الفهرس 
Chapter One : IntroductionOnly 14 pages are availabe for public view
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Abstract
The construction industry is considered to be one of the most dynamic and risky sectors in all countries. Many construction projects do not attain their desired goals due to the presence of risks and uncertainties intrinsic in the projects. The mechanical portion of a construction project often represents a significant percentage of the total cost of the whole project. The track record of the mechanical portion of a construction project is very poor in terms of risk management, resulting in the failure of many projects to meet time schedules, budget targets, and sometimes even the scope of work. For these reasons, and because of the increased importance of relevant mechanical systems in buildings, the research efforts in the area of relevant mechanical systems in the construction management need to be expanded to cover risk analysis. The mechanism of present research implementation consists of three phases. The details about each phase will be presented in the following paragraph.
The first phase objectives are to identify the main activities associated with HVAC system installation in construction projects, as well as the risk factors that affect them. Other objectives include conducting an analysis and assessment of the effects of these risk factors on time and cost objectives. Multi-stage field surveys are used in this study. The major risk sources are qualified in terms of their severity, probability of occurrences, and impacts on project time and cost. Three activities associated with HVAC system installation are identified: (a) air distribution duct work, (b) chilled water distribution pipe work, and (c) HVAC equipment installation. Fifty-five risk factors that affect each specific activity and that are common to all activities are also identified and categorized into four groups. Two agreement analysis tests and a full statistical analysis were conducted. A high degree of agreement between all partners was obtained. The time and cost percentages of the three activities were determined. A detailed discussion and analysis indicated that approximately 50% of the key risks belonged to common risks that affected all activities, while the most important risky activity was chilled water distribution pipe work. Furthermore, the analysis emphasized that the number of risk factors increased as the expected duration of the activity increased; however, this relationship did not exist in the case of cost. Ultimately, the obtained results indicate that the expected time and cost overruns caused by the effects of risk factors on HVAC system delivery are approximately 10–20% and 5–10%, respectively.
The objectives of the second phase are to develop a new qualitative and quantitative risk analysis model that can be employed for construction projects. The proposed model, which is based on a fuzzy logic tool, consists of two modules for assessing risk factors that affect the main construction activities and compute the expected cost overruns and time delays that are associated with these risks. Using numerous logical rules, the model applies the probability of occurrences and impacts of the risks on the cost and time of the main activities. The model is verified through application to HVAC system activities in two actual projects, which serve as case studies. Two different methods are proposed and applied to quantify the cost overruns and time delays. The first method is based on determining the cost overruns and time delay values for each activity according to their weight in the system. Triple premise rules are proposed and applied in the second method. The results from the second method are more accurate compared with the first method based on actual data. The results also, demonstrated that the proposed model can be used to quantify the expected cost overrun and time delays in construction project activities.
Third phase introduces a new strategy to assist contractors in evaluating and selecting suitable projects. The developed new strategy, which is based on identifying multi criteria that control the construction projects as well as developing and using a model that supports a decision based on the Analytic Hierarchy Process (AHP). Furthermore, a fuzzy risk analysis model is proposed to be used in analyzing and quantifying some of the identified criteria and help contractor to select projects of minimal risk. Market conditions, financial resources, project conditions, time delays and cost overruns are five recognized criteria along with other subsidiary factors affecting them. The influence and importance of the first three criteria are identified through a field survey, while, the time delays and cost overruns criteria are quantified through the risk analysis model. The new strategy is applied on a real case study which consists of two HVAC systems in the construction projects. The obtained results from the investigated case study support the selection of project II by 55.5%, while the selection of project I is only supported by 44.5%. This strategy is valid to be applied on other case studies in different countries based on modifying alternative projects, criteria and execution activities.