共查询到18条相似文献，搜索用时 171 毫秒
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建筑物在强震中可能受到损伤,通过对结构瞬时频率的分析可以诊断出结构的损伤发展过程。本文探讨了基于H ilbert-Huang变换的结构物损伤诊断方法,研究了如何从结构地震响应信号中提取模态响应、1阶模态振型和损伤发展规律。本文采用HHT法分析了Northridge地震中某超高层建筑物的强震记录,分析结果表明:带有间歇检验准则的经验模态分解法能够提取结构的模态振动响应;通过分析不同楼层的相对H ilbert边际谱能够识别出结构的1阶模态振型;分析结构振动中瞬时频率的时变特点,可以直观地掌握振动中结构的损伤发展规律。 相似文献
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《地震工程与工程振动》2021,41(4)
采用过桥车辆振动响应识别桥梁自振特性的间接测量法能够避免传统动载试验测量桥梁振型方法所存在的操作复杂和成本较高等缺点。采用数值模拟的方法,根据车桥耦合振动理论和桥梁振型间接测量法基本原理,对实际工程某连续梁桥建立车辆与桥梁耦合振动的有限元模型,采用双轴半车模型模拟测量车辆,提取车辆匀速通过平整桥面时车辆振动加速度时程响应,并采用带通滤波技术与汉宁窗相结合的处理方法提取分离出与桥梁固有频率相关的桥频分量响应,利用桥频分量响应及其希尔伯特变换构造出与每阶固有频率相对应的振型。采用本方法分析了6种车速、4种社会车辆工况对桥梁振型识别效果的影响特点。数值分析结果表明,车速低于10 km/h以下时高阶振型识别误差较大,车速高于60 km/h以上时振型识别普遍较差,最佳识别车速是30～40 km/h;有社会车辆存在时对桥梁振型识别有利,但是对密集模态识别不利。为推进移动传感间接测量方法在桥梁检测工程中的应用提供理论参考。 相似文献
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模态静力非线性分析中模态选择的研究 总被引：18，自引：4，他引：14
本文应用模态静力非线性分析方法,对多个算例进行了静力非线性分析。比较分析了不同振型组合对计算精度的影响,对模态选择的参数进行了研究,提出采用模态质量参与系数进行模态选择的控制,为模态静力非线性分析方法的推广使用提供参考。另外,分析了结构基本周期对该方法计算精度的影响。 相似文献
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《地震工程与工程振动》2015,(3)
结构振动是多个振型参与的结果。在结构抗震设计及地震工程相关领域,结构模态数值的应用程度越来越高,其准确程度从根本上关系到结构设计和工程抗震的实现效果。为考察阻尼对实际结构模态测试结果的影响,设计了三层剪切型钢框架模型及可调硅油阻尼器。计算其理论模态,并通过三种常用的模态测试方法,对其在阻尼比由小到大逐渐增大的各种工况下的频率和振型进行测试。试验结果表明:阻尼比对结构模态测试结果确有影响,测试精度随着阻尼比的增大而降低,但在实际结构阻尼比量级时,常用测试方法得到的简单结构的模态结果精度可以满足工程计算需要;脉动法、初位移释放法和激振法的测试精度依次提高。 相似文献
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应县木塔环境振动试验 总被引：6，自引：1，他引：5
对于复杂的塔状古建筑物,建立一个合适的简化的数学模型是不易实现的。与强迫振动试验相比,环境振动试验比较简单、方便,所确定出的小振幅水平下的木塔结构动力特性具有足够的精度。本文首先结合应县木塔结构环境振动测试实例对环境振动测试方法作了简要介绍,并采用随机信号数据频域分析方法对测试数据进行了分析,确定木塔结构的自振频率。同时,依据不同测点在固有频率处响应的比及零迟时互相关函数确定木塔结构的振型。最后,本文依据自功率谱和互功率谱采用半功率点法计算各振型的阻尼比。本文分析结果表明,在两水平方向上木塔的振动特性存在些微差异,第一振型阻尼比较第二振型阻尼比大。 相似文献
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本文根据模型试验、原型结构振动测量和理论分析,提出了计算高层剪力墙结构自由振动的实用计算方法。用此法对两幢高层剪力墙房屋进行计算,所得的周期和振型与振动测量结果极为接近。 相似文献
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针对北方某钢管混凝土拱桥东拱肋拱顶合拢高度比设计标高(35.017m)低0.30m,西拱肋拱顶合拢高度比设计标高低0.44m的问题,采用ANSYS软件对其建立空间有限元计算分析模型,并用子空间迭代法对结构进行了模态分析,得到了结构的自振频率和振型.由计算结果可知:该拱桥横向刚度小于纵向刚度,结构横向可能成为薄弱环节;结构的振型多次出现局部振动的特征,表明拱肋和桥面连接较弱.计算结果对该拱桥的检测、维修、改造具有重要价值. 相似文献
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基于环境振动测试的高层钢筋混凝土结构模态参数识别 总被引：2，自引：0，他引：2
根据高层钢筋混凝土结构环境振动测试数据,采用随机信号的频域分析方法,确定了高层结构的自振频率;基于不同测点在固有频率处的响应比及零迟时互相关函数确定了结构的振型;运用自功率谱和互功率谱,采用半功率点法计算了各阶振型的阻尼比.结果表明,环境振动测试能够较好地识别高层结构的1～3阶振型.对实测自振周期与<建筑结构荷载规范>的公式和数值模拟结果进行比较,发现:结构的层数小于20层时,实测值与<规范>规定的值最接近;结构超过20层时,实测值小于<规范>规定的值和数值模拟的结果. 相似文献
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汽轮发电机框架式基础1∶10模型动力分析 总被引：1，自引：0，他引：1
本文依据模态分析理论并结合规范的要求对某火力发电厂 600MW汽轮发电机的框架式基础1∶10模型振动性能进行了研究,采用白噪声随机激振法对该结构进行了空间整体模态分析,从实测数据中获得了动力特性数值。通过与ANSYS有限元软件数值计算结果的对比,表明理论分析模型的可行性。研究结果将为发展汽轮发电机框架式基础的设计原则和优化动力设计方法提供参考。 相似文献
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提出了基于经验模式分解（EMD）的环境激励结构模态参数随机子空间识别（SSI）方法。该方法用设置间断频率的EMD将结构环境振动响应原始信号分解成若干个基本模式分量（IMF）,使每一个基本模式分量仅为结构的某一阶固有模态,进而用随机子空间方法进行模态参数识别。实桥环境振动实验分析结果表明,该方法能有效地避免结构各阶模态之间的相互影响,能够更清晰方便地得到结构的模态参数。 相似文献
