The Wind-induced Vibration Response And Control Of Stayed-cable

Stay cable is one of the main components in cable—stayed bridge. The structure has large span, light weight, small damp and low natural vibration frequency, and easily occurred vibration under wind load. The wind load for cable structure is a very important source of excitation. It is necessary to calculate and analyze the structure's wind-induced vibration response and control the response effectively. It has major significance for design and construction of the cable-stayed bridge.At present, the wind-resistant design for cable-stayed structures is mainly based on the wind tunnel test and field measurement. The two methods can obtain accurate wind load sample, but are very expensive and have long test cycle. For the shortcomings of both methods, this paper is based on Auto-Regressive Method in random vibration theory. The method which is used in rigid structure surface wind speed and wind load simulation method is extended to a large flexibility structural surface winds simulation. A high efficiency and high precision simulation method is obtained for fluctuating wind speed of large flexibility structure. According to the need of wind calculation, the velocity time-history is transformed into load time-history. Wind speed programs changed with height are compiled by MATLAB language. The simulated wind load is applied to the surface of cables which is based on the establishment of the SAP2000 finite element environment. The time history on the cable structure is analyzed and the structure vibration is obtained.As the structure has large wind-induced vibration, viscous dampers are used to control the vibration. In this paper, the oil dampers are adopted to increase the modal damping of cable. The result showed that the control joint displacement has apparent control effect by the use of oil dampers.Finally, a three-dimensional cable with the cable sag effect the modal damping ratio is studied. These parameters include the cable angle, cable sag, damping coefficient and damper angle. The results showed that with the increase of cable angle, the modal damping ratio is increase. When the sag parameter lgλ2≤1.5,with the sag parameter is increases, the modal damping ratio is decrease. With the connection point distance from the anchor is increase; the modal damping ratio is also increase.