Calibration of Structural Models Using Fuzzy Mathematics

Abstract: A calibration model is presented that quantifies the uncertainties associated with structural free vibration analysis. System identification objectives and fuzzy set mathematics are integrated to formulate an analysis methodology that enables the a priori prediction of the most probable sources of modeling error. By first developing fundamental fuzzy sets defining uncertainty in structural parameters such as stiffness and design loading, higher-level fuzzy sets governing dynamic behavior are obtained using the vertex method. Uncertainty in the dynamic parameters (natural frequency, frequency ratio, and structural response) are each represented using fuzzy mathematics, where membership functions are determined by performing multiple dynamic analyses involving confidence levels of model assumptions. A numerical example is presented to demonstrate the calibration model for a 13-story steel structure located in San Jose, California. Results show that the calibration model is capable of quantifying uncertainties in structural properties and behavior without requiring the measured data necessary for conventional system identification procedures.     

An Integrated Fuzzy Control System for Structural Vibration

Abstract:   Recently, numerous studies of structural control systems of civil structures and infrastructure have been carried out. To develop structural control systems, it is necessary to consider their special features such as complexity, uncertainty, and size. To consider these features, fuzzy theory has been applied to structural control systems. This study proposes an integrated fuzzy active control system based on fuzzy ensemble learning. It combines several fuzzy active control systems and improves structural vibrations caused by earthquakes. The proposed method includes two fuzzy active control systems, a fuzzy ensemble system, and a gating network. In this study, two fuzzy active control systems are constructed by applying particle–swarm optimization. The fuzzy ensemble system assigns a performance grade to each fuzzy active control system according to control effects from input patterns. The gating network determines the final control force based on the weight of their performance grade. By introducing fuzzy ensemble learning, the structural response is reduced more than when the response is controlled by individual fuzzy active control systems.     

Identification of Fuzzy Relations with Multiple Hyperplanes by Genetic Algorithm in Structural Design

Abstract: This paper proposes a method for formulation and quantification of human subjective evaluations and uncertain numerical values by using multiple hyperplanes based on the results of questionnaires distributed to structural designers that are composed of four questions about structural design and planning, i.e., ( Q 1) structural damage , ( Q 2) structural economy in a macroscopic sense , ( Q 3) structural safety, and ( Q 4) opening patterns in facade. In this paper, some hyperplanes in multidimensional spaces are used as a method to identify fuzzy relations (states) in intelligent fuzzy networks for seismic structural planning. A genetic algorithm is employed as a search method for optimal formulations and is proved to be very effective as a method for such an identification.     

一种强化抗风及抗震式高层标志塔结构的设计研究

以某海洋王国的标志塔为例子,提出一种具有结构刚度大、抗风及抗震能力强特点的高层标志塔结构体系,并且建立模型,验算结构体系的合理性。结果表明该结构变形和强度均满足要求,各项计算指标良好,有效地解决现有的高层标志塔结构存在结构刚度低、耐地震能力差等问题,为同类型工程提供参考。     

八连杆叉装机产品结构分析

随着国内物流行业的迅速发展,市场物流量大幅增长,大量使用诸如40ft高柜集装箱、高护栏货车、后方装卸的长型或超长型厢货车,这些集装箱或车辆均要求有高举升、大伸距且具有机具平移功能的叉装机械与之配套.但长期以来,可供选择的仅有伸缩臂叉装机,为此国内厂商纷纷推出一些在装载机基础上改装而成的连杆式叉装机,但都算不上真正意义上...     

带水平加强层的超高层结构的力学性能分析

本文对带遥若干水平加强层的钢框架－混凝土核心筒超高层结构进行了三维有限元内力、动力响应计算分析,并进行多种不同结构布置的比较、分析。总结出水平加强层对钢－混凝土超高层结构的几个力学方面性能的影响程度。     

单层抽柱钢结构厂房的结构分析

由于主厂房局部抽柱,形成了最大36m的柱距,并且使得布置均匀的柱网局部削弱,出现薄弱部位。本文以抽柱排架作为研究对象,分别计算标准单元排架、抽柱后中柱计算单元、抽柱后边柱计算单元,三种模型进行分析对比,找出抽柱后结构构件的内力变化。     

圆孔鸟巢形网架结构的分析

基于铁摩辛柯梁理论,采用连续化数学模型和角度位移法,对鸟巢形网架结构的内力和变形进行分析,提出了简化计算方法。算例分析结果表明,提出的计算方法概念清楚,计算简单,结果精确度较高。     

