单自由度体系地震动输入功率谱的确定

将几种地震动功率谱输入模型换算成和目标反应谱相对应的地震动输入,并应用于单自由度体系分析.结果表明,使用孙景江/江近仁迭代法将目标反应谱换算得到的等价功率谱输入精度较高,建议可以在功率谱分析方法中使用.     

新型单自由度基础隔震体系简化计算方法研究

本文建立了一种新型的单自由度体系基础隔震结构实用设计方法，该方法考虑了上部结构的变形、简便，合理，可靠，与传统抗震设计方法概念比较接近，便于在工程应用中推广。     

多点输入随机地震动拱坝-地基体系反应分析

采用等效地基集总参数方法,推导了拱坝－地基体系的简化多点随机输入分析模型,对拱坝－地基动力相互作用体系在多点随机输入地震波作用下的随机响应到进行了分析,并对地基柔度及地震动空间相干性损失对拱坝随机响应的影响进行了讨论。     

Random response analysis of a non-linear soil-suspension bridge pier

The structure analysed herein is a tower and pier system of a long-span suspension bridge. The tower shaft is modelled to allow classical normal modes decomposition in order to reduce higher modes. The pier is assumed to be rigid body free to translation as well as to rocking motion, being reacted by the surrounding soil compliance that is derived from a continuum mechanics approach. Linear and non-linear soil and structural dynamic interaction is dealt with by random vibration theory with use of the linearization technique and complex modal analysis. Primary interest is placed on the investigation of the dynamic characteristics of the total interaction system and the rms response with change of the soil condition and input excitation level. Also discussed is the approximate response analysis, using classical normal modes for the interaction system, for purposes of practical design.     

刚性结构基础隔震随机地震响应及优化分析

运用随机振动的时域复模态分析方法，对刚性结构房屋基础隔震体系在平稳随机地震激励下的响应进行了分析，得出隔震结构体系的地震反应统计特征。在此基础上，结合基础隔震结构均方响应和地震激励均方值之比与频率比、阻尼比的关系曲线以及基于失效概率下位移限值与频率比、阻尼比的关系曲线，提出采用图解法确定隔震装置合理优化的参数取值。     

结构-地基体系的非比例阻尼影响及随机地震响应分析

针对结构-地基体系随机地震响应分析中存在的非比例阻尼耦合问题，采用不同非比例阻尼判断准则研究了结构-地基体系在不同刚度比，不同阻尼比下结构与地基间的阻尼耦合及体系不同振型间的阻尼耦合问题，推导了用于结构-地基非比例阻尼系统随机分析的小参数随机摄动分析公式，并用于地下大型有衬砌洞室的随机地震响应分析中。     

成层地基一维土层对地震的随机反应分析

首先基于改进的一维剪切梁模型，对成层土层推导了确定自振频率、振型函数、参与系数及稳态动力响应的封闭型解析表达式，首次证明了成层土层振型函数的正交性，然后在此基础上，利用随机振动理论，研究了成层土层对地震的随机动力反应问题，关于基岩输入地震加速度的功率谱密度函数，考虑了两种形式：白噪声谱和过滤白噪声谱。数值计算结果表明：对这两种谱，土层的最大期望反应是不相同的；平稳输入与输出过高估计了土层的随机反应。     

大跨度结构TMD减震系统多点激励的地震随机响应分析

众多研究表明，对大跨度结构进行抗震分析时，必须采用非一致地震激励模型。本文对带TMD系统的大跨度结构考虑地震行波效应后的随机地震响应问题进行了研究。文中建立了结构的动力方程，并利用虚拟激励法求解。研究结果表明，对于大跨度结构装设TMD子结构以后可显著地降低结构的位移、速度和加速度响应，但在设计TMD减震系统时，必须考虑到地震激励的非一致性，否则可能会使预期的减震效果失效。     

Optimization of the stochastic response of a bridge isolation system with hysteretic dampers

A bridge structure with a seismic isolation system consisting of rubber bearings and hysteretic dissipators is considered. The non-linear equations of motion are derived for the first mode vibration and the stochastic response to a white noise or a filtered white noise ground acceleration is determined by using the method of equivalent linearization. The sensitivity of the stochastic response to principal pàrameters for the bridge is investigated. Results of optimum design of the isolation system are presented.     

