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1.
随机结构动力分析的扩阶系统方法   总被引:5,自引:0,他引:5  
李杰 《工程力学》1996,13(1):93-102
本文发展了一类用于随机结构系统动力分析的扩阶系统方法。基于随机空间的正交展开理论,文中推导给出了扩阶系统动力方程的一般公式。这组公式可以适用于同时具有随机质量、随机阻尼、随机刚度参数的多自由度动力系统。通过引入虚拟结构的概念,文中建议了形成扩阶系统动力矩阵的有限元方法。通过对比算例分析,证实了扩阶系统方法的可行性与可靠性。最后,讨论了一个很重要现象:随机系统均值反应与相应均值参数系统反应之间的差异并指出了此差异的意义。  相似文献   

2.
随机结构系统建模问题研究   总被引:2,自引:0,他引:2  
初步研究了随机结构系统的建模问题。本文首先给出了随机结构系统建模的一般定义。然后,以随机结构分析的扩阶系统方法为基础,建议了一类二阶段迭代的随机建模方法。最后,通过仿真算例,说明了二阶段建模方法的实用性。  相似文献   

3.
基于函数的正交分解、次序正交分解与区间数学理论,推导出区间扩阶系统方程,并利用不确定性结构分析的扩阶系统方程对具有不确定性参数的结构系统进行静力分析。将不确定参数处理为有界区间数,基于有限元模型和区间结构力学矩阵的线性分解形式,通过区间扩阶系统方程和有约束的非线性优化方法,对具有区间参数的结构静力响应进行计算。通过数值算例,对区间扩阶系统方法的结果与解析结果进行对比,分析了区间扩阶系统的展开阶数和不确定度对计算结果的影响,数值结果表明了区间扩阶系统方法的可行性与有效性。  相似文献   

4.
解随机结构扩阶系统动力方程一直是随机结构响应求解中的难点。借助Gegenbauer多项式逼近法,将随机参数系统动力响应计算问题转化为与其等价的确定扩阶系统的响应计算问题。用精细积分对过滤白噪声的非平稳随机激励进行K_L分解,利用K_L向量的能量集中的特点,用少量的K_L向量参与扩阶系统的响应计算即可获得较精确的响应值,...  相似文献   

5.
以含有界随机参数结构模型为控制模型,研究了不确定结构的鲁棒H_∞控制问题。在控制系统设计过程中,通过Gegenbauer多项式将不确定结构控制模型中随机参数引入到结构的确定性扩阶系统之中;再基于该扩阶系统,结合有界实引理,采用线性矩阵不等式(linear matrix inequality,LMI)推导得到控制系统的增益矩阵,使得闭环系统传递函数对不确定性扰动满足H_∞干扰抑制。最后通过一结构算例,结合自定义的鲁棒性能评价指标,分析比较了基于不同控制模型设计的控制系统鲁棒性能的差异。仿真分析结果表明,模型参数和环境激励的不确定性对控制系统控制效果有较大影响,所述控制系统设计方法相较其他两类方法具有更好的鲁棒性。  相似文献   

6.
弹性-粘弹性复合结构系统的随机响应分析   总被引:1,自引:0,他引:1  
张天舒  方同 《工程力学》2001,18(5):71-76,114
本文建立在随机振动时域复模态分析的基础上,利用扩阶状态变量,将弹性-粘弹性复合结构系统的微分积分动力学方程变换成常规的状态方程,提出了一种分析弹性-粘弹性复合结构系统随机响应的方法,得到了弹性-粘弹性复合结构系统在平稳随机激励下响应相关函数矩阵的表达式,并对典型的平稳随机激励(平稳白噪声激励及平稳滤过白噪声激励)情形,进行了分析,得到了典型平稳随机激励下,弹性-粘弹性复合结构系统响应相关函数矩阵的复代数解析表达式。所提分析方法简便、易用,无论单自由度系统或多自由度系统均可适用。本文方法为粘弹性系统的随机响应分析提供了一条途径。  相似文献   

7.
对单自由度广义Maxwell和多自由度Maxwell阻尼耗能结构非平稳随机地震响应问题进行了系统研究。首先通过构建单自由度和多自由度耗能结构在原始空间和扩阶空间上的特征值和特征向量的精确对应关系,将耗能结构位移、速度和阻尼器受力的时域响应计算公式用结构原始空间上的特征值和特征向量解析表出;然后针对7种经典均匀调制白噪声地震激励和2种经典均匀调制滤过白噪声地震激励,获得了耗能结构位移、速度和阻尼器受力的非平稳均方响应的解析解,并使耗能结构非平稳响应的解析分析与计算,完全转化为耗能结构在原始空间的特征值和特征向量的解析分析与计算,从而构建了基于耗能结构非扩阶特征值和特征向量分析,获得耗能结构非平稳地震响应解析解的一整套方法。  相似文献   

