Systems framework for fuzzy sets in civil engineering

Civil engineering projects and designs are commonly developed in a systems framework that includes different types of uncertainty. In general, uncertainty can be of the ambiguity or vagueness type. The theory of probability and statistics has been extensively used in civil engineering to deal with the ambiguity type of uncertainty. The theory of fuzzy sets and systems have been used in civil engineering to model the vagueness type of uncertainty in many civil engineering applications. In this paper, the role of fuzzy sets in civil engineering systems is described using several example applications, e.g., quality assessment of wildlife habitat, construction engineering and management, structural reliability, and damage assessment of existing structures.     

A review of major paradigms and models for the design of civil engineering systems

In this paper, the author presents the five classical paradigms of the process of design in civil engineering and identifies a new emerging paradigm: the interactive multi-attribute learning paradigm. This paradigm is studied in terms of actors, structures and OR instruments which can help to fulfil its application to modern design of civil engineering systems.     

Elastic buckling loads and fission critical mass as an eigenvalue of a symmetry breaking bifurcation

An instructive analogy is developed between two subjects of considerable applied importance in civil engineering namely buckling instability of the Euler elastica and the critical mass for neutrons diffusion.     

土木工程投标报价风险补偿费用的研究

基于模糊集理论，AHP原理以及土木工程投标承包的系统性和程序性特点，建立起工程风险之间存在可依赖性的风险分析模型，为风险补偿费用的确定提供较为科学的依据。     

The role of fuzzy sets in civil engineering

Civil Engineering is an art, the practise of which requires the use of scientific knowledge as a basic tool. The engineer has to use considerable judgement in setting up and interpreting his scientific calculations and in making decisions based upon incomplete information. Because a very high safety level is required in civil engineering structures the uncertainty associated with the application of scientific calculations is very crudely and conservatively estimated using traditional methods. Current reliability theory enables a discussion of random parameter uncertainty but in civil engineering, system uncertainty and the possibility of human error is extremely important and must be included in any reliability calculations.The potential role of fuzzy sets in analysing system and human uncertainty is discussed in the paper and two numerical examples are given of the calculation of system and random uncertainty using probability measures of fuzzy sets.     

Non-linear dynamic contact of thin-walled structures

In many areas of mechanical engineering contact problems of thin–walled structures play a crucial role. Car crash tests and incremental sheet metal forming can be named as examples. But also in civil engineering, for instance when determining the moment–rotation characteristics of a bolted beam–column joint, contact occurs. Effective simulation of these and other contact problems, especially in three–dimensional non–linear implicit structural mechanic is still a challenging task. Modelling of those problems needs a robust method, which takes the thin–walled character and dynamic effects into account. We use a segment–to–segment approach for discretization of the contact and introduce Lagrange Multipliers, which physically represent the contact pressure. The geometric impenetrability condition is formulated in a weak, integral sense. Choosing dual shape functions for the interpolation of the Lagrange Multipliers, we obtain decoupled nodal constraint conditions. Combining this with an active set strategy, an elimination of the Lagrange multipliers is easily possible, so that the size of the resulting system of equations remains constant. Discretization in time is done with the implicit Generalized-α Method and the Generalized Energy–Momentum Method. Using the “Velocity–Update” Method, the total energy is conserved for frictionless contact. Various examples show the performance of the presented strategies. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Time-dependent reliability assessment of structures using uncertain fractional rheological models

In this paper, a concept for time-dependent reliability assessment of civil engineering structures is presented. This concept bases on the uncertainty model fuzzy randomness. The time-dependent behaviour of materials with fading memory is captured by means of rheological models using uncertain fractional time derivatives. The presented method can be applied to the reliability assessment of engineering constructions. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Reliable Numerical Computation in Civil Engineering

Civil engineering is a field – as are many other engineering sciences – where most of the methods used for solving optimization problems are based on experience and experiments, and models using local information, but drawn from global models. The present work outlines an interesting class of problems from this field, and initiates some possible ways to solve those problems utilizing the wide tool capabilities of interval arithmetic for error handling and interval branch-and-bound algorithms to solve the original or modified industrial models automating civil engineers' work. The investigations are in the first state but are promising both in a theoretical and in a practical sense.     