Dynamic response of a three-beam system with intermediate elastic connections under a moving load/mass-spring

The objective of this research is to study the dynamic response characteristics of a three-beam system with intermediate elastic connections under a moving load/mass-spring. In this study, the finite Sine-Fourier transform was performed for the dynamic partial differential equations of a simply supported three-beam system (SSTBS) under a moving load and a moving mass-spring, respectively. The dynamic partial differential equations were transformed into dynamic ordinary differential equations relative to the time coordinates, and the equations were solved and the displacement Fourier amplitude spectral expressions were obtained. Finally, based on finite Sine-Fourier inverse transform, the expressions for dynamic response of SSTBS under the moving load and moving mass-spring were obtained. The proposed method, along with ANSYS, was used to calculate the dynamic response of the SSTBS under a moving load/mass-spring at different speeds. The results obtained herein were consistent with the ANSYS numerical calculation results, verifying the accuracy of the proposed method. The influence of the load/mass-spring’s moving speed on the dynamic deflections of SSTBS were analyzed. SSTBS has several critical speeds under a moving load/mass-spring. The vertical acceleration incurred by a change in the vertical speed of SSTBS due to the movement of mass-spring and the centrifugal acceleration produced by the movement of massspring on the vertical curve generated by SSTBS vibration could not be neglected.     

结构非线性随机地震非零均值响应分析

本文讨论了随机等价线性化方法（ESL）作为一种对考虑力学参数随机性的非线性滞回结构进行可靠性分析的工具具有的灵活性，这种方法还被推广用来处理由于重力荷载的影响导致滞回曲线非对称引起的零平均输入非零平均输出的响应过程，利用此方法分析了一座按8度要求设计的钢筋混凝土规划框架结构和不规则框架，本文提出的方法可以分析范围更广泛的问题。     

结构平稳随机地震反应时域分析:应用

以平面框架结构为例阐述了结构平稳随机地震反应时域分析方法的应用。首先利用静力凝聚方法大幅度地缩减结构的自由度数目，形成一维链状模型，使得结构运动方程中只包含各层反应从而大大降低计算工作量。其次推导了结点随机反应和层间随机反应的计算公式，可以方便地获得结构在理想白噪声、金井清谱和改进金井清谱三种随机地震地面运动激励下的协方差位移反应函数和协方差速度反应函数。最后通过一个单跨双层的平面框架结构实例，阐述了这种方法的使用过程。     

基于概率密度演化的基础隔震结构随机响应分析

针对抗震结构和基础隔震结构,应用概率密度演化方法对其进行多遇地震作用下的线性随机响应分析.通过引入工程地震动物理随机函数模型,采用数论选点法对多维外荷载随机变量进行离散代表点的生成并求得其赋得概率,利用离散代表点合成地震动加速度时程样本作为输入结构的随机激励,对于每条地震波,相当于对结构进行确定性动力反应分析.在求得结...     

结构平稳随机地震反应时域分析:方法

给出了三种常用的随机地震地面运动过程模型,即理想白噪声模型、金井清模型、改进金井清模型的相关函数表达式.引入状态向量,在状态空间中建立地震地面运动激励下的结构振动方程,并求解出结构的复模态特性和复模态反应.利用复模态叠加法推导出线性时不变多自由度体系在这三种随机地震动激励下的平稳协方差反应的解析式,可在时域内直接计算结构随机反应的统计特征.该方法物理概念清晰,结论简便明确,可作为实际工程结构平稳随机地震反应的实用分析方法.     

