阻尼器系数对悬挂建筑结构减震效率影响研究

利用拉格朗日方程建立了核筒悬挂建筑结构体系运动方程,采用Longe-Kuta方法求解体系地震动力响应时程。实例计算结果表明,阻尼器系数对悬挂结构的减震效果具有明显影响,楼层位移沿结构高度的分布趋于均匀,且相对于普通无悬挂结构其层间位移、层位移、层速度以及层加速度大幅度减小,而且存在一个优化的阻尼器系数使得结构层间位移有最小值。     

粘弹性阻尼器振动控制仿真分析

为了推进粘弹性阻尼器技术的工程应用,用开尔文模型来描述粘弹性阻尼器的耗能性能,将受控结构的运动微分方程用状态空间法来描述。以MATLAB编制SIMULINK工具箱进行动态仿真,并用ANSYS软件对某钢框架结构有控和无控下进行地震反应时程分析,两算例的计算结果均表明：粘弹性阻尼器有效的控制了结构的地震响应。     

考虑过阻尼模态参与的改进复模态叠加法（英文）

为处理非比例阻尼系统可能出现的过阻尼模态,提出了一种改进的复模态叠加强迫振动分析方法,建议无论模态是否过阻尼,复模态振动分析时应成对使用复模态．以一个连接任意布置外部阻尼器的悬臂梁典型非比例阻尼系统为例,其第1阶模态会随阻尼系数的增加而过阻尼．在厘清复模态响应与实际动力响应关系的基础上阐述了采用改进复模态叠加法获得时域响应、传递函数和方差的完整理论方法．将方程分为实部和虚部,使得原复数域运动方程成为基于实数矩阵的增广状态空间方程,从而克服了采用复数矩阵计算时变响应的困难．此外,针对基于白噪声滤波的外部激励,提出了一种高效方差响应评估方法,降低了计算资源消耗．结果表明,相较于假设模态法,复模态叠加法的结果更接近于有限元结果．基于遍历法研究最优阻尼器参数和位置时,采用多个小阻尼阻尼器优于单个大阻尼阻尼器．     

强震作用下独塔斜拉桥抗震性能分析

以某跨径为110 m的独塔异形斜拉桥为工程背景,通过非线性有限元分析对斜拉桥在强震作用下的地震响应特性及减震措施进行了研究,得出如下结论:相比Lander-amboy波,卓越周期与桥梁固有周期较为接近的Cerro Prieto波能够引起结构较大的地震响应。行波效应能够显著增大工程背景斜拉桥的地震响应,且随着视波速的增大,桥梁的加速度响应明显增大。阻尼系数25 000 kN·s/m为工程背景斜拉桥的最优粘滞阻尼器设计参数,且在塔梁连接处安装该参数粘滞阻尼器后,斜拉桥减震效果显著,尤其能明显减小结构的位移响应。     

具有阻尼结点的半刚性连接框架的地震响应(英文)

通过基于随机振动理论的虚拟激励法,分析了具有非比例阻尼特性、安装有结点阻尼器的半刚性结点框架.用建立在半刚性节点单元的动力分析有限元程序分析半刚性结点框架的地震响应.结果表明,结点阻尼器能有效地减小半刚性结点框架的地震响应.     

多点激励下多跨斜拉桥缩尺模型的地震响应研究．部分2：数值分析

研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。     

运用整体法解决两种类型的连接问题

在力学实际问题中,常常会遇到几个物体连接在一起,在力的作用下运动,求解它们的运动规律及所受外力和相互作用力,这类问题被称为连接体问题．求解这类问题与求解单一物体的力学问题相比较要复杂得多。     

小波分解法在多自由度线性体系地震反应分析中的应用

介绍小波变换的分频机理,利用多分辨分析推导多自由度线性体系地震反应分析的基本公式,建立求解结构动力响应的小波分解法.算例表明:线性体系的地震响应可由各频带动力响应叠加而成,验证了线性系统动力响应唯一性的结论.利用小波多分辨率的特点可安全有效地滤去地震动高频成分,提高信噪比.高频抑制后的重构信号动力响应与原始地震动响应误差很小,说明地震动高频成分对结构振动影响甚微.     

