【作者】 戴军；

【导师】 徐赵东； Shirley J. Dyke； 尹学军；

【作者基本信息】 东南大学 ， 防灾减灾工程及防护工程， 2020， 博士

【摘要】 桥梁涡激振动是一种由气流绕经主梁表面产生周期性脱落漩涡而导致的主梁竖向或者扭转振动,当脱落漩涡的频率接近桥梁的某阶自振频率时,桥梁便产生涡激共振现象。尽管涡激共振不像颤振一样使桥梁发生毁灭性破坏,但其低风速下的高发生概率、大振动幅值等特点严重影响大跨桥梁的行车安全、舒适度和构件的疲劳性能。调谐质量阻尼器(TMD)被广泛地应用于桥梁涡激振动的抑制,TMD通过调谐机制将主梁的动能转移到自身,并通过阻尼单元以内能形式耗散,从而达到抑制桥梁涡激振动的目的。由于忽略涡激振动的非线性和不确定性,用于抑制桥梁涡激振动的TMD在参数选取、效果评估、行程限制、鲁棒性等问题上并没有得到系统的研究。本文以港珠澳大桥深水区非通航孔桥为工程背景,开展“港珠澳大桥深水区非通航孔桥TMD风致振动控制”的研究。风洞试验结果表明,该桥在设计风速内会发生一阶竖弯涡激共振,最大幅值超过规范限值,故采用TMD抑制深水区非通航孔桥的涡激共振。本文在既有TMD方案的基础上,以提高TMD抑振鲁棒性为主要目标,提出了TMD参数设计和抑振效果评估方法,采用了粘弹性TMD抑制桥梁的涡激共振,并开展了一系列的试验与理论研究。主要研究内容和结论如下:(1)TMD抑制港珠澳大桥非通航孔桥涡激共振港珠澳大桥深水区非通航孔桥风洞试验表明,当实桥风速达到27m/s-35m/s时,主梁产生幅值达150mm的竖向涡激共振,需采用TMD抑振;采用Krylov Bogoliubov方法推导出TMD贡献的等效阻尼比,其大小仅与TMD的设计参数相关,且设计参数影响了涡激共振频率;桥梁的涡激共振幅值对气动参数敏感,TMD贡献阻尼比对桥梁模态参数敏感;提出了TMD涡激共振抑制失效概率,并基于该失效概率比较了三种常用TMD参数设计公式;深水区非通航孔桥实测结果表明,布置TMD后桥梁的第一模态阻尼比由0.65%增加到2.11%。(2)粘弹性TMD力学性能试验介绍了粘弹性TMD的构造和耗能原理,对粘弹性TMD各部件进行了力学性能试验。结果表明,改变集中质量位置和粘弹性阻尼层厚度,可实现粘弹性悬臂梁自振频率和阻尼比的调节;钢球半径越大、粘弹性阻尼层厚度越小、碰撞前速度越大,粘弹性阻尼层-钢恢复系数越小;粘弹性TMD在调谐和失调下均能有效抑制悬臂梁的自由振动。(3)粘弹性TMD力学模型根据Oberst梁理论,粘弹性阻尼悬臂梁可以等效为具有复刚度性质的均质梁,提出的基于能量原理的力学模型可以较为准确地估算出设有集中质量的阻尼悬臂梁的模态参数。提出的基于加速度测量的碰撞刚度识别策略可以准确地识别出粘弹性阻尼层-钢之间的碰撞刚度,识别出的Hunt-Crossley模型可以应用到粘弹性TMD抑振当中,获得的仿真效果与试验结果基本一致。(4)简谐力荷载下粘弹性TMD抑振分析建立结构-粘弹性TMD系统在三种状态下的运动方程;进行了结构-双TMD系统、结构-碰撞TMD系统、结构-粘弹性TMD系统的抑振仿真。仿真结果分析表明,双TMD中次TMD的调谐吸能替代了TMD阻尼单元的耗能;碰撞TMD在调谐耗能和碰撞耗能之间存在最优的比例分配或者平衡状态;粘弹性TMD的抑振有效性随着碰撞间隙的减小而下降,而抑振鲁棒性和行程控制随之提高。(5)粘弹性TMD抑制港珠澳大桥非通航孔桥涡激共振建立桥梁-多重粘弹性TMD-涡激力系统的运动方程;采用Krylov Bogoliubov方法推导出了多重双TMD和多重TMD贡献的等效阻尼比,发现多重双TMD和多重TMD可以有效提高贡献阻尼比的鲁棒性。采用粘弹性TMD抑制港珠澳大桥深水区非通航孔桥涡激共振,结果发现,粘弹性TMD具有更大的等效刚度和等效阻尼,且碰撞间隙越小,碰撞越剧烈,最优频率比越小于1;粘弹性TMD仍以调谐吸能为主,碰撞耗能为辅;相比TMD或者多重TMD,粘弹性TMD或者多重粘弹性TMD可以在更宽的失调范围内有效抑制桥梁涡激共振,且质量行程更小。本文的创新主要体现在:(1)提出具有多耗能模式的粘弹性TMD,用来抑制港珠澳大桥深水区非通航孔桥的涡激共振,通过数值仿真验证了该粘弹性TMD相比传统TMD具有更好的抑制鲁棒性和更小的质量行程。(2)基于Krylov Bogoliubov方法推导出的TMD贡献阻尼比和风洞试验识别的气动参数,提出了TMD抑制大跨桥梁涡激共振的失效概率,利用该失效概率可实现TMD的参数优化和评估涡激共振抑制效果。(3)提出了多重粘弹性TMD的贡献阻尼比,基于该贡献阻尼比进行了多重粘弹性TMD的参数优化和大跨度桥梁-多重粘弹性TMD-非线性涡激力的动力时程分析,实现了最优多重粘弹性TMD涡激共振抑制。更多还原

【Abstract】 When the wind flows past a bridge deck,the periodic vortex-shedding occurs and then causes the bridge deck experience a vortex-induced vibration(VIV)with a vertical bending mode or torsional mode.If the vortex shedding frequency approaches to a natural frequency of the bridge deck,the bridge deck will experience a vortex-induced resonance.Although the resonance is not catastrophic as the flutter,it greatly impacts serviceability and driving comfort due to the high likelihood and large amplitude.The tuned mass damper(TMD)is widely used to mitigate the VIV in bridges through absorbing and dissipating the vibration energy from the bridge.However,the parameter design,control effect evaluation,stroke limitation,and robustness of the TMD have not been well studied due to ignoring the nonlinearity and