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1.
采用小波变换将地震加速度记录分解为若干小波分量,通过两榀钢筋混凝土框架在这些小波分量及其不同组合作用下的非线性动力分析,找出对框架非线性响应影响最大的小波分量。结果表明,控制框架非线性响应的小波分量为最靠近框架基本周期的低频小波分量,在为结构非线性响应分析遴选地震动记录时应注意这种特点。 相似文献
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基于运营环境和提升小波变换的桥梁损伤检测研究 总被引：1，自引：0，他引：1
根据损伤桥梁在车辆荷载作用下的动力响应特点,以及提升小波变换对信号突变信息的放大功能,提出了利用桥梁运营荷载作用下加速度响应提升小波变换系数的分布特性对结构损伤进行识别的方法。首先,采集桥梁在行车荷载作用下的加速度响应信号;然后,对加速度响应信号进行提升小波变换,分别利用加速度响应信号、加速度响应信号差,提升小波变换系数空间变化的峰值识别损伤位置;最后,对行车速度、损伤位置、损伤程度和测量噪声对损伤识别效果的影响进行了分析讨论。结果表明：在行车速度8m/s以下、测量噪声不高于5%情况下,利用运营荷载作用下桥梁单点动力响应信号提升小波变换,可以实现桥梁多处损伤的检测和识别。 相似文献
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在一定程度上,桩长是影响桩-土-结构体系动力分析复杂程度的关键因素之一,在桩-土-结构相互作用的数值模拟中对桩长进行适当简化可以提高计算效率,尤其对具有大量长桩基础的结构体系。基于Boulanger模型和OpenSees软件,分析了软粘土地基-单桩结构体系地震反应中桩身的位移、弯矩、剪力的分布特点以及桩顶上部结构的加速度响应,探讨了结构体系振型及振型周期随桩长的变化特点,进一步提出了等效计算桩长的桩-土-结构模型。研究表明,当结构体系前3阶的振型周期的变化率控制到2.5%时,对应的等效计算桩长分析模型能实现较高的动力响应计算精度,其动力响应误差已降低至5%以内;等效计算桩长可以通过动力响应误差控制精度要求确定,对于软粘土地基中的单桩基础结构,建议将前3阶振型周期的变化率控制到2.5%时的计算桩长作为等效计算桩长。 相似文献
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结构动力灵敏度分析中的几个问题 总被引：3，自引：0，他引：3
结构动力灵敏度分析是进行抗震结构优化设计和考虑参数不确定性进行动力可靠性分析的基本步骤。本文就结构动力分析中几个常用的计算过程进行灵敏度分析研究,给出了Choleskey分解矩阵及其它常用数学变换的灵敏度计算表达,分析了振型灵敏度的传递作用,指出对于一般的剪切型结构可以不考虑振型及振型参与系数的灵敏度,从而使问题大为简化。本文还讨论了结构动力反应与各基本参数的灵敏度之间的关系,提出了直接通过结构地震反应得到灵敏度谱的设想。作者认为,通过大量的统计分析可以得到工程上实用的地震反应灵敏度谱。 相似文献
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利用小波变换时-频局部化性能,提出了基于小波能量分布向量的结构损伤识别方法。首先建立无损结构响应信号小波能量分布的总体向量;其次,将实测动力响应信号分解为小波包组分,计算其小波能量分布向量(样本向量);通过样本向量和总体向量之间的马氏距离识别损伤。该方法仅利用单测点结构响应数据进行损伤识别,实验方便,计算简单,并通过钢梁试验对损伤识别方法进行了试验验证,识别结果表明小波能量分布向量是一个比较好的结构损伤指标。 相似文献
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利用小波多分辨率分析将地震动加速度分解为多频段小波分量,并运用复模态方法推导其计算层间隔震体系在地震作用下的动力响应公式,讨论各频段地震信号及结构响应的能量分配。同时利用小波时频工具分析地震动能量在时频域内的分布对层间隔震结构响应的影响,进而为考察地震动非平稳性对层间隔震结构非线性分析的影响提供方法。利用小波分析的以上优势,对一典型层间隔震结构分别进行弹性和弹塑性分析,结果表明弹性体系在地震作用下的响应可由该地震波各小波分量的响应叠加而得,地震动能量在时间上的集中会对层间隔震结构响应产生不利影响。 相似文献
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一种基于位移的改进静力弹塑性分析方法 总被引：6，自引：0，他引：6
静力弹塑性分析作为一种新的结构抗震性能评估方法，近些年得到很大的推广。本文在已有的研究基础上，通过一种基于位移控制的多阶振型组合的静力推覆分析，采用自适应的水平加载方式，考虑高阶振型的影响。对一中等高度的结构进行推覆分析，结果表明，与采用不变的水平菏载分布形式的一般静力推覆分析比较，基于本文Pushover分析所得的结构响应与非线性动力时程分析所得结构的响应更为近似，尤其在受结构高阶振型影响较明显的结构层间位移角及层间剪力方面，其结果同动力时程分析所得更为接近。 相似文献
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近些年来提出的数值方法虽克服了应用复阻尼模型求解动力响应时可能出现的发散现象,但其计算过程繁杂且不能表达出结构动力特性及响应随结构参数的变化规律。论文参照三对角Toeplitz矩阵特征值问题的数学解法,推导出水平剪切型结构各阶自振频率、振型函数的解析形式。通过对运动方程进行Fourier变换,得到复阻尼理论下结构的传递函数解析式,直观地表达出结构动力特性及响应随结构参数的变化规律。最后通过算例对比分析,结果表明:提出的复阻尼模型的解析计算方法克服了时域发散问题,并与时域数值计算方法的位移响应时程对比发现,两种方法得到的时程曲线吻合程度较高,位移峰值也基本一致。同时,对比两种方法在底层刚度变化时的动力响应,解析方法的计算曲线更光滑,避免了数值方法的离散误差问题。 相似文献
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本文采用子空间迭代法分析了单层膜型网壳结构的自振特性;推导了大跨空间结构几何非线性地震响应时程分析的计算过程,编制相应的计算程序,用振型分解反应谱法与时程法进行了结构地震响应特性分析。研究表明:膜型网壳结构的抗震性能比较好;用反应谱法分析时,水平地震作用下截断振型取15、竖向地震作用下取60可满足工程设计要求;用反应谱法计算结构竖向地震响应是安全可靠的,但进行水平地震响应分析时,最终还需用时程法进行验算。 相似文献
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Nonlinear lateral interaction in pile dynamics 总被引：4，自引：0，他引：4
A model for pile lateral response to transient dynamic loading and to harmonic loading is presented allowing for nonlinear soil behaviour, discontinuity conditions at the pile-soil interface and energy dissipation through different types of damping. The approach is used to establish equivalent linear stiffness and damping parameters of single piles as well as dynamic interaction factors for approximate nonlinear analysis of pile groups. The applicability of these parameters to the pile-group analysis was examined, and a reasonable agreement with the direct analysis was found. The superposition technique may be used to analyze the response of small pile groups. Also, the dynamic stiffness of pile groups is greatly affected by both the nonlinear behavior of the soil and the slippage and gapping between the pile and soil. For a basic range of soil and pile parameters, equivalent linear stiffness and damping parameters of single piles and interaction factors for approximate nonlinear analysis are provided. 相似文献
