In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limita...In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.展开更多
The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this...The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1：100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.展开更多
Pendulum-type ( μ wave) wave is a new type of elastic wave propagated with low frequency and low velocity in deep block rock masses. The μ wave is sharply different from the traditional longitudinal and transverse w...Pendulum-type ( μ wave) wave is a new type of elastic wave propagated with low frequency and low velocity in deep block rock masses. The μ wave is sharply different from the traditional longitudinal and transverse waves propagated in continuum media and is also a phenomenon of the sign-variable reaction of deep block rock masses to dynamic actions, besides the Anomalous Low Friction (ALF) phenomenon. In order to confirm the existence of the μ wave and study the rule of variation of this μ wave experimentally and theoretically, we first carried out one-dimensional low-speed impact experiments on granite and cement mortar blocks and continuum block models with different characteristic dimensions, based on the multipurpose testing system developed by us independently. The effects of model material and dimensions of models on the propagation properties of 1D stress wave in blocks medium are discussed. Based on a comparison and analysis of the propagation properties (acceleration amplitudes and Fourier spectra) of stress wave in these models, we conclude that the fractures in rock mass have considerable effect on the attenuation of the stress wave and retardarce of high frequency waves. We compared our model test data with the data of in-situ measurements from deep mines in Russia and their conclusions. The low-frequency waves occurring in blocks models were validated as Pendulum-type wave. The frequencies corresponding to local maxima of spectral density curves of three-directional acceleration satisfied several canonical sequences with the multiple of 2～(1/2), most of those frequencies satisfied the quantitative expression (2～(1/2))i V p/2△ .展开更多
针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的...针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的恢复力计算公式,进行拟静力试验,设计装置在隔震桥梁中的布置方式,给出了在SAP2000中实现RMFD装置恢复力模型的方法,利用MATLAB和SAP2000对同一单自由度结构的响应进行对比,验证了方法的有效性。进而以某一6跨连续摩擦摆隔震桥梁为研究对象,利用SAP2000软件对比分析大震下非隔震桥梁、摩擦摆隔震桥梁以及RMFD限位摩擦摆隔震桥梁的地震响应、减震率、支座位移控制效果,以及等效摩擦力变化时墩柱响应峰值、减震率及墩柱损伤状态的变化情况。结果表明:RMFD作为桥梁隔震限位装置,仅需要较小的螺栓预紧力即可获得较大的RMFD阻尼器出力,位移行程大、耗能能力强,能够有效地将隔震层的位移控制在允许范围之内,避免支座位移超限引起的落梁、碰撞等震害的发生;同时,桥墩的墩底剪力、墩顶位移等地震反应稍有增大,减震率有所降低,但降幅均在10%以内,隔震桥梁仍具有良好的减震效果;随着等效摩擦力的增大,墩顶位移、墩底剪力、墩底弯矩最大值均不断增大,但支座的位移逐渐减小,说明螺栓预紧力越大,隔震层的位移控制效果越好,但其余地震响应的控制效果变差,桥墩损坏程度会加大,因此应合理设计预紧力的大小以取得理想的减震效果。展开更多
基金Area Strategic Development Program inStructural Control and Intelligent Building from The HongKong Polytechnic University, and National Natural SciencFoundation of China Under Grant No. 50408011
文摘In this paper, wind-induced vibration control of a single column tower of a cable-stayed bridge with a multi- stage pendulum mass damper （MSPMD） is investigated. Special attention is given to overcoming space limitations for installing the control device in the tower and the effect of varying natural frequency of the towers during construction. First, the finite element model of the bridge during its construction and the basic equation of motion of the MSPMD are introduced. The equation of motion of the bridge with the MSPMD under along-wind excitation is then established. Finally, a numerical simulation and parametric study are conducted to assess the effectiveness of the control system for reducing the wind-induced vibration of the bridge towers during construction. The numerical simulation results show that the MSPMD is practical and effective for reducing the along-wind response of the single column tower, can be installed in a small area of the tower, and complies with the time-variant characteristics of the bridge during its entire construction stage.