uncertainty of the VIV.Taking the Hong Kong-Zhuhai-Macao Bridge Deep-Water Non-Navigable Bridge as the engineering object,this thesis investigates the VIV mitigation using the TMD.Wind tunnel tests showed that the bridge will experience a large-amplitude vortex-induced resonance with the first vertical bending mode within design wind speeds,and the TMD scheme was adopted for VIV mitigation.Based on the robustness,a design framework of the TMD control,including the parameter design and control effect evaluation,is proposed.Furthermore,a novel viscoelastic TMD is proposed to improve the VIV mitigation of the bridge,and corresponding experimental and theoretical studies are performed.The main research work and conclusions are listed below:(1)The VIV mitigation of the Hong Kong-Zhuhai-Macao Bridge Deep-Water Non-Navigable Bridge using the TMDWind tunnel tests of the Hong Kong-Zhuhai-Macao Bridge Deep-Water Non-Navigable Bridge showed that the girder will experience a vertical vortex-induced resonance with 150 mm amplitude when the wind speed is between 27 m/s and 35 m/s,and TMDs are used to mitigate this VIV.The equivalent damping ratio contributed by TMDs is derived using the Krylov Bogoliubov method,and it depends on the TMD parameters,which influence the vortex-induced resonance frequency.The vortex-induced amplitude is sensitive to the aerodynamic parameters,while the equivalent damping ratio is sensitive to the modal parameters of the bridge.Three typical design formulas for the TMD are compared based on the proposed probability of failure.Filed test results showed that the damping ratio of the first mode of the bridge is improved from 0.65% to 2.11% after installing TMDs.(2)Performance tests of the viscoelastic TMDThe configuration and energy consumption principle of the viscoelastic TMD are introduced.The mechanical performance tests of main components are performed.Test results showed that the natural frequency and damping ratio of the cantilever beam can be adjusted by changing the lumped mass position and viscoelastic layer thickness.The larger the steel ball radius,or the thinner the viscoelastic layer,or the greater the collision velocity,the smaller the coefficient of restitution of the viscoelastic layer-steel collision.The viscoelastic TMD can effectively suppress the free vibration both in the well-tuned and mis-tuned cases.(3)Mechanical model of the viscoelastic TMDAccording to the Oberst beam theory,the viscoelastic cantilever beam can be considered as a homogeneous beam with a sectional complex stiffness.The proposed mechanical model based on the energy theory can be used to estimate the modal parameters of the viscoelastic cantilever beam with a lumped mass.The proposed strategy based on acceleration measurements can identify the pounding stiffness of the viscoelastic layer-steel collision.The identified Hunt-Crossley model can be applied into the viscoelastic TMD control,and the simulation results are basically consistent with the experimental results.