A fuzzy logic approach to model delays in construction projects using rotational fuzzy fault tree models

Delays in construction projects are inevitable and, as a result, claims and disputes arise. Different causes of delay can come into play and therefore the need to identify and classify different causes of project delay arises. Different factors that contribute to project delay affect the likelihood of project delay in different degree of effectiveness. Fuzzy fault tree analysis (FTA) is suggested by this research to estimate the likelihood of project delay. Likelihood of delay membership function is further quantified using the weighted average defuzzification method. Two fuzzy logic models are implemented into the fuzzy FTA, using Visual Basic software: the models discussed in this research are Baldwin's rotational model and the Angular model. Comparison between the two fuzzy logic models has been carried out. Validation of the fuzzy FTA computer model is performed. Validation of the model was performed for adequacy and applicability of the model. On average, the validation performed by independent construction engineers and fuzzy logic experts produced satisfactory results. The computer software suggested by this study is an attempt to assess the likelihood of the project delay, which helps reduce delays in construction projects that can cause time loss.     

Analysing factors affecting delays in Indian construction projects

Construction projects in India are experiencing widespread delays. Due to a dramatic shift in the capacity and volume of the Indian construction sector over the last decade, the need of a systematic analysis of the reasons of delays and developing a clear understanding among the industry professionals are highly crucial. Using a selected set of 45 attributes, this research first identified the key factors impacting delay in Indian construction industry and then established the relationship between the critical attributes for developing prediction models for assessing the impacts of these factors on delay. A questionnaire and personal interviews have formed the basis of this research. Factor analysis and regression modelling were used to examine the significance of the delay factors. From the factor analysis, most critical factors of construction delay were identified as (1) lack of commitment; (2) inefficient site management; (3) poor site coordination; (4) improper planning; (5) lack of clarity in project scope; (6) lack of communication; and (7) substandard contract. Regression model indicates slow decision from owner, poor labour productivity, architects' reluctance for change and rework due to mistakes in construction are the reasons that affect the overall delay of the project significantly. These findings are expected to be significant contributions to Indian construction industry in controlling the time overruns in construction contracts.     

基于Choquet模糊积分的工程投标风险评估方法

在工程项目竞争性投标中,对于承包商来说,投标决策是一个多风险因素综合评价的问题,既要考虑自身实力,业主情况等主观条件,又要考虑项目的复杂性、自然条件等客观条件,同时还要兼顾经济、社会、环境、安全等各种因素。结合我国当前建设市场的现状和国内外相关文献,构建了工程项目投标风险因素评估系统层次结构和指标体系。针对在多因素指标的综合评价问题上,建立相互独立的指标比较困难和人们的主观评价往往存在非线性的特点,在模糊测度的基础上,提出一种基于Choquet模糊积分的新的工程投标多风险因素综合决策算法,详细论述该算法的计算步骤,并通过案例验证该方法的可行性、有效性和实用性。结果表明,该方法可以对多个项目进行投标风险评估排序,并且计算简单,可适用多种综合评价问题。     

Distilling and managing engineers' experience in construction projects using a pattern approach

Construction management requires engineers to acquire effectively and efficiently management experience. Most experience management (EM) in the construction industry focuses on explicit experience (such as writing reports and documents). Furthermore, tacit experience is usually more difficult to acquire than explicit experience. This study proposes an After the Issue Review (AIR) approach to acquire experience from engineers involved in construction projects, and effectively enhance experience sharing through a web‐based platform. Moreover, an AIR Construction Pattern (AIRCP) scheme is proposed and utilized to codify and edit the acquired experience. The web‐based experience management system presents a user‐friendly interface of an experience‐sharing platform, through which engineers learn valuable tacit experience derived from previous projects. Finally, a case study involving tunnel construction for expressway projects in Taiwan is utilized to validate the proposed approach and demonstrate the effectiveness of experience acquisition and management in construction.     

The use and limitations of mathematical models in the planning and control of construction projects *

The two major parameters associated with the planning and control of construction projects are time and cost. Modelling these parameters separately presents many difficult problems. The problem of optimizing the relationship between the two is even more complicated and earlier researchers have suggested a variety of models.

Models are, in a sense, an attempt to initiate a systems approach to problem solving and decision making. The aim is to try to capture the major components and the interactions of a system. Having developed the model it is possible to obtain valuable insights into the behaviour of a system with possibilities of optimizing its performance. This paper considers the general problem of modelling time and cost and examines some of the conditions and limitations of the modelling process.

The overall objective of this series of papers is to find not only a way in which the time cost parameters can themselves be modelled in dynamic and reasonably precise terms, but also to demonstrate the ways in which time and cost are inter-related and how the inter-relationship changes with the expansion or the diminution of the two parameters. The ability to capture and respond to the dynamic nature of the situation has been considerably enhanced by advances in computer technology, particularly in terms of the relatively low cost and interactive nature of the micro-computer.     

