A unified formulation of the piecewise exact method for inelastic seismic demand analysis including the P‐delta effect     

M. N. Ayd&#x;nolu  Y. M. Fahjan 《地震工程与结构动力学》2003,32(6):871-890

The non‐linear analysis of single‐degree‐of‐freedom (SDOF) systems provides the essential background information for both strength‐based design and displacement‐based evaluation/design methodologies through the development of the inelastic response spectra. The recursive solution procedure called the piecewise exact method, which is efficiently used for the response analysis of linear SDOF systems, is re‐formulated in this paper in a unified format to analyse the non‐linear SDOF systems with multi‐linear hysteresis models. The unified formulation is also capable of handling the P‐delta effect, which generally involves the negative post‐yield stiffness of the hysteresis loops. The attractiveness of the method lies in the fact that it provides the exact solution when the loading time history is composed of piecewise linear segments, a condition that is perfectly satisfied for the earthquake excitation. Based on simple recursive relationships given for positive, negative and zero effective stiffnesses, the unified form of the piecewise exact method proves to be an extremely powerful and probably the best tool for the SDOF inelastic time‐history and response spectrum analysis including the P‐delta effect. A number of examples are presented to demonstrate the implementation of the method. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

A rooftop tuned mass damper frame     

Jerod G. Johnson  Lawrence D. Reaveley  Chris Pantelides 《地震工程与结构动力学》2003,32(6):965-984

This article documents the analytical study and feasibility of placing a tuned mass damper in the form of a limber rooftop moment frame atop relatively stiff structures to reduce seismic acceleration response. Six existing structures were analytically studied using a suite of time history and response spectra records. The analyses indicate that adding mass in conjunction with a limber frame results in an increase in the fundamental period of each structure. The fundamental period increase generally results in a decrease in seismic acceleration response for the same time history and response spectra records. Owing to the limber nature of the rooftop frames, non‐linear analysis methods were required to evaluate the stability of the rooftop tuned mass damper frame. The results indicate the addition of a rooftop tuned mass damper frame reduces the seismic acceleration response for most cases although acceleration response can increase if the rooftop frame is not tuned to accommodate the specific structure's dynamic behaviour and localized soil conditions. Appropriate design of the rooftop tuned mass damper frame can result in decreased seismic acceleration response. This translates to safer structures if used as a retrofit measure or a more economical design if used for new construction. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

System identification of linear structures based on Hilbert–Huang spectral analysis. Part 2: Complex modes     

Jann N. Yang  Ying Lei  Shuwen Pan  Norden Huang 《地震工程与结构动力学》2003,32(10):1533-1554

A method, based on the Hilbert–Huang spectral analysis, has been proposed by the authors to identify linear structures in which normal modes exist (i.e., real eigenvalues and eigenvectors). Frequently, all the eigenvalues and eigenvectors of linear structures are complex. In this paper, the method is extended further to identify general linear structures with complex modes using the free vibration response data polluted by noise. Measured response signals are first decomposed into modal responses using the method of Empirical Mode Decomposition with intermittency criteria. Each modal response contains the contribution of a complex conjugate pair of modes with a unique frequency and a damping ratio. Then, each modal response is decomposed in the frequency–time domain to yield instantaneous phase angle and amplitude using the Hilbert transform. Based on a single measurement of the impulse response time history at one appropriate location, the complex eigenvalues of the linear structure can be identified using a simple analysis procedure. When the response time histories are measured at all locations, the proposed methodology is capable of identifying the complex mode shapes as well as the mass, damping and stiffness matrices of the structure. The effectiveness and accuracy of the method presented are illustrated through numerical simulations. It is demonstrated that dynamic characteristics of linear structures with complex modes can be identified effectively using the proposed method. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Evaluation of predictors of non‐linear seismic demands using ‘fishbone’ models of SMRF buildings     

Nicolas Luco  Yasuhiro Mori  Yosuke Funahashi  C. Allin Cornell  Masayoshi Nakashima 《地震工程与结构动力学》2003,32(14):2267-2288

Predictors (or estimates) of seismic structural demands that are less computationally time‐consuming than non‐linear dynamic analysis can be useful for structural performance assessment and for design. In this paper, we evaluate the bias and precision of predictors that make use of, at most, (i) elastic modal vibration properties of the given structure, (ii) the results of a non‐linear static pushover analysis of the structure, and (iii) elastic and inelastic single‐degree‐of‐freedom time‐history analyses for the specified ground motion record. The main predictor of interest is an extension of first‐mode elastic spectral acceleration that additionally takes into account both the second‐mode contribution to (elastic) structural response and the effects of inelasticity. This predictor is evaluated with respect to non‐linear dynamic analysis results for ‘fishbone’ models of steel moment‐resisting frame (SMRF) buildings. The relatively small number of degrees of freedom for each fishbone model allows us to consider several short‐to‐long period buildings and numerous near‐ and far‐field earthquake ground motions of interest in both Japan and the U.S. Before doing so, though, we verify that estimates of the bias and precision of the predictor obtained using fishbone models are effectively equivalent to those based on typical ‘full‐frame’ models of the same buildings. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

A Linear Programming Approach to Determine the Normative Composition of Sedimentary Rocks     

