Department of Civil Engineering
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Browsing Department of Civil Engineering by Author "Abdulsattar, Abdulrahman M."
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Item A META-HEURISTIC FOR THE DISCRETE TIME-COST-QUALITY TRADE-OFF PROBLEM WITH GENERALIZED PRECEDENCE RELATIONSHIPS(2022-01-14) Abdulsattar, Abdulrahman M.; Aminbakhsh, SamanBuilding projects can certainly be considered as one of the most crucial elements that contributes greatly to economic growth of a nation. They facilitate developments in other industries too by providing appropriate working spaces and the means for mobilization of resources (e.g., office building, hospitals, schools, highways). Through unique public or private bids, the governments and stakeholders aim to achieve reasonable prices for such projects with minimum possible makespans and the best quality. Evidently, weighing the available offers and coming up with an optimal decision can pose challenges for the decision-makers. In this regard, generation of a tool that helps decision-makers strike a proper balance among the conflicting project objectives (i.e., time, cost, and quality) is imperative. To this end, this study proposes a method which assists in selection of the best compromise choices among the options available for each of the project activities. In addition to time and cost, the proposed method is designed to bring the quality aspect into the equation as well. To quantify the quality, a value referring to the weighted importance and performance of each activity is used. The proposed method is based on a slightly modified Genetic Algorithm (GA) that incorporates the domination concept for selection of the best solutions out of the potential candidates. The GA-based method is capable of handling unlimited number of precedence relationships for each activity and above all, it is able to capture and unravel any type of logical relationship. This very feature significantly improves the practical relevance of this research as parallelization of activities is a common practice in real-life projects. Planners by benefitting from the various types of relationships (i.e., Start-to-Start, Start-to-Finish, Finish-to-Start, and Finish-to Finish) and the concept of lag time frequently introduce parallelization into the network. Overlapped activities, in turn, help reduce the unwanted idle times and speed up the project significantly. In order to demonstrate the application and to evaluate the effectiveness of the proposed model, it is used for solution of three different Time-Cost-Quality (TCQ) tradeoff problems, two of which are generated within the context of this thesis. The practiced instances include a small benchmark TCQ problem with 18 activities taken from the literature in addition to more complex 29- and 63-activity TCQ problems produced herein based on existing 29- and 63-activity time-cost tradeoff problems, respectively. The obtained results reveal both the effectiveness of the proposed model and the possibility to be used by the planners amidst making arduous decisions.