8.
张天舒  方同 《工程力学》2001,18(5):71-76,114
本文建立在随机振动时域复模态分析的基础上,利用扩阶状态变量,将弹性-粘弹性复合结构系统的微分积分动力学方程变换成常规的状态方程,提出了一种分析弹性-粘弹性复合结构系统随机响应的方法,得到了弹性-粘弹性复合结构系统在平稳随机激励下响应相关函数矩阵的表达式,并对典型的平稳随机激励(平稳白噪声激励及平稳滤过白噪声激励)情形,进行了分析,得到了典型平稳随机激励下,弹性-粘弹性复合结构系统响应相关函数矩阵的代数解析表达式。所提分析方法简便、易用,无论单自由度系统或多自由系统均可适用。本文方法为粘弹性系统的随机响应分析提供了一条途径。  相似文献   

9.
为建立设置支撑的实用黏弹性阻尼器耗能结构及阻尼器系统的抗震动力可靠度分析方法,提出了在非扩阶空间上,基于非均匀和完全非平稳地震激励下,设置支撑的实用黏弹性阻尼器耗能隔震系统响应的通用解析解。对于设置支撑的实用黏弹性阻尼器做等效变换,并建立隔震结构系统的运动方程,在非扩阶空间上获得系统在任意激励和非零初始条件下瞬态响应的非正交模态叠加精确解。基于地震动的强度非平稳和频率非平稳,获得了耗能隔震结构位移、速度,阻尼器受力、受力速度,支撑位移、速度以及阻尼器位移、速度的非平稳均方响应通用解析表达式,并具体得到经典均匀与非均匀调制非平稳随机地震激励和C-P完全非平稳地震动功率谱模型的具体响应解析解。通过结构系统各响应基于该方法的频响函数与直接求解的频响函数对比验证了该方法的正确性。该分析方法的建立为设置支撑的实用黏弹性阻尼器耗能结构及阻尼器系统的抗震动力可靠度分析乃至抗震设计方法的研究提供了一套新的分析途径。  相似文献   

10.
对多自由度基础隔震结构基于Clough-Penzien谱随机地震响应问题进行了系统研究。首先建立了运动方程,然后用第一振型将上部结构展开,针对所得方程为非经典阻尼、非对称质量和非对称刚度情况,用复模态法和扩阶法解耦,获得了以第一振型表示的结构随机地震响应的解析解,对单自由度隔震体系,此解即为结构响应的精确解,从而建立了两自由度体系在任意非经典阻尼、非对称质量和非对称刚度情况下基于Clough—Penzien谱随机地震响应解析解分析的一般方法。该方法也可用于带TMD、TLD结构、无损伤“加层减震”加固结构的随机地震响应分析及其基于动力可靠性约束的优化设计。  相似文献   

11.
System identification and reliability evaluation play a significant role in structural health monitoring to ensure the serviceability and safety of existing structures. Although the development of system identification methods has attained much attention and some degree of maturity, reliability evaluation of existing structures still remains a challenging problem especially when uncertainties in measurement data and inherent randomness, which are inevitably involved in civil structures, are considered. In this regard, this paper presents a framework for integrated system identification and reliability evaluation of stochastic building structures. Two algorithms are proposed to respectively evaluate component reliability and system reliability of stochastic building structures by combining a statistical moment-based system identification method and a probability density evolution equation-based reliability evaluation method. System identification is embedded in the procedure of reliability evaluation of a stochastic building structure. The uncertainties in both the structure and the external excitation are considered. Numerical examples show that the structural component and system reliabilities of a three-story shear building structure with three damage scenarios can be effectively evaluated by the proposed methods.  相似文献   

12.
System identification and reliability evaluation play a significant role in structural health monitoring to ensure the serviceability and safety of existing structures. Although the development of system identification methods has attained much attention and some degree of maturity, reliability evaluation of existing structures still remains a challenging problem especially when uncertainties in measurement data and inherent randomness, which are inevitably involved in civil structures, are considered. In this regard, this paper presents a framework for integrated system identification and reliability evaluation of stochastic building structures. Two algorithms are proposed to respectively evaluate component reliability and system reliability of stochastic building structures by combining a statistical moment-based system identification method and a probability density evolution equation-based reliability evaluation method. System identification is embedded in the procedure of reliability evaluation of a stochastic building structure. The uncertainties in both the structure and the external excitation are considered. Numerical examples show that the structural component and system reliabilities of a three-story shear building structure with three damage scenarios can be effectively evaluated by the proposed methods.  相似文献   