基金Area Strategic Development Program in Structural Control and Intelligent Building from The Hong Kong Polytechnic UniversityNational Natural Science Foundation of China Under Grant No. 50408011
文摘The possibility of using a multi-stage pendulum mass damper （MSPMD） to control wind-induced vibration of a single column tower of a cable-stayed bridge during construction was studied theoretically in part I of this work. In this paper, the performance of the MSPMD for reducing bridge tower vibration is studied experimentally. A MSPMD model and a tower model of the bridge with geometry scaling of 1：100 were designed and manufactured. Calibration of the MSPMD model with different wire lengths is conducted to verify the analytical model of the damper. A series of tests for the uncontrolled freestanding tower, tower with cables, and tower with MSPMD model are then performed under harmonic and white noise excitations. The experimental results show that the responses of the tower model significantly decrease with the installation of the MSPMD model, which demonstrates the effectiveness of the M SPMD to mitigate the vibration of the bridge tower.
基金Projects 50525825 and 90815010 supported by the National Natural Science Foundation of China2009CB724608 by the National Basic Research Program of ChinaBK2008002 by the Natural Science Foundation of Jiangsu Province
文摘Pendulum-type ( μ wave) wave is a new type of elastic wave propagated with low frequency and low velocity in deep block rock masses. The μ wave is sharply different from the traditional longitudinal and transverse waves propagated in continuum media and is also a phenomenon of the sign-variable reaction of deep block rock masses to dynamic actions, besides the Anomalous Low Friction (ALF) phenomenon. In order to confirm the existence of the μ wave and study the rule of variation of this μ wave experimentally and theoretically, we first carried out one-dimensional low-speed impact experiments on granite and cement mortar blocks and continuum block models with different characteristic dimensions, based on the multipurpose testing system developed by us independently. The effects of model material and dimensions of models on the propagation properties of 1D stress wave in blocks medium are discussed. Based on a comparison and analysis of the propagation properties (acceleration amplitudes and Fourier spectra) of stress wave in these models, we conclude that the fractures in rock mass have considerable effect on the attenuation of the stress wave and retardarce of high frequency waves. We compared our model test data with the data of in-situ measurements from deep mines in Russia and their conclusions. The low-frequency waves occurring in blocks models were validated as Pendulum-type wave. The frequencies corresponding to local maxima of spectral density curves of three-directional acceleration satisfied several canonical sequences with the multiple of 2～(1/2), most of those frequencies satisfied the quantitative expression (2～(1/2))i V p/2△ .
文摘针对现有隔震桥梁限位装置以及摩擦阻尼器存在的不足,利用机械领域常用的滚珠丝杠提出一种具有响应放大和负刚度效应的新型旋转质量摩擦阻尼器(Rotational Mass Friction Damper,RMFD)限位装置,介绍该装置的构造及作用机理,推导装置的恢复力计算公式,进行拟静力试验,设计装置在隔震桥梁中的布置方式,给出了在SAP2000中实现RMFD装置恢复力模型的方法,利用MATLAB和SAP2000对同一单自由度结构的响应进行对比,验证了方法的有效性。进而以某一6跨连续摩擦摆隔震桥梁为研究对象,利用SAP2000软件对比分析大震下非隔震桥梁、摩擦摆隔震桥梁以及RMFD限位摩擦摆隔震桥梁的地震响应、减震率、支座位移控制效果,以及等效摩擦力变化时墩柱响应峰值、减震率及墩柱损伤状态的变化情况。结果表明:RMFD作为桥梁隔震限位装置,仅需要较小的螺栓预紧力即可获得较大的RMFD阻尼器出力,位移行程大、耗能能力强,能够有效地将隔震层的位移控制在允许范围之内,避免支座位移超限引起的落梁、碰撞等震害的发生;同时,桥墩的墩底剪力、墩顶位移等地震反应稍有增大,减震率有所降低,但降幅均在10%以内,隔震桥梁仍具有良好的减震效果;随着等效摩擦力的增大,墩顶位移、墩底剪力、墩底弯矩最大值均不断增大,但支座的位移逐渐减小,说明螺栓预紧力越大,隔震层的位移控制效果越好,但其余地震响应的控制效果变差,桥墩损坏程度会加大,因此应合理设计预紧力的大小以取得理想的减震效果。