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Α new method based on variational mode decomposition (VMD) is proposed to distinguish between coal-rock fracturing and blasting vibration microseismic signals. First, the signals are decomposed to obtain the variational mode components, which are ranked by frequency in descending order. Second, each mode component is extracted to form the eigenvector of the energy of the original signal and calculate the center of gravity coefficient of the energy distribution plane. Finally, the coal-rock fracturing and blasting vibration signals are classified using a decision tree stump. Experimental results suggest that VMD can effectively separate the signal components into coal-rock fracturing and blasting vibration signals based on frequency. The contrast in the energy distribution center coefficient after the dimension reduction of the energy distribution eigenvector accurately identifies the two types of microseismic signals. The method is verified by comparing it to EMD and wavelet packet decomposition. 相似文献
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关于结构振型参与系数和振型贡献的分析 总被引：1，自引：0，他引：1
采用振型分解反应谱法求解多自由度弹性体系的地震反应时,为了在满足所需计算精度的前提下减少工作量,需要对振型数量进行合理的选择,而振型数的确定主要取决于结构各阶振型对总体反应的贡献。通过数学推导,对振型贡献及振型数量的选择问题进行了研究。首先,讨论了振型参与系数的性质,在此基础上给出了能够反映结构振型贡献参数的数学表达式,对这些参数的力学含义进行了解释,并给出了相关证明;其次,对有效质量法、振型位移控制法等基于不同振型贡献标准的确定振型数的方法进行了分析比较,指出了其合理性和不足。本文研究对进一步理解结构振型贡献和振型数的选择问题具有一定的理论意义。 相似文献
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The Fourier p-element method is an improvement to the finite element method, and is particularly suitable for vibration analysis due to the well-behaved Fourier series. In this paper, an iteration procedure is presented for solving the resulting nonlinear eigenvalue problem. Three types of Fourier version shape functions are constructed for analyzing the circular shaft torsional vibration, the plate in-plane vibration and annular plate flexural vibration modes, respectively.The numerical results show that this method can achieve higher accuracy and converge much faster than the FEM based on polynomial interpolation, especially for higher mode analysis. 相似文献
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Sh. Hosseini-Hashemi Mahmoud Karimi D.T. Hossein Rokni 《Soil Dynamics and Earthquake Engineering》2010
Hydroelastic vibration and buckling analysis of horizontal rectangular plates resting on Pasternak foundation and subjected to linearly varying in-plane loads is investigated for different boundary conditions. Fluid is assumed to be inviscid and incompressible. To analyze the interaction of the Mindlin plate with the elastic foundation and fluid system, three displacement components of the plate are expressed in the Ritz method by adopting a set of static Timoshenko beam functions satisfying geometric boundary conditions. Convergence study is first carried out to confirm the stability of the present method. Then, a few comparisons are made for limited cases between present results and the available data in the literature. Finally, parametric study is conducted to highlight the effects of loading factors, fluid levels, foundation stiffness parameters, aspect ratios, thickness to width ratios and different boundary conditions on the critical buckling loads and wet natural frequencies of rectangular plates. 相似文献