13.
The sensitivity of the stochastic response of linear behaving structures controlled by the novel Vibrating Barrier (ViBa) device is scrutinized. The Vibrating Barrier (ViBa) is a massive structure, hosted in the soil, calibrated for protecting structures by exploiting the structure–soil–structure interaction effect. Therefore the paper addresses the study of the sensitivity of soil–structure coupled systems in which the soil is modelled as a linear elastic medium with hysteretic damping. In order to accomplish efficient sensitivity analyses, a reduced model is determined by means of the Craig–Bampton procedure. Moreover, a lumped parameter model is used for converting the hysteretic damping soil model rigorously valid in the frequency domain to the approximately equivalent viscous damping model in order to perform conventional time-history analysis. The sensitivity is evaluated by determining a semi-analytical method based on the dynamic modification approach for the case of multi-variate stochastic input process. The ground motion is modelled as non-stationary zero-mean Gaussian random process defined by a given evolutionary Power Spectral Density function. The paper presents the sensitivity of the response statistics of a model of an industrial building, passively controlled by the ViBa, to relevant design parameters. Comparisons with pertinent Monte Carlo Simulation will show the effectiveness of the proposed approach.  相似文献   

14.
We present a probabilistic analysis of a structure with uncertain parameters subject to arbitrary stochastic excitations in a frequency domain. The problem of stochastic dynamic analysis of a linear system in a frequency domain is formulated by taking into consideration the uncertainty of structural parameters. The solution is based on the idea of a random frequency response vector for stationary input excitation and a transient random frequency response vector for nonstationary one which are used in the context of spectral analysis in order to determine the influence of structural uncertainty on the random response of structure. The numerical spectral analysis of the building structure under wind and earthquake excitation is provided to demonstrate the described algorithms in the context of computer implementation.  相似文献   

15.
本文探讨受斜拉弹簧阻尼器模型装置(CTSD)控制的高层建筑结构在顺风向脉动风激励下的随机风振反应问题.文中将高层建筑和CTSD控制机构作为一个整体的耦合体系.同时考虑体系阻尼的非正交性,建立了一种以复模态组合为基础的新的随机反应分析方法——复模态状态空间法;导得了受控体系状态反应以及结构各层反应统计解的统一表达式.通过对框架型高层建筑的实例计算以及与非耦合实振型反应结果的比较表明,该方法是很有理论和实用价值的.  相似文献   

16.
项梦洁  陈隽 《工程力学》2021,38(8):85-96
城市建筑群的动力可靠度评估对于区域防灾减灾具有重要意义。场地效应会导致地震动的空间变异性和土-结构相互作用效应,进而显著影响区域建筑群的非线性地震响应,而确定性区域震害模拟方法仍不足以准确反映随机建筑群动力系统的整体性态。该研究引入实测地震动场和土-结构相互作用效应,发展了建筑群系统非线性地震响应时域求解方法,并遵循概率守恒假定,建立基于概率密度演化方法(PDEM)的建筑群系统动力可靠度评估框架。以某高层框架结构建筑群为例,进行了场地效应下确定性建筑群非线性地震响应分析,进而完成了随机建筑群动力可靠度评估,并评估了场地效应对建筑群系统动力可靠度影响,得到了有益结论。  相似文献   

17.
 用摄动随机无网格伽辽金法(PSEFGM)求解随机结构的响应,然后采用蚂蚁算法对结构可靠性进行了分析。摄动随机无网格伽辽金法具有不需要划分单元和精度高等特点。蚂蚁算法是一种智能型随机搜素优化算法,对目标函数没有任何可微甚至连续的要求,可有效克服经典算法易于陷入局部最优解的常见弊病。数值实例表明,在随机结构可靠性分析方面,随机无网格迦辽金法与蚂蚁算法比经典算法具有明显的优势。  相似文献   

18.
This paper presents the stochastic elastic modulus reduction method for system reliability analysis of spatial variance frames based on the perturbation stochastic finite element method (PSFEM) and the local average of a random field. The stochastic responses and reliability index of each element of a structural frame are characterized by the PSFEM and the first-order second-moment method, to properly handle the correlation structures and scale of fluctuation of random fields. A strategy of elastic modulus adjustment for the estimation of system reliability is developed to determine the range and magnitude of elastic modulus reduction, by taking the element reliability index as a governing parameter. The collapse mechanism and system reliability index of a stochastic framed structure are determined through iterative computations of the PSFEM. Compared with the failure mode approaches in traditional system reliability analysis, the proposed method avoids two major difficulties, namely the identification of significant failure modes and estimation of the joint probability of failure modes. The influences of the correlation structure and scale of fluctuation of the random field upon system reliability are investigated to demonstrate the accuracy and computational efficiency of the proposed methodology in system reliability analysis of spatial variance frames.  相似文献   

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