(4)The vibration suppression analysis of the viscoelastic TMD.The equations of motion of the structure-viscoelastic TMD system in the three working modes are established.Numerical simulations of the structure-DTMD,pounding TMD,and viscoelastic TMD systems under the harmonic force were performed,respectively.The analysis indicates that the secondary TMD in the DTMD plays a role as the damping element in the TMD;there is an optimal proportion between the tuning and collision in the pounding TMD;the effectiveness of the viscoelastic TMD decreases with the decrease in the gap,but the robustness and stroke limitation are improved.(5)The VIV mitigation of the Hong Kong-Zhuhai-Macao Bridge Deep-Water Non-Navigable Bridge using the viscoelastic TMD.The equations of motion of the bridge-multiple viscoelastic TMD system under the VIV are established.The equivalent damping ratios contributed by the MDTMD or MTMD are derived using the Krylov Bogoliubov method.The result shows that the MDTMD and MTMD have better robustness than the DTMD and TMD.The viscoelastic TMD is used to mitigate the VIV in the Deep-Water Non-Navigable Bridge.The numerical results show that the viscoelastic TMD has larger equivalent stiffness and damping due to the collision than the TMD.The smaller the gap,the more violent the collision,the smaller the optimal frequency ratio.The control effect of the viscoelastic TMD is still dominated by the tuning,supplemented by the collision in the VIV mitigation.The single or multiple viscoelastic TMD has better control effect and stroke limitation than the single or multiple TMD in the mis-tuning cases.The innovations of this paper are listed below:(1)A novel viscoelastic TMD with multiple energy consumption modes is proposed to mitigate the VIV in the Hong Kong-Zhuhai-Macao Bridge Deep-Water Non-Navigable Bridge,and its better control robustness and stroke limitation capability than the TMD are validated by numerical simulations.(2)According to the damping ratio contributed by the TMD and the aerodynamic parameters identified from wind tunnel tests,a probability of failure for the VIV mitigation of long-span bridges is proposed.Based on the probability of failure,the TMD parameters can be well optimized and control effect can be reasonably evaluated.(3)The damping ratio contributed by multiple viscoelastic TMDs are proposed.Based on this damping ratio,the parameter optimization of multiple viscoelastic TMDs are performed,and the time-domain simulation of the long-span bridge with multiple viscoelastic TMDs under the VIV is performed to validate the optimal viscoelastic TMD.更多还原