عنوان مقاله [English]
Construction projects risks have a systemic nature that imposes difficulties to determine their consequences. Moreover, it is impossible to determine the consequences of risks on the project cost and time simultaneously using traditional risk analysis approaches taking account of the interactions existed between the project cost and time.
This research aims to present a new approach for the risk analysis in construction projects that resolves the major shortcomings of the traditional risk analysis techniques by integrating system dynamics simulation scheme and
fuzzy logic. The proposed approach can determine the risks consequences quantitatively. For this purpose, first a qualitative model of the project execution process is constructed using cause and effect feedback loops. The
relationships existed between different variables are then determined and a quantitative model of the project is built. The presented project model can simulate the project objectives in terms of cost and time simultaneously
since the interdependencies existed between project cost and time are accounted by the governing cause and effect feedback loops. In order to determine the risk consequences, the qualitative model of different risks are similarly constructed. Then, the relationships existed between different factors are determined and the quantitative model of different risks are built. The magnitude of risks is determined using a fuzzy logic based "risk magnitude perdition system" which implements a Mamdani style fuzzy inference mechanism.
Finally, the project model is simulated in two different cases, i.e., considering the risks and disregarding the risks. The consequences of different risk are determined by the comparison of simulated results achieved from the
project model. The proposed approach determine the negative impacts of risks on the project cost and time simultaneously by simulation of the project execution process and considering the systemic nature of risks.
In order to evaluate the capabilities of the proposed model, it is implemented in a sample water pipeline project. The consequences of "construction errors risk" are simulated on the project and time using the proposed integrated fuzzy system dynamics approach. It is shown that the proposed method has the ability to determine the risk consequences at different confidence levels. It is believed that the proposed risk analysis technique provides a new tool by which the risk consequences on the project cost and time could be simulated