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The theoretical and experimental investigation of a cable-stayed bridge after major repair is described in this paper. Strengthening mainly involved the suspension system (originally with prestressed concrete stays) which was retrofitted by means of external tendons. Full-scale tests were conducted to measure the dynamic response of the repaired system; the experimental program included both traffic-induced and free vibration measurements. A total of 16 vertical frequencies and mode shapes were identified in the frequency range of 0–10 Hz. In the theoretical study, vibration modes involving deck, towers and cables were determined by using finite element models which accounted for the strengthening effects. Two- and three-dimensional models were used so that the importance of three-dimensional modes was estimated as well. The experimental results were compared to natural frequencies and mode shapes computed using theoretical models. For most modes the measured and predicted modal parameters compare well, especially for the vertical modes involving in-phase motion of the stays. © 1997 by John Wiley & Sons, Ltd. 相似文献
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Three choices of control variables for meteorological variational analysis (3DVAR or 4DVAR) are associated with horizontal
wind: (1) streamfunction and velocity potential, (2) eastward and northward velocity, and (3) vorticity and divergence. This
study shows theoretical and numerical differences of these variables in practical 3DVAR data assimilation through statistical
analysis and numerical experiments. This paper demonstrates that (a) streamfunction and velocity potential could potentially
introduce analysis errors; (b) A 3DVAR using velocity or vorticity and divergence provides a natural scale dependent influence
radius in addition to the covariance; (c) for a regional analysis, streamfunction and velocity potential are retrieved from
the background velocity field with Neumann boundary condition. Improper boundary conditions could result in further analysis
errors; (d) a variational data assimilation or an inverse problem using derivatives as control variables yields smoother analyses,
for example, a 3DVAR using vorticity and divergence as controls yields smoother wind analyses than those analyses obtained
by a 3DVAR using either velocity or streamfunction/velocity potential as control variables; and (e) statistical errors of
higher order derivatives of variables are more independent, e.g., the statistical correlation between U and V is smaller than the one between streamfunction and velocity potential, and thus the variables in higher derivatives are more
appropriate for a variational system when a cross-correlation between variables is neglected for efficiency or other reasons.
In summary, eastward and northward velocity, or vorticity and divergence are preferable control variables for variational
systems and the former is more attractive because of its numerical efficiency. Numerical experiments are presented using analytic
functions and real atmospheric observations. 相似文献
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某首层柱顶隔震结构动力特性测试研究 总被引：1，自引：0，他引：1
为了达到隔震设计的目的并检验隔震层的工作性能,测试分析了采用首层柱顶隔震技术的某五层框架结构在环境激励和初位移条件下的动力特性,得到了结构的前3阶自振特性如自振频率、振型和阻尼比;分析了初位移条件下隔震层的自由衰减曲线和滞回性能.结果表明:环境激励条件下,隔震结构与非隔震结构动力特性相近,隔震结构在正常使用状态下具有足... 相似文献