考虑行波效应的车桥系统地震响应分析

借助虚拟激励法,本文研究了非一致水平地震作用下三维车桥耦合时变系统的非平稳随机振动问题。通过轮轨间位移协调关系将列车和桥梁运动方程进行耦合,建立了考虑行波效应的多点地震激励下列车-桥梁时变系统运动方程。水平地震激励假设为均匀调制多点异相位完全相干随机激励;轨道不平顺激励假设为多点异相位完全相干平稳随机激励。采用时变系统的虚拟激励法将这些随机激励分别转化为一系列虚拟的确定性激励,然后通过数值积分求解相应的虚拟响应,进而方便地得到系统随机响应的时变功率谱密度函数和标准差等。数值算例中,通过Monte Carlo法验证了本文随机振动分析方法的正确性和有效性,并讨论了地震波视波速、场地土条件等对系统随机响应的影响。     

Prediction of the measured response of a scaled soil-pile-superstructure system

The validity of the Winkler foundation model is investigated by predicting the experimentally measured displacement transfer functions and strain spectra of a single pile embedded in a sandbox and supporting a single-degree-of-freedom superstructure. The foundation-superstructure system is a scale model and was subjected to shake table excitations. The distributed springs and dashpots of the Winkler foundation model are frequency dependent and the calibrated model predicts satisfactorily the displacement transfer function at different depths for both fixed- and free-tip pile conditions. On the other hand, the pile-axial-strains are substantially underestimated when expressed in terms of the second derivative of the computed elastic line of the pile. It is shown that a much more dependable prediction is achieved when pile-axial-strains are expressed in terms of the inertial forces acting along the pile-superstructure system.     

Identification of force from response data of a nonlinear system

Force identification is a type of system identification procedure which determines applied force from system responses; it has engineering applications where direct measurements of forces are not feasible. To identify the force, one can consider that the system model and its parameters are known, and then use the measured response of the system to determine the unknown forces. In contrast, postulating the system model and its parameter values is a difficult task, especially when considering a nonlinear system where the model poses many unknowns or inherent mathematical problems. In this research, a more direct way to identify the unknown force without knowing the model of the system is proposed. The approach, called the sum of weighted acceleration technique (SWAT), is a method that can predict input forces with measured linear and nonlinear structural responses. SWAT employs measured accelerations multiplied by effective or optimal weights to estimate the input force. Results using this method show that the force calculated using SWAT accurately predicts the force which excites a nonlinear structure response. The technique could be applied to both constrained and unconstrained structures.     

Periodic response of a sliding oscillator system to harmonic excitation

This paper deals with the periodic response of an oscillating system which is supported on a frictional interface. The base excitation is assumed harmonic and the frictional force is assumed to be of the Coulomb type. Though each segment of the motion of such a system is described by linear equations, its complete response is highly non-linear and varied. The most fundamental periodic solutions are derived analytically and numerically. The results indicate that such a system has several subharmonic resonant frequencies and that while the friction reduces the peak response of the system when it is excited at its ‘fixed-base’ natural frequency, ω_n, the sliding can induce considerably higher levels of response, when compared with those of a non-sliding, fixed-base system, for frequencies less than ω_n. The results obtained herein may find application in the area of vibration isolation.     

Seismic response controlled structure with Active Variable Stiffness system

The Active Variable Stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural characteristics, such as stiffness of a building, to establish a non-resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate practical data and investigate them, a building has been constructed as a trial. This paper describes the applied system, the control algorithm, verification of stiffness selection, results of tests for verifying system characteristics, some observed earthquake records and simulation analyses. Responses in controlled and uncontrolled states have been compared to show the effectiveness of the proposed system.     

感应测井响应的非正交计算方法

由于在正交坐标系中斜度井边界处理的复杂性,提出一种非正交计算方法,即在非正交坐标系计算了斜度井中感应测井的响应.首先,利用Maxwell方程组和逐次逼近法推导出矢量电位在非正交坐标系下的解析解;然后,通过有限差分法计算接收线圈处的感应电动势,得到视电导率的值;最后,计算了无井无侵地层模型在不同厚度和倾斜角度影响下的响应,计算结果与理论解及前人结果具有很好的一致性.结果表明,该方法具有数值网格与边界吻合的特点,而且只要较少的离散网格就可以达到较高的精度,计算速度快,是求解斜度井中感应响应的有效方法.