V. N. Podkovyrov  O. V. Graunov  R. L. Cullers 《Mathematical Geology》2003,35(4):459-476

The analysis of modal and normative composition of sedimentary rocks is widely used for studying their sources and tectonic settings. The normative calculation of the mineral composition of rocks in this study is formulated as a linear programming problem and is solved by means of the simplex method. This enables both simultaneous and successive subtraction of a set of basic minerals from a rock sample represented by its chemical composition {SiO₂...LOI}. Such an approach provides a more exact calculation of the contribution of basic minerals in the rock. This mathematical approach is used to study two representative sets of sandstones and fine-grained rocks from a Meso- to Neoproterozoic marginal basin of southeastern Siberia (Uchur–Maya region, Yakutia) and a Pennsylvanian-Lower Permian uplifted continental block in Colorado, USA. The calculated normative mineral compositions of the Siberian sandstones are consistent with the observed modal compositions. These sandstones vary from K- Feldspar rich arkoses at the base of the sequence (the Uchur Group, lower Riphean) to quartz arenites or lithic sandstones and wacke in transgressive successions of the middle-upper Riphean. Arkoses and quartz arenites are dominant in Meso- to Neoproterozoic Siberia. These samples represent craton interior uplifted basement and quartzose, recycled orogen provenance of a stable craton in Rodinia. There are higher but consistent discrepancies between the calculated and observed compositions for the Pennsylvanian to Lower-Permian arkoses and quartz arenites (Sangre de Cristo, Belden, and Maroon Formations). The differences between the predicted and observed mineralogy may be due to uncertainties in the modes in the matrix and cement of the sandstones. This normative program should supplement modal calculations and provide better genetic constructions, especially in case of matrix-rich sandstones.  相似文献   

Smoothing and Change Point Detection for Gamma Ray Count Data   总被引：1，自引：0，他引：1  

Daniela Leonte  David J. Nott  William T. M. Dunsmuir 《Mathematical Geology》2003,35(2):175-194

Gamma ray detectors are used to measure the natural radioactivity of rocks. For a number of boreholes drilled at a site the gamma ray detector is lowered into each borehole and counts of gamma ray emissions at different depths are recorded as the instrument is gradually raised to ground level. The profile of gamma counts can be informative about the geology at each location. The raw count data are highly variable, and in this paper we describe the use of adaptive smoothing techniques and change point models in order to identify changes in the geology based on the gamma logs. We formulate all our models for the data in the framework of the class of generalized linear models, and describe computational methods for Bayesian inference and model selection for generalized linear models that improve on existing techniques. Application is made to gamma ray data from the Castelreagh Waste Management Centre which served as a hazardous waste disposal facility for the Sydney region between March 1974 and August 1998. Understanding the geological structure of this site is important for further modelling the transport of pollutants beneath the waste disposal area.  相似文献   

青藏高原上中尺度对流系统(MCSs)的个例分析及其比较   总被引：3，自引：0，他引：3  

ZHU Guofu  CHEN Shoujun 《大气科学进展》2003,20(3):311-322

对1995年7月25—28日高原上连续数日出现MCSs的现象进行了红外云图特征及其演变、大尺度环境背景场和对流有效位能的分析。可以发现，所有这些MCSs有着相似的日变化演变过程；它们的初始对流在中午由于日射加热开始活跃，之后迅速发展，这些MCSs在后下午形成，在傍晚达到最强，之后逐渐减弱。其中26日MCS最为强大，它是在单一的强大的近于圆形的高原反气旋高压背景下受强的低层热力强迫和条件不稳定的驱动而发生的。这些发生条件都与高原本身的热力作用紧密相关，所以它的发生发展主要与高原特有的较为纯粹的热力因子相联系。28日MCS是另一个很强的MCS，它明显地受到中纬度西风槽的斜压区的影响，这二个很强的MCS有着不同的发展机制和显著不同的表现特征。  相似文献   

声波测试中振子衰减的线列阵模型     

易南概  赵俭斌 《地震工程与工程振动》2003,23(2):81-84

从声波在岩体中传播产生衰减的基本原理出发，建立了声波衰减振子的线列阵模型。该模型是将传播声波路径的岩体分为若干个振子，从波动概念出发，以振动原理作依据建立波动方程．为探讨岩体声波衰减机制提供了一种新的研究方法，把振动和波动直观地联系起来．单一方向上有限点的声波测试技术有可能被多方向的声测技术所代替．该模型的建立，使模态分析和参数识别方法应用到岩体声波测试技术中成为可能。  相似文献   

非线性编辑与线性编辑在气象电视节目中的使用     

蓝设华  裴毅 《气象研究与应用》2003,24(3):46-47

通过对非线性编辑与线性编辑两者的概念及其特点、优势的介绍,指出在气象电视节目的后期制作中,怎样恰当地选择使用非线性编辑、线性编辑或二者同时使用。  相似文献   

n维非线性波动方程对应的线性方程Cauchy问题解的一个估计式     

郭华  李月  杨宝俊  刘财  杨冬  张景 《地球物理学进展》2003,18(1):142-145

对于地震波在地球介质中传播的传播非线性而言，在求解n维非线性波动方程Canchy问题时，需要求解其对应的线性波动方程Cauchy问题和建立一些解的估计式。我们已经求得了其对应的线性波动方程Canchy问题解的表达式。在此基础上，本文应用函数空间L^1(R^n)、L^∞（R）的范数，建立了n维非线性波动方程对应的线性波动方程Cancny问题解的一个估计式，为求解n维非线性波动方程莫定了基础。  相似文献