A critical discussion of models for conceptualizing the economic logic of construction

The construction industry has developed a certain economic logic that reflects the way in which tasks, parts, and units are organized and related to each other in order to create economic benefits in the construction process. Four different models in the literature portray this logic. We examine how they complement and constitute alternatives to understandings of the economic logic of the construction industry. Along with transaction cost economics, we have identified three more empirically based models: a project-oriented model, a supply-chain-oriented model, and a network-oriented model. Associated with different streams of research, these models are discussed in terms of the typical problems and key interdependencies in the construction process they address, and the type of solutions they suggest, including organizing principles for how construction parties should relate to each other. The findings show how examining different models provides a comprehensive, albeit non-exhaustive overview and an explanation of why the construction process is organized in the way it is. There is a need for increased awareness of the utilization of models (or combinations of models) and the models must also be seen as arguments in a broader discussion of how the construction process could or should function.     

基于熵权的模糊分析法在风险管理中的应用

在分析建设项目风险管理的基础上,结合模糊数学中层次分析法和熵权的概念,建立了熵权模糊分析模型。针对建设项目中的风险因素,提供了管理决策的依据,以正确的进行项目风险的管理和决策工作。     

钢筋混凝土施工质量综合评价的模糊可变评价模型

将模糊可变评价模型应用于钢筋混凝土施工质量评价研究中,建立了钢筋混凝土施工质量评价的模糊可变评价模型.选取模板工程、钢筋工程、混凝土工程的施工质量为评价指标,评价钢筋混凝土施工质量程度.研究表明:模糊可变评价模型误判率低,识别正确率达高,是钢筋混凝土施工质量程度判别与分类的一种有效方法,可在钢筋混凝土施工质量程度的工程...     

A fuzzy approach to construction project risk assessment

The increasing complexity and dynamism of construction projects have imposed substantial uncertainties and subjectivities in the risk analysis process. Most of the real-world risk analysis problems contain a mixture of quantitative and qualitative data; therefore quantitative risk assessment techniques are inadequate for prioritizing risks. This article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement, and on the Analytic Hierarchy Process (AHP), which is used to structure a large number of risks. The proposed methodology incorporates knowledge and experience acquired from many experts, since they carry out the risks identification and their structuring, and also the subjective judgements of the parameters which are considered to assess the overall risk factor: risk impact, risk probability and risk discrimination. All of these factors are expressed by qualitative scales which are defined by trapezoidal fuzzy numbers to capture the vagueness in the linguistic variables. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are necessary, and the use of trapezoidal fuzzy numbers until the defuzzification step. An illustrative example on risk assessment of a rehabilitation project of a building is used to demonstrate the proposed methodology.     

施工方案评价中的多级模糊优化及非结构性模糊决策分析

选择合理的施工方案是单位工程施工组织设计的核心。针对施工方案评价中影响因素复杂及非结构性因素量化等难点问题,提出了将多因素、多级非结构性模糊优选理论应用到施工方案比选中。采用四级模糊优选模型,综合考虑了影响施工方案比选的各种目标,并针对主观性较大的评价因素,引入非结构性模糊决策法和优先关系法,以确定其隶属度和权重。通过此模糊优选模型,进行了施工方案的优选,得到了比较理想的优选结果,证明了此模型在施工方案评价中的实用性。     

Using fuzzy multiple criteria decision making approach to enhance risk assessment for metropolitan construction projects

The undertaking of construction projects in metropolitan areas is a risky, competitive, and dynamic proposition requiring a reliable risk assessment model for adequate planning. This study employs a fuzzy multiple criteria decision making (FMCDM) approach to systematically assess risk for a metropolitan construction project. Consistent fuzzy preference relations (CFPR) are used to measure and investigate the relative impact on project performance of twenty identified risk factors included in four risk dimensions. The fuzzy multiple attributes direct rating (FMADR) approach is employed to analyze the occurrence probability of multiple risk factors. Furthermore, the level of risk for the overall project caused by individual risk factor is evaluated with the synthesized analysis of the relative impacts and probability of occurrence. The implementation of FMCDM makes the proposed risk assessment approach more reliable and practical than the traditional statistical approach. The proposed approach can be employed to effectively evaluate the overall project risk, and can be benefited to efficiently identify significant risks of a metropolitan construction project.     

在建设工程中该如何履行安全监理

针对建设工程中如何履行安全监理进行了探讨,分别阐述了对建设监理的认识、监理范围和授权、技术监督检查等五方面内容,指出搞好安全监理意义重大,应牢固树立以人为本,安全发展理念,不断加强安全监管力度。     

建设项目员工责任心对安全行为的影响

建设项目中,人的不安全行为是导致事故发生的最主要原因之一,本研究旨在研究建设项目员工责任心对其安全行为的影响。首先,基于文献研究构建责任心直接与间接影响安全行为的结构方程假设模型并提出工龄对责任心影响安全行为的调节效应假设;其次,在国内九个典型建设项目上收集数据,对上述结构方程模型及调节效应假设进行验证,发现在建设项目中责任心能直接促进遵守性安全行为,并能以安全文化为媒介间接促进遵守性安全行为和参与性安全行为,而责任心对两种安全行为的影响均受到工龄的调节作用;最后,对研究结果进行分析、探讨,结合员工工龄特征,从提升责任心的角度对建设项目安全管理提出有针对性的措施,并促使项目更有效地利用各项资源,以最大限度地改善建设项目的安全绩效。     