应用人工神经网络（ANN）预测结构的地震响应

提出了基于人工神经网络（ＡｒｔｉｆｉｃｉａｌＮｅｕｒａｌＮｅｔｗｏｒｋｓ）对动力结构进行系统辨识的方法，即应用人工神经网络预测结构地震响应．采用ＢＰ算法的前馈网络（简称ＢＰ网络）对剪切模型结构进行系统辨识．首先用实际地震波及相应的模拟地震响应训练本文提出的ＢＰ网络，然后用“已学会”的ＢＰ网络预测其它地震波激励下的结构地震响应．还讨论了网络拓扑结构、输入单元数等对网络学习和预测的影响．通过本文可以发现，合适的人工神经网络结构能准确地辨识结构动力特性和预测结构动力响应     

考虑阻尼之组合结构的动内力局部效应修正

以往对结构进行动力分析常常忽略局部效应的影响,但实践证明,局放效应在某些结构中占有很大的比重,为得到精确的动力响应,必须考虑局部效应本文在已有的基础上,提出了考虑阻尼之组合结构在地震作用下局部效应的计算方法通过对结构动内力进行局部效应修正前后求解精度的对比,证明了考虑局部效应的重要性．最后,本文对核反应堆堆顶屏蔽给构进行了局部动内力分析,得出了一些有意义的结论。     

高层建筑地震反应的多模态控制(英文)

运用ＭＴＭＤｓ系统对高层建筑的地震反应进行多模态控制研究．首先描述了ＭＴＭＤｓ系统的构造及其主要参数,建立了高层建筑－ＭＴＭＤｓ系统耦联体系的运动方程,并对简谐地面运动激励下的多模态控制进行了参数优化,最后应用ＭＴＭＤｓ系统对受１９４０年Ｅｌ－Ｃｅｎｔｒｏ（ＮＳ方向）地震波激励的某１１层框架建筑进行了数值模拟,其结果显示多模态控制下该框架建筑的顶层位移幅值比单模态控制时降低了２０％左右;从而得出结论：ＭＴＭＤｓ系统是高层建筑地震反应控制的一种有效、可靠并实用的被动控制措施,且多模态控制比单模态控制具有更好的实用性和可靠性,因而展示了更广阔的应用前景．     

Property of critical excitation for moment-resisting frames subjected to horizontal and vertical simultaneous ground motions

It has often been reported that, when building structures are subjected to near-fault earthquake ground motions, horizontal and vertical impulsive inputs may cause critical damage during the first few seconds. In practical design of building structures, however, the safety check, taking into account the effect of multi-component ground motions, is hardly conducted except the design of important structures such as high-rise buildings and nuclear power plants. Ftirthel＇more, it is not clear how the correlation of multi-component ground motions influences the actual safety of structures. In this paper, the detailed property of critical excitation is discussed in association with the relationship between the characteristics of ground motions and those of structures. The properties of various auto power spectral density （PSD） functions of the horizontal and vertical ground motions are investigated, and those of the critical cross PSD function of these two-directional ground motions are found by a devised algorithm in a feasible complex plane. A closed-form expression is derived from the critical relation of the auto PSD functions of the simultaneous inputs. This critical excitation method provides us with a new approach for earthquake-resistant design against the possible future earthquake which causes the critical damages to buildings.     

Seismic response analysis of damper-connected adjacent structures with stochastic parameters

Dynamic response analysis of damper connected adjacent multi-story structures with uncertain parameters is carried out. A formula of the multi degree of freedom （MDOF） for the structure-damper system with stochastic parameters is derived. The uncertainties of mass and stiffness are taken into consideration firstly. The ground acceleration is represented by Kanai-Tajimi filtered non-stationary process. The mean square random responses of structural displacement and story drift are chosen as the optimization objective. The variations of mean square responses of top floor displacements and bottom story drifts in neighboring structures with the damper stiffness and damping coefficient are analyzed in detail. Through the parametric study, the acquiring optimum parameters of damper are regarded as numerical results. Then, a reducing order model of the MDOF system for adjacent structures with mean parameters is presented. The explicit expressions for determining optimal parameters of Kelvin model-defined damper which is used to connect adjacent single degree of freedom （SDOF） structures subjected to a white-noise excitation are employed to achieve the appropriate damper parameters, which are called theory results. Through a comparative study, it can be found that the theory values of damper parameters are consistent with the results based on extensive parametric studies. The analytical results can be obtained by using the first natural frequencies and the total mass of the adjacent deterministic structures with mean parameters. The analytical formulas can be used to find appropriate parameters of damper between adjacent structures for engineering applications. The performance of damper is investigated on the basis of mitigations of mean square random responses of inter-story drifts, displacements and accelerations in adjacent structures. The numerical results demonstrate the robustness of coupled building control strategies.     

