可调频调液柱型阻尼器振动控制参数研究

本文介绍了建筑结构利用可调频调液柱型阻尼器减小结构振动的控制系统,由于增设了频率控制装置,增加了ＴＬＣＤ的应用范围,文中阐述了利用ＴＬＣＤ系统减振的基本原理,确定了有关的影响参数并介绍了建筑结构利用ＴＬＣＤ进行振动控制的计算方法。     

利用测试法综合评判打桩振动对建筑物的影响

随着城市建设发展,打桩振动引起的纠纷日渐增多。结合某工程场地打桩振动测试,通过研究场地各方向的衰减规律,综合考虑打桩振动的各影响因素,对实测数据进行分析处理。选择适当的标准评价打桩振动对周边民房影响程度,确定影响范围。     

非线性土木结构振动控制的逆系统方法

采用多变量非线性控制的逆系统理论,将多变量、非线性的复杂被控对象精确线性化成伪线性系统,对于该伪线性系统很容易基于线性系统理论设计综合最优控制器。克服了传统的非线性结构近似线性化控制方法不够精确的缺点,实现了非线性结构的动态精确线性化控制。给出了一个仿真实例,将其控制效果与一般的线性和近似线性化最优控制作了比较,达到同样控制效果时本方法所需控制力显著减小。     

Semiactive control of rigid blocks under earthquake excitation

This paper investigates the usefulness of a semiactive control to reduce the overturning vulnerability of a rigid block on a rigid plane under earthquake excitation. The proposed feedback law is used to set the stiffness of restraints placed at the 2 lower corners of the block. The performance of the semiactive control is numerically validated by subjecting the block to 100 recorded accelerograms. Specific simulations are performed to study the effect of different anchorage design parameters on the utility of the control. Finally, the robustness of the proposed control is addressed with respect to typical issues of the real‐world implementation.     

An explanation of the large PGA value of 2013 Ms7.0 Lushan earthquake at 51BXD station through topographic analysis

In Ms7.0 Lushan earthquake, a large amount of strong ground motion recordings were collected. In this paper, we analyze the recordings carefully. The abnor- mality of ground motion recordings is identified through a log linear regression. In the station of 51BXD, the PGA value has exceeded 1 g, which is the biggest peak ground acceleration （PGA） value obtained from all recordings in this earthquake. The log linear relation shows the PGA value in this station is abnormally large. As this station is located on the footage of a hill, the topographic amplifi- cation factor is explored in order to explain this abnor- mality. Through 3D numerical modeling using spectral element method with transmitting boundary conditions, the amplification factor is quantized. In this station, the topo- graphic amplification is highly polarized in the direction of East-West which agrees with the empirical recordings. This research result suggests us in future directionality of topographic amplification should be considered in the aseismic design.     

Vibration control of cable-stayed bridges—part 1: modeling issues

The objective of the research presented here is to increase the understanding of how the complexities associated with modeling cable-stayed bridges, such as non-linear behaviour and the participation of highly coupled, high-order vibration modes in the overall dynamic response, affect the overall effectiveness of active control schemes. The 316-degree-of-freedom analytical model studied here is based on the Jindo Bridge located in South Korea. Computational considerations associated with control analyses require the size of the model to be significantly reduced, without loss of the important vibration characteristics and complexities. Three separate reduced-order modelling techniques for creating effective control models are studied here: the IRS method, the internal balancing method, and a modal reduction method. These methods are studied and compared on their ability to capture the complex dynamic response of cable-stayed bridges subjected to multiple-support excitation and their ability to create viable and computationally sound state-space models for control analyses. Results show that the modal reduction technique, because of the ability to select only those modes causing the largest force and displacement response, is most effective for control applications. © 1998 John Wiley & Sons, Ltd.     

Efficiency of trenches along railways for trains moving at sub- or supersonic speeds

A full 3D analytical approach is adopted to account for trenches on one or both sides close to a railroad. Low-frequency ground vibrations are investigated due to the passing of trains, and open trenches are used as wave barriers. The modelling technique is based on Fourier transforms and Fourier series. The ground is modelled as a layered semi-infinite domain and the embankment with finite layers. The trenches are obtained by simulating the upper surface layer with two or three finite rectangular regions with appropriate widths. A particular boundary condition is adopted at the vertical sides of all finite regions to enable the solution procedure. Rails and sleepers are accounted for with Euler–Bernoulli beams and an anisotropic Kirchhoff plate with transversal isotropy. The wheel loads from the boogie wheel pairs of the train are simulated as moving forces. Hence, no irregularities in rails or wheels are accounted for.     

