Research Article
Somayeh Ghorbani Noe
Abstract
As projects grow and develop and become more complex, new tools are needed to help manage projects. One of these tools is risk management, because in an unstable and uncertain environment, one can expect Out-of-schedule and unexpected events at any time. Experts' knowledge is often used to assess the ...
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As projects grow and develop and become more complex, new tools are needed to help manage projects. One of these tools is risk management, because in an unstable and uncertain environment, one can expect Out-of-schedule and unexpected events at any time. Experts' knowledge is often used to assess the risk of projects, but humans always use words and phrases in their conversations that have no clear boundaries. Fuzzy logic is used to deal with such ambiguous words and phrases. Fuzzy set theory is a method that has proven effective in managing uncertainties similar to those mentioned in construction projects. A fuzzy expert system is an expert or knowledge-based system that uses a set of fuzzy membership functions and rules to reason data instead of binary logic. For systems with high uncertainty where sufficient and accurate information is not available, the fuzzy approximation reasoning approach is proposed. Fuzzy system input can be inaccurate information and system processing is done using approximate reasoning. In this study, the risks in construction projects were investigated by obtaining the opinions of experts in the fields of clients, consultants and contractors. By providing steps, we have tried to identify risks, evaluate them, and control high-priority risks using fuzzy logic and expert systems.
Research Article
abolfazl yazdani
Abstract
Lack of government resources and severe need for infrastructure development facilities, governments need to attract the private sector in the country's infrastructure projects, BOT can be considered a reliable way to attract private capital, our country has also used this method in recent years. For ...
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Lack of government resources and severe need for infrastructure development facilities, governments need to attract the private sector in the country's infrastructure projects, BOT can be considered a reliable way to attract private capital, our country has also used this method in recent years. For all its benefits to the BOT system, there is plenty of experience with BOT projects around the world that has failed or at least failed to achieve its intended purpose; They warn us in choosing this method. The aim of this study was to investigate and rank the risks inside and outside the project in BOT projects using library studies and combining it with field surveys. The continuation of identified risks is analyzed and prioritized using expert opinion collection. For this purpose, a questionnaire was used and to analyze the results and data obtained from the field survey, SPSS24 software was used as the most powerful statistical analysis software and to deduce the results. From the field survey, Heider test was performed on the accuracy of the answers, the validity and reliability of the answers. In order to check the normality of the data, skewness coefficient and elongation coefficient, in order to optimize the variables, one-sample t-test, etc. were used.
Research Article
Roozbeh Aghamajidi; Rahim Hajibagheri
Abstract
Increasing study and research on the components of concrete structures has led to the availability of materials, the use of which in turn has been able to have a tremendous impact on concrete production. Concrete is undoubtedly the most important building material, the production and consumption of which ...
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Increasing study and research on the components of concrete structures has led to the availability of materials, the use of which in turn has been able to have a tremendous impact on concrete production. Concrete is undoubtedly the most important building material, the production and consumption of which is increasing day by day and it is used in almost all structures. The performance of cement as one of the main components of concrete products has always been considered and with the increasing development of Iran's cement industry in terms of quantity in the production of cement, cement quality control by examining physical and chemical properties is very important. In this study, we tried to investigate the factors affecting the strength of hydrated cement used in concrete structures in Shiraz and the results indicate a decrease in concrete strength due to increasing the ratio of water to cement and also C3S and C2S are the two main compounds causing cement strength are hydrated.
Research Article
Somayeh Ghorbani Noe
Abstract
Nowadays, there is risk in all aspects of life and construction projects are not excluded of this rule. Existence of risks and uncertainties in different stages of work is the main reason for the project's failure to achieve its predetermined goals. Project risk management is the science of identifying, ...
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Nowadays, there is risk in all aspects of life and construction projects are not excluded of this rule. Existence of risks and uncertainties in different stages of work is the main reason for the project's failure to achieve its predetermined goals. Project risk management is the science of identifying, analyzing, and responding to risk over the life of a project that is used to reduce or eliminate the likelihood or effects of adverse outcomes on project time, cost, and quality targets. The FMEA technique is one of the methods of determining the value of risk that not only identifies the errors and defects that are hidden and obvious in the system and process, but also searches to reduce or eliminate them by taking the correct preventive measures. To analyze the risks in construction projects, we are faced with uncertainties such as ambiguity, and fuzzy theory provides the necessary mathematical tools to deal with vague and ambiguous data. Accordingly, in this study, a model consisting of seven basic steps based on the combination of FMEA technique and fuzzy logic was proposed. The risks in construction projects were identified with the help of previous studies and researches and the effective parameters on the risks were quantified by experts. By calculating the risk priority number, the risks were ranked. In addition, a method for calculating and mapping the level of risks was introduced, which identifies not only critical risks but also all high-risk components of the project risk Breakdown structure. Also, in order to reduce or eliminate the negative consequences of high-priority risks, corrective measures were investigated in the research.
Review Article
Hooshang Piri
Abstract
Around the world, delays are a common and common issue for the employer, consultant or contractor in any project [13]. The causes for delays in large railway projects are very complex given the characteristics of the whole project area [19]. Delays in projects impose a lot of costs on the employer and ...
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Around the world, delays are a common and common issue for the employer, consultant or contractor in any project [13]. The causes for delays in large railway projects are very complex given the characteristics of the whole project area [19]. Delays in projects impose a lot of costs on the employer and the contractor, so identifying the causes of delays and ranking them can be a great help for the success of other projects [1]. In this article, various researches in the field of factors affecting the incidence Delays in rail and transportation construction projects have been investigated, and key factors in delays in construction projects have been identified from four sources: employer, contractor, consultant, and others. In most studies, the method of collecting field information was a structured questionnaire and interviews with a survey approach. To find English articles ̒Google Scholar̓ and Persian articles were used from ̒civilica̓ database. In this study, in addition to domestic articles on the causes of delays in the country's railway and construction projects, foreign articles on the causes and delays railway projects in Malaysia, Ethiopia, Saudi Arabia, China and Korea were used. Finally, it was found that 100% of railway construction projects have suffered from time delays and the most important cause of delays in projects has been the lack of funding and timely payment of funds to the contractor and lack of proper planning.
