体系可靠指标对随机变量分布参数的敏感性

目前,在体系可靠指标对随机变量的敏感性分析中,没有考虑失效模式间的相关系数对随机变量的敏感性。针对这个问题,通过理论推导,得到了失效模式间的相关系数对随机变量的敏感性,进而修正了体系可靠指标对随机变量的敏感性表达式;根据敏感性定义及参考现行规范,提出了随机变量作为常量的判断标准。算例结果表明,修正的体系可靠指标对随机变量的敏感性表达式是正确的,提出的随机变量作为常量的标准是可行的。因此,本研究完善了体系可靠指标对随机变量的敏感性分析方法,为提高结构体系可靠指标的计算效率提供了理论依据。     

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.     

微分方程的分离变量法及实例分析

本文主要介绍了分离变量法求解微分方程的基本方法和适用条件,并通过几个应用事例展示了其重要性和现实意义.     

结构分析软件中的二次分析探讨

在结构分析中,有很多需要利用前一次的计算结果来确定下一次的计算参数以进行二次分析的情况,据此提出了结构二次分析的理念,二次分析的结果才是工程真正可用的计算结果。结合常用结构分析软件,从结构整体分析、具体结构类型和结构构件三个层次详细阐述了在结构分析中需要进行二次分析的原因和依据,并对具体设计给出了操作性强的实用方法,以期对今后更准确地利用结构分析软件进行结构设计提供一些有益的借鉴。     

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.     

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.     

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...     

Fuzzy Clustering of Stability Diagrams for Vibration-Based Structural Health Monitoring

Abstract:   A primary challenge to implementing structural health monitoring techniques on civil infrastructure is the identification of structural changes in the presence of natural changes in structural response due to environmental variables such as temperature. Data from the Z24 Bridge recorded over the course of nearly a year are analyzed in this article. Covariance-driven Stochastic Subspace Identification is applied to the data to identify the modal parameters of the structure. A large number of numerical poles are identified with the real physical poles. A Fuzzy Clustering Algorithm is then used to extract parameters indicative of the bridge's state from the mixture of real and numerical poles. The main benefit of this approach is the lack of need for mode shape information and thus its applicability to structures monitored with spatially sparse sensor grids. The method is shown to provide very encouraging results in separating the response data from the Z24 Bridge in healthy and damaged states in varying environmental conditions. The method does not explicitly identify the changes due to environmental variables but it is found that the changes in the parameters identified due to damage are greater than those due to environmental variability and therefore may be flagged. The procedure is also applied successfully to a second data set obtained from monitoring a tall building over several years of its early life to identify gradual or sudden structural changes.     

钢结构安装工程质量的模糊综合评判研究

提出了采用模糊综合评判对钢结构安装工程质量进行检验评定的方法。与现行方法相比,该方法能更客观地表达工程实际的质量状况,有利于定量化评定工程质量,实现检验评定的计算机管理。     

含结构面板岩变形特征分析

在三轴压缩实验基础上,研究含一组结构面的板岩在不同湿度与压力下的力学特性及变形规律,利用Hoek-Brown强度准则分析了板岩的破坏特征,建立了相应的岩体强度准则与力学参数求取方法;利用FLAC程序模拟计算了不同埋深条件下板岩岩体中开挖隧洞后洞周变形规律,分析了岩体变形特征.研究结果表明:1)基于Hoek-Brown准则建立了含结构面的板岩岩体强度破坏准则,确定出的不同地质条件下板岩岩体力学强度参数;2)扰动程度对岩体强度参数有较大的影响,且影响程度随着隧洞埋深的增加而增大;3)数值模拟结果显示,西线工程软岩隧洞的围岩变形主要受开挖断面、埋深及物理力学参教等多因素的影响.     

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。     

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。     

Damage Pattern Recognition for Structural Health Monitoring Using Fuzzy Similarity Prescription

Abstract:   Structural health monitoring (SHM) is a systematic method for non-destructive evaluation of a structure's performance by sensing, extracting, patterning, and recognizing features of the structural response. Most SHM approaches focus on statistical analysis for damage identification considering only random uncertainties. This article introduces a method that allows accommodating other types of uncertainties due to ambiguity, vagueness, and fuzziness which are statistically non-describable. The proposed method deals primarily with epistemic uncertainty. The method improves damage identification by performing damage pattern recognition using fuzzy sets. In this approach, healthy observations are used to construct a fuzzy set representing healthy performance characteristics. Additionally, the bounds on the similarities among the structural damage states are prescribed. Thus, an optimal group of fuzzy sets representing damage states such as little, moderate, and severe damage can be inferred as an inverse problem from healthy observations only. Piecewise linear functions are used as fuzzy membership functions representing the states of healthy and damaged. The optimal group of damage fuzzy sets is used to classify a set of observations at any unknown state of damage using the principles of fuzzy pattern recognition based on maximum approaching degree. A case study for damage pattern recognition of a model steel bridge is presented and discussed. The approach is capable of identifying damage patterns accurately.     

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。     

基于三维变量的物流外包合作博弈分析

第三方物流服务需求方与提供商之间的合作对提高整个物流外包的绩效十分重要,但在物流外包过程中,第三方物流服务提供商的资产能力、管理水平与努力水平三因素均为非对称信息。在此基础上,建立第三方物流服务需求方与提供商之间的合作博弈模型,利用委托-代理理论和最大值原理求解得出博弈双方的合作策略;在代理人为风险中性的假设下,进一步分析物流外包方的风险成本、激励成本和总代理成本。结果表明：物流服务提供商的资产能力、管理能力以及努力水平,在物流外包中起到关键的作用。     

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