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Gaussian mixture–based equivalent linearization method (GM-ELM) is a recently developed stochastic dynamic analysis approach which approximates the random response of a nonlinear structure by collective responses of equivalent linear oscillators. The Gaussian mixture model is employed to achieve an equivalence in terms of the probability density function (PDF) through the superposition of the response PDFs of the equivalent linear system. This new concept of linearization helps achieve a high level of estimation accuracy for nonlinear responses, but has revealed some limitations: (1) dependency of the equivalent linear systems on ground motion intensity and (2) requirements for stationary condition. To overcome these technical challenges and promote applications of GM-ELM to earthquake engineering practice, an efficient GM-ELM-based fragility analysis method is proposed for nonstationary excitations. To this end, this paper develops the concept of universal equivalent linear system that can estimate the stochastic responses for a range of seismic intensities through an intensity-augmented version of GM-ELM. Moreover, the GM-ELM framework is extended to identify equivalent linear oscillators that could capture the temporal average behavior of nonstationary responses. The proposed extensions generalize expressions and philosophies of the existing response combination formulations of GM-ELM to facilitate efficient fragility analysis for nonstationary excitations. The proposed methods are demonstrated by numerical examples using realistic ground motions, including design code–conforming nonstationary ground motions. 相似文献
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The energy transmitting boundary used in programs such as FLUSH and ALUSH is a very accurate and useful technique for the earthquake response analysis of soil–structure interaction systems. However, it is applicable only to linear analyses or equivalent linear analyses, because it can be calculated only in the frequency domain. The author has proposed methods for transforming frequency-dependent impedance into the time domain. In this paper, an earthquake response analysis method for a soil–structure interaction system, using the energy transmitting boundary in the time domain, is proposed. First, the transform of the transmitting boundary matrices to the time domain using the methods proposed by the author is studied. Then, linear and nonlinear time history earthquake response analyses using the boundary are performed. Through these studies, the validity and efficiency of the proposed methods are confirmed. 相似文献
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A lumped parameter model for time‐domain inertial soil‐structure interaction analysis of structures on pile foundations 
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下载免费PDF全文 The paper presents a lumped parameter model for the approximation of the frequency‐dependent dynamic stiffness of pile group foundations. The model can be implemented in commercial software to perform linear or nonlinear dynamic analyses of structures founded on piles taking into account the frequency‐dependent coupled roto‐translational, vertical, and torsional behaviour of the soil‐foundation system. Closed‐form formulas for estimating parameters of the model are proposed with reference to pile groups embedded in homogeneous soil deposits. These are calibrated with a nonlinear least square procedure, based on data provided by an extensive non‐dimensional parametric analysis performed with a model previously developed by the authors. Pile groups with square layout and different number of piles embedded in soft and stiff soils are considered. Formulas are overall well capable to reproduce parameters of the proposed lumped system that can be straightforwardly incorporated into inertial structural analyses to account for the dynamic behaviour of the soil‐foundation system. Some applications on typical bridge piers are finally presented to show examples of practical use of the proposed model. Results demonstrate the capability of the proposed lumped system as well as the formulas efficiency in approximating impedances of pile groups and the relevant effect on the response of the superstructure. 相似文献
