Experimental Study On Control Of Wind-induced Vibration Of Stay Cables With MR Damper

In Jiangsu and Zhejiang coastal areas,rivers and lakes are well developed,and cablestayed bridges,suspension bridges and other long-span bridges with high wind sensitivity are often recommended for bridge construction.However,the coastal area of Zhejiang Province is also a typhoon prone area.The vibration of the bridge caused by wind loads will accelerate the fatigue damage of the main beam and cables.Magnetorheological dampers for vibration control of stay cables have also been widely used.In this paper,the wind-induced vibration of stay cables is studied by the control test of MR damper.The double sigmoid formula of MR damper is modified,and then a semi-physical simulation test method of cable damper is proposed and compared.The vibration control effect of MR damper on stay cable is studied finally.The main contents and conclusions are as follows:1)The experiment to obtain the performance of MR damper was carried out.The single cable model and the whole bridge model are established by the ANSYS software,and the vibration frequency of the single cable and the cable under the whole bridge model are obtained,thus the reasonable test frequency is determined.The time,output,voltage,rod speed and response time of MR damper are analyzed.2)Several kinds of MR damper models are analyzed,double sigmoid model is selected,and the actual offset effect of the damper is considered to modify the double sigmoid model.The maximum yield force,correlation coefficient before yield,crossing speed and damping coefficient of each working condition are obtained by image recognition.Four parameters mentioned above are fitted as binary equation by taking voltage and piston rod speed as independent variables,and then the offset correlation parameters are obtained by genetic algorithm.3)In order to ensure the authenticity and feasibility of the numerical calculation,the scale naked cable and scale "cable + external damping" are used as the solid test,and the numerical model is established to compare the simulation results.Based on the above tests,a semi-physical simulation model of scale test is established by combining matlab with d SPACE.The vibration data of naked cable are imported at the input end and the test results of "cable + external damping" are exported at the output end.After the verification,the first-order vibration data measured by the real bridge is used as the input data,and the MR damper model is adopted as the additional damping.The output results with and without damper under first-order vibration mode are given,which are compared with the real bridge data with MR damper to verify the feasibility of the semi-physical simulation test in the civil engineering.4)Yanmeng typhoon model is used to fit the typhoon model of Dinghai station in Zhoushan City,Zhejiang Province,and the annual typhoon profile index is calculated as0.109.Based on the above analysis,ANSYS and MATLAB are used to fit the fluctuating wind speed of the three-dimensional typhoon wind field at the bridge site,calculate the internal force time history,analyze the buffeting fatigue analysis of cables under the typhoon.MR damper is then added to the model to analyze the internal force time history of cables with damper under typhoon.The results indicated that the damping has little effect on the vibration damage reduction of stay cables in the middle span of the bridge.