地下结构对工程场地地震动场的影响

本文以日本神户市地铁大开站为工程背景,应用大型通用有限元ANSYS软件,分别建立了自然条件下的工程场地土层和建有地下车站结构的土层的二维有限元分析模型。计算了基岩一致地震动输入模式下2个土层模型的动力反应。通过将2个土层模型的动力反应进行比较分析,讨论了地下结构对工程场地地震动场的影响。分析结果表明,日本神户地铁大开站的存在对其邻近区域土层的地震反应有影响,但影响有限。     

连续型隔振屏障在高速铁路环境振动问题治理中的应用研究

为探究高速铁路两侧隔振屏障隔振效果,采用有限元与无限元边界结合的方式进行分析,研究不同连续型隔振屏障及布置形式对隔振效果的影响。通过现场试验与同尺寸、同属性有限元模型对比试验,验证有限元模型合理性。计算结果表明：不同连续型隔振屏障中,空沟隔振效果最优,空沟隔振措施适合高速列车隔振;隔振屏障宽度为0.6～2.5倍波长时,其对隔振效果的影响较小,随着宽度的改变,隔振效果变化幅度较小;隔振屏障深度为3.8～15.2倍波长时,其对隔振效果的影响较明显,随着深度的增加,隔振效果增强;屏障位置对隔振效果的影响较大,建议屏障应靠近路基布置;连续型隔振屏障对高频的隔振效果优于低频。     

大跨度悬索桥环境振动的双向TMD控制

对带有双向ＴＭＤ系统的大跨度悬索桥进行了空间非线性时程响应分析,探讨了ＴＭＤ参数对抑振效果的影响,分析结果显示,ＴＭＤ能够增大结构的表观阻尼,有较大的能量耗散作用,加速振荡的衰减,有效地抑振结构的振动,这表明,用ＴＭＤ技术对大跨度悬索桥的环境振动实施被动控制是一个有效的方法。     

Decentralized robust control of building structures under seismic excitations

Many of the control algorithms proposed for structures subjected to seismic excitations are based on a centralized design philosophy, such as the linear quadratic regulator (LQR) design. The information of all the states of the system is usually required in these methods to determine the control command. For applications involving large‐scale systems, it may be more convenient to design decentralized controllers that depend only on the information of the local states for control command calculation. In this study, a nonlinear decentralized robust control algorithm is proposed. The structural system is decomposed into several artificially uncoupled subsystems. The interconnections between adjacent subsystems are treated as uncertain but bounded disturbances to the subsystems. The controller associated with one subsystem determines the control command based only on the states of the local subsystem. Numerical examples of linear and nonlinear structural models are presented to demonstrate the effectiveness and robustness of the proposed controller. The traditional LQR design is used as a baseline for comparison. Copyright © 2007 John Wiley & Sons, Ltd.     

芦山地震地震动上下盘效应研究

2013年4月20日的芦山7.0级地震是继2008年5月12日汶川8.0级特大地震之后,发生在龙门山断裂带上的又一次大震级逆冲型地震.与汶川地震相比,芦山地震的发震断层没有地表出露,断层的滑动角更大,其逆冲性质更强烈.本文挑选了芦山地震中断层距小于200km的45条强震动记录,基于地震动衰减关系进行统计分析,对比了上盘和下盘台站地震动参数相对于衰减关系的对数残差.结果表明：芦山地震的上下盘效应明显,近断层上盘地震动的高频成分要高于同断层距的下盘;上盘地震动衰减要明显快于下盘.地震动衰减关系用简单的一个距离参数很难描述近场断层尺寸效应的影响,也很难模拟地震动上下盘效应.因此,在近场强地面运动模拟中,应多考虑有限断层模型,以模拟断层的尺寸效应.     

强夯振动衰减规律及其对建筑安全性的影响

依托工程实例,对粉土场地强夯加固振动衰减规律及其对建筑物的影响开展试验研究,探讨了振动加速度与强夯能量、传播距离之间的关系,建立了2种能级夯击振动加速度衰减公式;提出了建筑物最小安全距离的确定方法及减轻强夯振动影响的工程措施。结果表明:强夯振动加速度峰值近似按指数函数衰减,且强夯能量越大,振动衰减速度越快;夯击振动卓越频率为8—10Hz,振源距对振动卓越频率影响不大;振源距达到50m时,2种能级的强夯振动对建筑物影响均可忽略不计。     

非平稳地震激励下隔震曲线梁桥振动控制研究

曲线梁桥由于其平面不规则性导致结构在地震激励下产生弯扭耦合效应,使得隔震曲线梁桥的地震响应更加复杂。目前常用的控制方法是将隔震技术与附加减震装置相结合对曲线梁桥进行控制。本文将地震动考虑为一均匀调制非平稳随机过程,针对隔震曲线梁桥长周期、低频率的特点,选取Clough-Pension平稳地震动功率谱模型作为随机地震动输入模型,对无控(NON-C)、经典线性最优控制(COC)以及序列最优控制算法(SOC)三种状态下的曲线桥梁进行随机响应分析。通过建立曲线梁桥在随机地震动作用下的运动方程,求出减震控制结构的位移谱密度、加速度谱密度响应及时变方差。分析结果表明:序列最优控制算法(SOC)在使隔震层位移得到减小的同时,可以更有效地控制上部结构的地震响应,具有更好的控制效果。     