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This study investigates the effect of nonlinear inertia on the dynamic response of an asymmetric building equipped with Tuned Mass Dampers (TMDs). In the field of structural engineering, many researchers have developed models to study the behavior of nonlinear TMDs, but the effect of nonlinear inertia has not received as much attention for asymmetric buildings. To consider nonlinear inertia, the equations of motion are derived in a local rotary coordinates system. The displacements and rotations of the modeled building and TMDs are defined by five-degree-of-freedom (5-DOFs). The equations of motion are derived by using the Lagrangian method. Also in the proposed nonlinear model, the equations of motion are different from a conventional linear model. In order to compare the response of the proposed nonlinear model and a conventional linear model, numerical examples are presented and the response of the modeled buildings are derived under harmonic and earthquake excitations. It is shown that if the nonlinear inertia is considered, the response of the modeled structures changes and the conventional linear approach cannot adequately model the dynamic behavior of the asymmetric buildings which are equipped with TMDs. 相似文献
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A modified force analogy method (MFAM) is developed to simulate the nonlinear inelastic response of reinforced concrete (RC) structures. Beam–column elements with three different plastic mechanisms are utilized to simulate inelastic response caused by moment and shear force. A multi‐linear hysteretic model is implemented to simulate the nonlinear inelastic response of RC member. The P‐Δ effect of the structure is also addressed in MFAM. Static and dynamic inelastic response of structure, damage condition and failure type for structural element, structural limit state and collapse time can also be simulated using MFAM. Compared with the general algorithm, the MFAM provides less computational time especially in the case of large structural system. It is also easier to be written as computer program. Three test data groups, which include cyclic loading test data of a non‐ductile RC bridge column, a two‐storey RC frame, and dynamic collapse test data of a non‐ductile RC portal frame, are selected to confirm the effectiveness of applying MFAM to simulate the inelastic behaviour of structures. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
18.
Jun Iyama 《地震工程与结构动力学》2005,34(15):1799-1815
The response of an elasto‐plastic single degree of freedom (SDOF) system to ground motion is estimated based on wavelet coefficients calculated by discrete wavelet transform. Wavelet coefficients represent both the time and frequency characteristics of input ground motion, and thus can be considered to be directly related to the dynamic response of a non‐linear system. This relationship between the energy input into an elastic SDOF system and wavelet coefficients is derived based on the assumption that wavelets deliver energy to the structure instantaneously and the quantity of energy is constant regardless of yielding. These assumptions are shown to be valid when the natural period of the system is in the predominant period range of the wavelet, the most common scenario for real structures, through dynamic response analysis of a single wavelet. The wavelet‐based estimation of elastic and plastic energy transferred by earthquake ground motion is thus shown to be in good agreement with the dynamic response analysis when the natural period is in the predominant range of the input. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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Hilbert-Huang Transform(HHT)是一种新的适用于非线性、非平稳信号,且具有自适应性的数据处理方法．本文简要介绍了一座45层钢筋混凝土框架结构及其振动台试验模型概况. 利用HHT分析了模型结构在不同烈度地震中的反应记录,得到了Hilbert时频幅值三维分布和Hilbert边际谱．Hilbert谱得到记录能量集中分布的频段与时间范围,捕捉到信号变化的主要特征. Hilbert边际谱曲线形状和峰值频率值随着地震烈度的升级而发生了相应变化,而且所有的结果图形体现出相同的规律性,预示着Hilbert边际谱在土木工程结构安全评价中的应用前景． 相似文献
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A general step-by-step solution technique is presented for the evaluation of the dynamic response of structural systems with physical and geometrical nonlinearities. The algorithm is stable for all time increments and in the analysis of linear systems introduces a predictable amount of error for a specified time step. Guidelines are given for the selection of the time step size for different types of dynamic loadings. The method can be applied to the static and dynamic analysis of both discrete structural systems and continuous solids idealized as an assemblage of finite elements. Results of several nonlinear analyses are presented and compared with results obtained by other methods and from experiments. 相似文献