考虑专家水平的土木工程质量综合评估模型

应用加权集值统计、属性数学和最小方差等方法 ,建立了考虑专家水平的量化综合评估模型 ,对土木工程质量进行多目标多人的综合评估 ,并给出计算实例 .     

Design of an optimal tuned mass damper for a system with parametric uncertainty

Structural control is becoming an attractive alternative for enhanced performance of civil engineering structures subject to seismic and wind loads. However, in order to guarantee stability and performance of structures when implemented with a passive or active control technique, there is a need to include information of uncertainty in the structural models due to the fact that civil engineering structures are time variant and nonlinear. These variations in the structure are often due to parameters such as variable live loads and inelastic behavior and, in cases, may be modeled as parametric uncertainty. The design of an optimal tuned mass damper (TMD) for a one degree-of-freedom (SDOF) system with parametric uncertainty is presented in this paper. The optimization of the connection between the absorber and the primary structure is cast as a constant feedback problem which is solved using structured singular value, μ, synthesis with D-K iteration and decentralized H _∞ design. Results are presented of the TMD that minimize the harmonic response of the primary structure represented by a set of systems within an uncertainty set.     

Modeling and evaluation of cyber-physical systems in civil engineering

A cyber-physical system (CPS) is a coupled system integrating computing, networking, and physical processes. Through actuation, cyber-physical systems control the physical processes, usually with feedback loops, where the physical processes affect computing and networking processes, and vice versa. In civil engineering, the most common fields of CPS applications are structural health monitoring (SHM) and structural control. A typical CPS task is the assessment of a structure based on (i) collected measurement data and (ii) a corresponding model. However, for an accurate and precise assessment of a structure, the CPS itself must be modeled and evaluated. In this paper, a conceptual modeling and evaluation approach is proposed, in which each part of a CPS is evaluated individually. In this study, the conceptual approach is presented for modeling and evaluation of CPS in civil engineering. The evaluation is based on an abstract approach allowing a discussion of a principle (i.e. general) model structure of a CPS, identifying critical issues to be studied in more detail in future research. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Three stage generalized flowshop: Scheduling civil engineering projects

We model the working of a civil engineering firm concerned with land development as a three stage flexible flowshop with weak chain precedence constraints and where preemption is allowed. The scheduling objective is to minimize the total tardiness for all the projects. Since solving this problem optimally is very hard, we propose a number of heuristic scheduling procedures which are evaluated extensively on real-life data and artificial problem instances.     

Multi-Dimensional Location Problems

A solution to the simple location problem is defined by a one-dimensional array of bivalent variables. Some multi-dimensional location problems may be also of interest in practice. Two such problems are analysed here. The first involves location of supply sources for several commodities and the second a multistage distribution system in which the location of demand varies from stage to stage. Examples of application from civil engineering practice are also presented.     

Simple calculation of moments of inertia for polygons

Recently the problem of finding the mass, centre of gravity and moments of inertia for laminae bounded by polygons arose in a programming course for first year civil engineering degree students. It was suggested that it would be useful for them to construct a program that would take as input the vertices of the polygon, and print out area, centroid and moment of inertia. In order to make the program have a logically simple structure, the method presented in this note was devised. After consultation with many standard textbooks and engineering handbooks it was discovered that the method was either original or completely neglected. Since in many respects the method compares favourably with the subdivision techniques of the standard sources it would appear to be worth publicising the technique.     

基于卓越工程师培养的高等数学教学策略

"卓越工程师教育培养计划"强调对学生工程实践能力、工程设计能力与工程创新能力的培养.高等数学是工科专业学生的必修基础课,它提供的数学思想、精神和思维方法以及理论知识不仅是后继专业课的重要工具,特别是在实践中培养学生工程能力和创新能力等方面发挥着非常重要的作用.文章根据卓越计划的培养理念并结合高等数学课程特点,探讨了高等数学教学策略.     

