous Mass Damper)是一种能将实际质量放大上千倍,且能利用惯性力和调谐效应的新型减振装置。为有效提升连续梁桥的减震效果,研究采用空间分布的TVMD实现连续梁减震的优化设计和高效性能。先以TVMD对单自由度结构减震为例,探究TVMD在调谐频率处的高阻尼效应,及其附加刚度对结构动力特征的影响机制,揭示针对多个TVMD开展同步设计的必要性;进而建立连续梁桥多自由度精细模型,采用基于H2性能的梯度优化法实现多个TVMD的参数优化;分别基于连续梁桥纵、横向减震时的典型状态,实现空间分布且可能对多阶模态调谐的TVMD的优化设计,就连续梁桥的稳态谐振响应以及不同谱特性的地震波输入时的地震响应开展减震分析,阐明了TVMD相对于VD(Viscous Damper)减震时的高效性能。展开更多
To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristi...To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.展开更多
Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectiona...Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectional models of the girder and trains were employed for aerodynamic force measurement and VIV test,respectively.Results indicate that the aerodynamic interference effect on static aerodynamic forces of both the girder and trains is remarkable.When a single train exists,the horizontal position of the train has a small effect on aerodynamic coefficients of the girder.When two trains meet on the girder,the drag coefficient of the girder is significantly reduced compared with that of without train or with a single train;besides,during the whole meeting process,aerodynamic forces of the leeward train first drop and then increase suddenly.The fluctuation of aerodynamic force could cause redundant vibration of the train,which is unfavorable for safety and comfort.A train on the girder could worsen the girder VIV performance:a new vertical VIV appears in the triple-box girder when a train is on the girder,and the torsional VIV amplitude increases significantly when the train is on the windward side.展开更多
文摘TVMD(Tuned Viscous Mass Damper)是一种能将实际质量放大上千倍,且能利用惯性力和调谐效应的新型减振装置。为有效提升连续梁桥的减震效果,研究采用空间分布的TVMD实现连续梁减震的优化设计和高效性能。先以TVMD对单自由度结构减震为例,探究TVMD在调谐频率处的高阻尼效应,及其附加刚度对结构动力特征的影响机制,揭示针对多个TVMD开展同步设计的必要性;进而建立连续梁桥多自由度精细模型,采用基于H2性能的梯度优化法实现多个TVMD的参数优化;分别基于连续梁桥纵、横向减震时的典型状态,实现空间分布且可能对多阶模态调谐的TVMD的优化设计,就连续梁桥的稳态谐振响应以及不同谱特性的地震波输入时的地震响应开展减震分析,阐明了TVMD相对于VD(Viscous Damper)减震时的高效性能。
基金Projects(20B062,19B054)supported by Excellent Youth Program of Hunan Education Department,ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation of ChinaProject(kq195004)supported by Changsha Science and Technology Bureau Project,China。
文摘To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.
基金Project(52025082) supported by the National Natural Science Foundation for Distinguished Young Scholars of ChinaProject(CX20190288) supported by Hunan Provincial Innovation Foundation for Postgraduate,China。
文摘Wind tunnel tests were carried out to investigate the aerodynamic interference between a triple-box girder and trains,involving static aerodynamic forces and vortex-induced vibrations(VIVs).Static and dynamic sectional models of the girder and trains were employed for aerodynamic force measurement and VIV test,respectively.Results indicate that the aerodynamic interference effect on static aerodynamic forces of both the girder and trains is remarkable.When a single train exists,the horizontal position of the train has a small effect on aerodynamic coefficients of the girder.When two trains meet on the girder,the drag coefficient of the girder is significantly reduced compared with that of without train or with a single train;besides,during the whole meeting process,aerodynamic forces of the leeward train first drop and then increase suddenly.The fluctuation of aerodynamic force could cause redundant vibration of the train,which is unfavorable for safety and comfort.A train on the girder could worsen the girder VIV performance:a new vertical VIV appears in the triple-box girder when a train is on the girder,and the torsional VIV amplitude increases significantly when the train is on the windward side.