混合变量min—max型工程优化设计方法

阐述了一种混合变量ｍｉｎ－ｍａｘ型工程优化设计的方法，并以砼泵车为例说明了这一方法的优越性。     

模糊综合评判方法在建筑结构选型中的应用

考虑造价、工期等指标的结构选型决策过程虽已取得了一定进展,但因为决策分析方法理论成分高、量化指标不明确,所以应用于工程的报道并不多见。本文结合工程实例分析模糊综合评判方法辅助决策的量化计算过程。结果表明,当权重集随经济形势的变化而改变时,会得出不同的决策结论。本文的计算方法和结论可为设计人员及房地产管理人员在结构选型决策中借鉴和参考。     

含结构节点的地铁车站空间受力分析

南京地铁一号线某车站一、二号线换乘站 ,地铁二号线区间和规划的公路隧道斜交穿过车站地下二层 ,车站节点多 ,结构受力复杂。采用传统的平面简化法显然难以确定车站各种构件受力情况。本文提出采用梁 板 柱空间单元模型 ,利用通用程序ALGOR ,对车站进行空间受力分析 ,并将结构节点处梁、板、柱内力与一般地段进行比较 ,为车站结构设计提供依据     

浅析多层大跨超长混合建筑结构设计

近年来,多层大跨度建筑结构在我国得到了长足发展,呈现了越来越多的建筑种类,样式繁多,并不断创新和进步.文章以多年发展为基础,对超长混合建筑结构进行分析,对各类建筑风格进行了重点阐释,表明在空间建筑上我国已经取得了突破性的成就.     

结构的数学建模分析方法

提出结构拓朴和几何的一般规律及其抽象的方法,引入整型名义坐标系,并在该坐标系下,利用指示矩阵对抽象结构进行描述。     

Parallel Structural Analysis Using Threads

Practical solution of the structural analysis problem in a parallel processing environment is investigated through the use of the notion of cheap concurrency and the concept of threads. A thread is a lightweight process or independent instructions executing agent capable of concurrent execution with other threads. Portions of a structural analysis code implemented in C have been parallelized employing the Encore Parallel Threads on an Encore Multimax multiprocessor computer. The issues of racing condition, synchronization, and mapping are considered and discussed. Two synchronization mechanisms, semaphores and monitors, have been employed and compared. Two different mapping strategies have been implemented and studied. Results are reported on the effect of amount and frequency of shared memory access on the speed-up, the overhead time required for creating threads, and comparison of overall computational time performance using two space truss examples. An overall efficiency of 90–95% was achieved for 11 processors.     

燃气输配管网结构分析中的结构因素

燃气输配管网的压力级制、管网型式、阀门配置和管径配置等是管网结构因素。分析了管网结构分析的目的和方法,探讨了各管网结构因素。     

城市燃气管道模糊聚类分析

模糊聚类分析是在模糊分类关系基础上进行聚类，其基本思想是用相似性尺度来衡量事物之间的亲疏程度，并以此来实现分类。在详细分析影响燃气管道外腐蚀的主要因素的基础上，通过现场调研打分法建立初始评价矩阵．再根据模糊聚类的数学方法将初始矩阵转化为可以直接进行模糊聚类分析的模糊等价矩阵，然后通过模糊等价矩阵对管道进行聚类分析。     

岩土参数对桩基性能影响的随机有限元分析

将岩土材料参数作为随机变量来考虑,通过现场勘探取原状样,进行土工实验,结合经验资料,确定岩土材料参数分布函数。用蒙特卡罗随机有限元法分析随机变量对桩基工作性能影响的敏感性,如桩端应力、位移。得到影响单桩桩端位移、桩端应力最显著的因素均是桩土间粘聚力,其次是桩土间摩擦因数。并且桩端位移、应力与桩土间粘聚力、摩擦角均呈负线性关系。     

Verification Tests for Computer-Aided Structural Analysis

This paper proposes a sequence of independent analyses for verifying the accuracy of the numerical analysis of a structure. The tests separately assay the approximations of round-off logic, discretization, and idealization on a quality-assurance basis. Because these tests require no special simulation logic, they are suitable for use with public domain software.
The tests provide necessary checks of the accuracy of response predictions for the structure of immediate interest. Most tests are self-consistency checks which detect the sensitivity of results to changes in the problem definition and hence for changes of computer precision, computer logic, grid size, and idealization parameters. Some of the tests simply involve scaling responses.
Use of the tests for a simple problem illustrates the verification process and interpretation of test results. Comparisons with exact analysis results suggest that the tests can play an important role in increasing the reliability of numerical structural analyses.     

新型可展开板索壳体结构模型的研究和分析

基于现有可展结构在实际运用中存在的不足,提出了一种新型的可展结构形式,即板索壳体结构.该结构以三铰拱作为结构形式的基础,通过限制结构的自由度和提高结构刚度,使结构的承载力和稳定性得到提高.板索壳体结构具有容易收展、便于运输、构件简单、易于加工、可供大跨度空间使用等优点.通过理论结合试验的方式对板索壳体结构模型的性能进行了探究,认为该结构具有一定的工程应用前景.