Adaptive reliability analysis based on a support vector machine and its application to rock engineering

The response surface method (RSM), a simple and effective approximation technique, is widely used for reliability analysis in civil engineering. However, the traditional RSM needs a considerable number of samples and is computationally intensive and time-consuming for practical engineering problems with many variables. To overcome these problems, this study proposes a new approach that samples experimental points based on the difference between the last two trial design points. This new method constructs the response surface using a support vector machine (SVM); the SVM can build complex, nonlinear relations between random variables and approximate the performance function using fewer experimental points. This approach can reduce the number of experimental points and improve the efficiency and accuracy of reliability analysis. The advantages of the proposed method were verified using four examples involving random variables with different distributions and correlation structures. The results show that this approach can obtain the design point and reliability index with fewer experimental points and better accuracy. The proposed method was also employed to assess the reliability of a numerically modeled tunnel. The results indicate that this new method is applicable to practical, complex engineering problems such as rock engineering problems.     

基于遗传算法的岩体参数辨识研究

目前,对于岩体流固耦合分析研究已经很多,而耦合分析常常受困于计算参数的取值,因此对两场耦合模型中的计算参数反演分析是非常必要的.根据实测的水头、位移资料,利用遗传算法,建立了等效连续岩体渗流场与应力场耦合计算参数辨识模型.并对某算例在库水位下降情况下,以渗流场与应力场耦合正分析计算结果作为"实测值",进行两场耦合参数辨识分析.从参数辨识的结果来看,验证了所提出的思路、方法以及程序的正确性和可行性.两场耦合计算参数进行反演分.析,对于两场耦合模型的建立和计算结果的可靠性是非常有意义的.     

Student Interest in Engineering Design‐Based Science

Current reform efforts in science education around the world call on teachers to use integrated approaches to teach science. As a part of such reform efforts in the United States, engineering practices and engineering design have been identified in K–12 science education standards. However, there is relatively little is known about effective ways of teaching science through engineering design. The study explores the approaches or strategies used by a sixth grade science teacher to teach science and engineering in an integrative manner. Classroom observations, teacher interview, and student surveys were used to study the features of engineering integration implemented by the teacher and the changes in student interest in science and engineering by participating in an engineering design‐based science unit. Findings suggest that the teacher explicitly included practices and core ideas from engineering and science; used an engaging, motivating engineering challenge; and provided students with opportunities to be autonomous. Students engaged in the activities in the engineering unit and their interest level slightly increased. The results suggest that the three strategies that the teacher used to teach engineering and science are important foundations of integrated science and engineering education.     

An Asymptotic-Homogenization Explicit Time-Domain Method for Random Multiscale Vibration Analysis of Porous Material Structures北大核心CSCD

由于具有高比强、高比刚度等优点,多孔结构在土木工程、机械工程和航天航空工程等领域得到了广泛应用.在随机动力荷载作用下多孔结构的随机响应分析是值得关注的研究方向之一.采用多尺度渐近均匀化法,推导了周期性多孔结构动力问题的多尺度控制微分方程,并建立了多孔结构宏观和细观动力响应的时域显式表达式.在此基础上,结合结构随机振动时域显式法,实现了非平稳随机激励下多孔结构动力响应统计矩的计算.所提出的渐近均匀化-时域显式法,一方面可以发挥多尺度动力分析渐近均匀化法的计算优势,高效建立多孔结构宏观和细观动力响应的时域显式表达式;另一方面也可以利用随机振动时域显式法的计算特点,快速精确地求解非平稳随机激励下多孔结构的随机振动问题.通过数值算例,验证了所提方法在多孔结构非平稳随机振动问题求解中的计算精度和计算效率.     

A Decision Model for a Sequential Testing Problem in civil Engineering

A sequential decision problem in civil engineering is formulatedas a dynamic programming model. A set of theorems lead to amore efficient formulation, permitting the solution routineto be programmed on a microcomputer. The solution is printedin table fonn, directly providing a decision rule usable bythe foreman in the field. The paper illustrates a point whichis becoming increasingly apparent: the power and availabilityof portable computer systems are making many decision problemsamenable to on-site analysis using models based upon rigoroustheory.