A fuzzy logic model to predict specific energy requirement for TBM performance prediction

Prediction of tunnel boring machine performance is a critical key for successful tunnel excavations. Specific energy requirement of disc cutters, which is defined as the amount of energy required to excavate a unit volume of rock, is one of the important parameters used for performance prediction of these machines. Much research has been conducted to predict cutting parameters of disc cutters using analytical, empirical and numerical approaches. In recent years alternative methods, such as fuzzy logic, have been extensively used to deal with subjects having ambiguities and uncertainties. In this study, a model was established to predict specific energy requirement of constant cross-section disc cutters in the rock cutting process by using fuzzy logic method. This model is based on experience and the database which consists of linear cutting test results that were generated over for many years at the Earth Mechanics Institute of the Colorado School of Mines. The model predicts specific energy requirements of disc cutters using uniaxial compressive and tensile strength of rocks, disc diameter and tip width, penetration and spacing of cuts.     

Approximation approach for personal estimation in safety analysis of existing structures

Different studies in recent years show that many structural failures are due to errors in planning, design, construction and utilization. These are difficult to quantify and have not been considered in probabilistic design methodologies (reliability theory). In practice the designer must use his practical experiences, the actual conditions and the pure speculations when evaluating safety factor values. Therefore, the reliability of structures is not only an objective but also a subjective concept, which is a property of the designer's state of knowledge. They need a way of combining all the subjective information, which are of multivalued nature and come from multiple sourcesof estimates.

In this study an inferential method applying fuzzy set and fuzzy logic to analyze safety of the existing structures is presented.     

Application of fuzzy logic in internal combustion engines to predict the engine performance

This paper describes an application of fuzzy logic principle for predicting the internal combustion engine performance, emission and combustion characteristics using fish oil biodiesel. Experimental investigations on a single cylinder, constant speed, direct injection diesel engine were carried out under variable load conditions. The performance, emission and combustion characteristics such as brake thermal efficiency, hydrocarbon, exhaust gas temperature, oxides of nitrogen (NO_x), carbon monoxide, smoke, carbon dioxide, ignition delay, combustion delay and maximum rate of pressure rise were considered. Engine performance was measured using an exhaust gas analyser, smoke metre, piezoelectric pressure transducer and crank angle encoder for different fuel blends and engine load conditions. The obtained data were recorded for each experiment and associated data used to develop a multiple inputs and multiple outputs fuzzy logic model. The developed model produced idealised results with the correlation coefficients of 0.988–0.999 and root mean square error, and was found to be useful for predicting the engine performance characteristics with limited number of available data.     

如何做好建设工程安全监理工作之浅谈

结合工作经验,针对目前建设工程监理现状,就如何做好建设工程安全监理工作进行了论述,分别从七个方面作了说明,从而确保工程建设的安全性,推动建筑工程监理行业的健康发展。     

A Multiply Connected Belief Network approach for schedule risk analysis of metropolitan construction projects

Metropolitan construction projects may be distinguished from other types of projects due to their specific nature. Issues with regard to purchase of property obstacles, a lack of accurate layout drawings for some underground facilities and, therefore, following probable changes in designs make it vital to have specific studies on risk analysis of such engineering projects. However, conventional methods offered in literature of risk analysis fail to consider the interactional mechanisms of risks and their simultaneous occurrence. This paper exploits the Multiply Connected Belief Network approach in MATLAB environment to analyse the simultaneous occurrence of risk factors on schedule delay of a highway project. The method of inference is through Junction Tree Algorithm due to existence of multiply connections in the developed network of the project. The findings for schedule delay were tested in a different space using Monte Carlo simulation and had satisfactory results.     

上海复兴东路越江隧道联络通道施工过程的三维有限元与智能分析

在上海复兴东路越江隧道进行联络通道施工时,位于浦东的上层联络通道布置了一部分倾斜冻结管进行了冻结法施工.用倾斜冻结管进行联络通道冻结法施工,目前还找不到成熟的理论来计算其温度场和应力场,但温度场和应力场的精确计算对确保联络通道施工的安全性和经济性非常重要,基于此,用三维有限元方法对温度场进行了计算模拟,然后与现场测试结果进行了对比,对比结果表明,有限元计算的温度场有很好的精度.又采用自行开发的自适应神经网络专家系统软件对温度场进行了预测,预测结果令人满意.选取最合理的模型参数值通常是很困难却又很重要的,研究温度场对计算参数的敏感性对获得合理的计算参数非常重要,为此,讨论了温度场对计算参数和相关指标的敏感性.最后,用模糊控制器给出了施工预控制方案.研究结果对隧道工程施工技术和冻结法施工技术的发展很有助益.     

新时期建设工程质量风险管理模式的探讨

针对风险管理的重要性,指出要迅速有效地推行建设工程质量保险制度,必须突破现有的法律法规体系,建立新的管理模式,就两种风险管理模式的主要特点及优缺点作了论述,通过分析比较得出风险管理的最优模式.