A finite element vibration model of a multiple wheel-rail system which consists of four wheels, one rail, and a series of sleepers is established to address the problem of rail corrugation in high-speed tracks. In the...A finite element vibration model of a multiple wheel-rail system which consists of four wheels, one rail, and a series of sleepers is established to address the problem of rail corrugation in high-speed tracks. In the model, the creep forces between the wheels and rail are considered to be saturated and equal to the normal contact forces times the friction coefficient. The oscillation of the rail is coupled with that of wheels in the action of the saturated creep forces. When the coupling is strong, self- excited oscillation of the wheel-rail system occurs. The self-excited vibration propensity of the model is analyzed using the complex eigenvalue method. Results show that there are strong propensities of unstable self-excited vibrations whose frequencies are less than 1,200 Hz under some conditions. Preventing wheels from slipping on rails is an effective method for suppressing rail corrugation in high-speed tracks.展开更多
文章以安吉曙光桥为例,研究了这座双层桥面斜腿刚构连续梁桥的人致振动及减振设计。计算了桥梁的行人荷载及动力特性,分析了该桥的人致振动响应并进行舒适度评价。针对桥梁双层布置的特点,提出了应用连杆提高刚度、应用调谐质量阻尼器(T...文章以安吉曙光桥为例,研究了这座双层桥面斜腿刚构连续梁桥的人致振动及减振设计。计算了桥梁的行人荷载及动力特性,分析了该桥的人致振动响应并进行舒适度评价。针对桥梁双层布置的特点,提出了应用连杆提高刚度、应用调谐质量阻尼器(Tuned Mass Damper,TMD)增强阻尼的减振设计思路,比较分析了3种不同的减振设计:单独设置TMD、单独设置连杆、联合设置连杆-TMD。研究结果表明:安吉曙光桥振动频率低、人致振动响应较大,需对其进行减振控制;单独布置TMD,可有效控制桥梁的振动响应;单独设置2组连杆,可显著提高桥梁的自振频率;同时设置连杆和TMD,可采用较小的TMD实现减振目标。3种减振设计均能满足舒适度要求,工程中应根据实际情况选用。展开更多
One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrat...One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrations of a structure with variable friction damper using a new Bang-Bang control input. A continuous function of story velocities is used to represent the improved control to reduce chatter, high frequency switching and avoid instability. With a genetic algorithm, the amplitudes of control and preloading friction forces individually prescribed in the controller and damper are optimized for enhancing the seismic performance of buildings. The control strategy for the friction damper is proposed for a three story building with one variable friction damper installed at the first story for seismic reduction. The numerical results indicate that a better reduction of peak response accelerations of floors can be achieved than those of the unmodified controller, and the adaptability of the control system is also improved greatly by comparison with the reduction ratios of the structural response energy excited by different earthquake intensities.展开更多
基金supported by the National Natural Science Foundation of China(No.51275429)
文摘A finite element vibration model of a multiple wheel-rail system which consists of four wheels, one rail, and a series of sleepers is established to address the problem of rail corrugation in high-speed tracks. In the model, the creep forces between the wheels and rail are considered to be saturated and equal to the normal contact forces times the friction coefficient. The oscillation of the rail is coupled with that of wheels in the action of the saturated creep forces. When the coupling is strong, self- excited oscillation of the wheel-rail system occurs. The self-excited vibration propensity of the model is analyzed using the complex eigenvalue method. Results show that there are strong propensities of unstable self-excited vibrations whose frequencies are less than 1,200 Hz under some conditions. Preventing wheels from slipping on rails is an effective method for suppressing rail corrugation in high-speed tracks.
文摘文章以安吉曙光桥为例,研究了这座双层桥面斜腿刚构连续梁桥的人致振动及减振设计。计算了桥梁的行人荷载及动力特性,分析了该桥的人致振动响应并进行舒适度评价。针对桥梁双层布置的特点,提出了应用连杆提高刚度、应用调谐质量阻尼器(Tuned Mass Damper,TMD)增强阻尼的减振设计思路,比较分析了3种不同的减振设计:单独设置TMD、单独设置连杆、联合设置连杆-TMD。研究结果表明:安吉曙光桥振动频率低、人致振动响应较大,需对其进行减振控制;单独布置TMD,可有效控制桥梁的振动响应;单独设置2组连杆,可显著提高桥梁的自振频率;同时设置连杆和TMD,可采用较小的TMD实现减振目标。3种减振设计均能满足舒适度要求,工程中应根据实际情况选用。
基金The project supported by the National Science Fund for Distinguished Young Scholars(50025823).
文摘One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrations of a structure with variable friction damper using a new Bang-Bang control input. A continuous function of story velocities is used to represent the improved control to reduce chatter, high frequency switching and avoid instability. With a genetic algorithm, the amplitudes of control and preloading friction forces individually prescribed in the controller and damper are optimized for enhancing the seismic performance of buildings. The control strategy for the friction damper is proposed for a three story building with one variable friction damper installed at the first story for seismic reduction. The numerical results indicate that a better reduction of peak response accelerations of floors can be achieved than those of the unmodified controller, and the adaptability of the control system is also improved greatly by comparison with the reduction ratios of the structural response energy excited by different earthquake intensities.
