| With the increase of the span of the cable-stayed bridge,the stay cable is developing in the direction of low damping,light weight and small stiffness.The stay cable is prone to various types of wind-induced vibration under the action of wind load,among which the rain-wind vibration is the most harmful.In order to suppress the windrain vibration of stay cables,aerodynamic suppression measures are often used.Setting the longitudinal ribs as one of the aerodynamic suppression measures to suppress the rain-wind vibration of the stay cable can suppress the vibration by preventing the formation of the waterline.However,in practical engineering,it is found that in addition to wind-rain vibration,vortex-induced vibration often occurs in stay cables at low wind speed,which is easy to cause fatigue damage of structures.Whether the longitudinal ribs used to suppress rain-wind vibration can suppress vortex-induced vibration and how the aerodynamic characteristics of stay cables with additional longitudinal ribs change are very concerned in wind-resistant design.Through the pressure measurement,force measurement and vortex-induced vibration test in the wind tunnel,the variation law of aerodynamic force and vortex-induced vibration of stay cable under different rib position,number,wind attack angle,length and shape are studied respectively.The main conclusions are as follows:(1)At different positions of the ribs,with the increase of the rib position,the Reynolds number effect of the aerodynamic coefficient and the wind pressure coefficient of the stay cable gradually disappears.For vortex-induced vibration,when the arrangement of the ribs is at 55°,the vortex-induced vibration of the stay cable is completely suppressed,but when the arrangement of the ribs is at 60°,the vortexinduced vibration wind speed lock interval of the stay cable will be enlarged.(2)Under the different number of ribs,the average drag coefficient of the stay cables with two ribs and three ribs decreases first at a small wind attack angle.At a large wind attack angle,the change of the stay cables with 4,6,8 and 12 ribs are consistent,and the increase of Reynolds number has no effect on the aerodynamic coefficient.For vortex-induced vibration,for 2,3 and 12 ribs,the ribs significantly reduce the maximum amplitude,and for 4,6 and 8 ribs,the change of the maximum amplitude is not obvious.(3)Under the rib size of 5 mm thickness,the rib shape is no longer a significant factor affecting fluid separation;compared with the full-length ribs,the partial-length ribs significantly reduce the variation range of the aerodynamic force of the stay cable. |