水平排桩对土体振动抑制作用影响的试验研究

为研究水平放置排桩对土体振动幅值的抑制作用,采用控制变量法进行模型试验,将试验获得的时域信号通过傅里叶变换转换为频域信号,得到频域条件下土体振幅,并绘制土体振幅等值线图,对等值线图不同区域土体振幅进行分析,重点分析振幅显著位置处数值变化。研究结果表明,排桩布置区域上方土体振幅大于排桩布置区域外的土体振幅,沿桩长方向土体振幅大于垂直于桩方向土体振幅;在排桩布置区域上方,排桩对高频波引起的土体振动抑制作用较差,对低频波引起的土体振动抑制作用较明显;排桩埋深越小,对土体振动的抑制作用越明显;排桩布置区域填充率越大,对土体振动的抑制作用越明显;排桩桩径越大,对土体振动的抑制作用越明显。     

区域介质品质因子对地震动参数衰减的影响

本文考虑介质环境表观品质因子,根据美国西部强地震动记录确定了地震动衰减模型中的参数,在不考虑震源机制细节差异的条件下,分析比较了八个地区由于表观品质因子Ｑ值不同导致的地震动加速度傅里叶幅值谱和均方根强度衰减关系的差异。     

高速列车运行引起的地基振动测试与分析

为分析高速列车运行引起的地表处振动峰值加速度随距轨道中心线距离的变化特征,选择8个不同场地类型及路基形式的工程场地进行高速列车运行引起的地表振动加速度测试。研究结果表明,高速列车引起的地表振动加速度随距轨道中心线距离的变化特征因场地条件和路基形式的不同存在显著差异;Ⅱ、Ⅲ、Ⅳ类场地条件下,高速列车引起的地表三分量振动加速度均随距轨道中心线距离的增加而减小,且距轨道近距离处峰值加速度衰减较快,远距离处衰减较慢,Ⅰ类场地条件下,高速列车引起的地表振动加速度随距轨道中心线距离的增加呈先增大后减小的趋势;对于相同路基形式的高速铁路,Ⅲ类场地条件下地表振动峰值加速度随距轨道中心线距离的增加减小速度最快,Ⅱ类场地次之,Ⅳ类场地衰减最慢。     

中国分区地震动衰减关系的确定

本文利用我国丰富地地震工等震线资料,研究了我国烈度衰减关系分区,并建立了分区地震烈度衰减关系。选择既有丰富的强震记录又有烈度衰减关系的美国西部地区作为参考区,并利用本文确定的分区地震烈度衰减关系轩换得到相应的地震动衰减关系式。     

Seismic control of rocking structures via external resonators

Tall rigid blocks are prevalent in ancient historical constructions. Such structures are prone to rocking behaviour under strong ground motion, which is recognizably challenging to predict and mitigate. Our study is motivated by the need to provide innovative nonintrusive solutions to attenuate the rocking response of historical buildings and monuments. In this paper, we examine a novel scheme that employs external resonators buried next to the rocking structure as a means to control its seismic response. The strategy capitalizes on the vibration absorbing potential of the structure-soil-resonator interaction. Furthermore, the benefits of combining the resonators with inerters in order to reduce their gravitational mass without hampering their motion-control capabilities are also explored. Advanced numerical analyses of discrete models under coherent acceleration pulses with rocking bodies of different slenderness ratios under various ground motion intensities highlight the significant vibration absorbing qualities of the external resonating system. The influence of key system parameters such as the mass, stiffness, and damping of the resonator and those of the soil-structure-resonator arrangement are studied. Finally, a case study on the evaluation of the response of rocking structures with external resonators under real pulse-like ground-motion records confirms the important reductions in peak seismic rotational demands obtained with the proposed arrangement.     

Seismic demand based on damage control model—considering basin effect and source effect

The Park and Ang damage model was used as the "Structural Damage Control Model" to study the seismic design parameters. This damage control model included the displacement ductility and hysteretic energy in the analysis of elastic-perfect-plastic single-degree-of-freedom system. Based on this damage control model, the reduction factor and yield base shear coefficient are discussed. Seismic data collected from Taipei basin were used to examine the code-provided yield base shear coefficient which reflects the influence of using a damage control model in the seismic design parameter. Effects of seismic source as well as Taipei basin topography are also considered in examining the variation of yield base shear coefficient.