Preliminary report of the 2011 off the Pacific coast of Tohoku Earthquake

On March 11, 2011, eastern Japan was shaken by the 2011 off the Pacific coast of Tohoku Earthquake (the Great East Japan Earthquake). Almost 30 000 people have been killed or are missing as a result of that earthquake and the subsequent monster tsunami, as of April 11, 2011. This paper reports several aspects of this devastating earthquake. It has been reported that long-period ground motions, which had been predicted by many researchers, occurred in Tokyo, Nagoya and Osaka. The response characteristics of high-rise buildings to the recorded long-period ground motions are discussed from the viewpoint of resonance and critical excitation. It is shown that high-hardness rubber dampers are very effective in the reduction of vibration duration in addition to the reduction in vibration amplitude.     

汶川地震作用下北川县城建筑物损毁机制研究

在汶川地震作用下,北川县城的建筑物遭到严重损毁.为给北川县及邻近区县防灾规划和工程抗震设防提供科学参考,本次研究在现场实地调查的基础上,对北川县城建筑物损毁机制与县城地质条件之间的关系进行分析,结果表明,北川县城建筑物损毁是由地表破裂、滑坡、崩塌、地表震动等多种破坏机制综合作用的结果.结论:在北川及邻近区县防灾规划中,建筑物的修建应尽量避开断裂展布带、崩滑灾害易发区段等可能对建筑物造成毁灭性破坏的区域,对于已建成区附近的灾害易发点也应采取必要的工程措施加于防治.     

Seismic performance evaluation of steel frame-steel plate shear walls system based on the capacity spectrum method

This paper presents some methods that the standard acceleration design response spectra derived from the present China code for seismic design of buildings are transformed into the seismic demand spectra, and that the base shear force-roof displacement curve of structure is converted to the capacity spectrum of an equivalent single-degree-of-freedom （SDOF） system. The capacity spectrum method （CSM） is programmed by means of MATLABT.0 computer language. A dual lateral force resisting system of 10-story steel frame-steel plate shear walls （SPSW） is designed according to the corresponding China design codes. The base shear force-roof displacement curve of structure subjected to the monotonic increasing lateral inverse triangular load is obtained by applying the equivalent strip model to stimulate SPSW and by using the finite element analysis software SAP2000 to make Pushover analysis. The seismic performance of this dual system subjected to three different conditions, i.e. the 8-intensity frequently occurred earthquake, fortification earthquake and seldom occurred earthquake, is evaluated by CSM program. The excessive safety of steel frame-SPSW system designed according to the present China design codes is pointed out and a new design method is suggested.     

Use of probabilistic and deterministic measures to identify unfavorable earthquake records

This study introduces measures to identify resonant （concentration of energy in a single or a few frequencies） or unfavorable earthquake ground motions. Probabilistic measures based on the entropy rate and the geometric properties of the power spectral density function （PSDF） of the ground acceleration are developed first. Subsequently, deterministic measures for the frequency content of the ground acceleration are also developed. These measures are then used for identifying resonance and criticality in stochastic earthquake models and 110 acceleration records measured at rock, stiff, medium and soft soil sites. The unfavorable earthquake record for a given structure is defined as the record having a narrow frequency content and dominant frequency close to the structure fundamental natural frequency. Accordingly, the measures developed in this study may provide a basis for selecting records that are capable of producing the highest structural response. Numerical verifications are provided on damage caused to structures by identified resonant records.     

基础隔震结构的设计与分析

探讨分析了结构基础隔震应用中应注意的问题,提出了非线性动力时程分析计算模型并编制了程序。借助该程序,分析了基础隔震结构在地震作用下的层间位移、加速度和剪力等地震反应,并与相同结构未隔震的建筑的地震反应进行了对比。     

东日本大地震对避难所规划和建设的启示

东日本大地震给日本和全世界带来了巨大灾难。一方面从震后灾民避难生活暴露出的城镇避难所规划与建设的隐患和不足中汲取教训,另一方面日本救灾体制健全,建筑物抗震性能高,国民防灾意识强．大量建设避难场所,重视防震减灾及相关学科的科研工作等,都为我国地震避难所的规划和建设提供了一些有益的启示。