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
A core-shell model that accounts for surface effects is suggested to investigate the postbuckling behavior of nanowires.The corresponding critical load,buckling wavenumber and amplitude incorporated in the surface eff...A core-shell model that accounts for surface effects is suggested to investigate the postbuckling behavior of nanowires.The corresponding critical load,buckling wavenumber and amplitude incorporated in the surface effects are analytically derived.The results demonstrate that the surface effects have a strong influence on the buckling amplitude of each order.This study can not only shed light on the postbuckling of nannowires but also provide an method for measuring the physical parameters of nanowires used in nano-devices.展开更多
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Supported by the National Natural Science Foundation of China under Grant No 51078041the open foundation of the Key Laboratory of Highway Engineering under grant No kfj080108.
文摘A core-shell model that accounts for surface effects is suggested to investigate the postbuckling behavior of nanowires.The corresponding critical load,buckling wavenumber and amplitude incorporated in the surface effects are analytically derived.The results demonstrate that the surface effects have a strong influence on the buckling amplitude of each order.This study can not only shed light on the postbuckling of nannowires but also provide an method for measuring the physical parameters of nanowires used in nano-devices.
