Extend time - cost trade off model with Weighted Fuzzy Goal Additive Programming

AVIt is usually necessary to increase the resources of activities to for crashing project activities in a project, so project manager usually are engaged with this kind of problems. In order to reach this goal in project management, time-cost trade-off techniques are employed. While the principles of CPM method is based on certain activity duration time, and the fact that in a real project environment uncertainty is inevitable and the duration of critical path activities may change due to uncertainties, and consequently change the predicted project finish time. So in this study we use fuzzy theory to deal with this problem. In most of previous studies, researchers assumed one of the time or cost parameters as a fuzzy variable, but in this study we assume both time and costs as fuzzy variables. We cannot set a single path as critical path in a fuzzy project. In order to deal with this difficulty in time-cost tradeoff problem, we assigned a criticality weight for each activity in project network and put them in trade-off problem process. However, in most studies it is common to decrease the project duration time just by enhancing recourses, while by crashing activities the probability of risk rises in some activities. In this article we also minimize the risks caused by crashing project in a multi-objective time-cost trade off problem. It is also usual that researchers evaluate their multi-objective problem with similar objective weights, while it could not be acceptable and in our study we deploy a suitable methodology to solve multi-objective problems by regarding different importance weights.