Research On Optimization Of Time/Cost Trade Off Of Repetitive Construction Projects

The most basic scheduling goal of time-cost tradeoff problem is:the shortest project duration under the condition that total resources has been given (project budget problems), or the minimum cost in the conditions that a given project period (the bottom period problems). For repetitive scheduling projects, the goal of project scheduling can also boils down to this two kinds. Time-cost tradeoff problem is generally multi-mode selection, each procedure has a variety of implementation methods to choose, different methods corresponding to different time and cost. The process of the optimization of time-cost tradeoff is the new combination of the models, this kind of problem is Np-hard questions. Therefore this paper uses intelligent optimization algorithm to realize the optimization process of time-cost tradeoff problem. But in the project scheduling, the controlling path of the project is the key of determining total duration, and there are different degree of shortcomings and insufficiency in the determination before, therefore, the first thing is redefined the controlling path, made sure the controlling path method, make the determination process of controlling path more accurate, more in line with the actual requirements. And then describing the conditions of continuity constraint, including that distinguish the continuous process from intermittent, resources continuous and discrete use constraint conditions. Analysising the process and methods of the period under the condition that the preference constraint relation in the activities, and the continuity restraint of resource, a variety of execution modes.To realize the optimization of repeatability scheduling problem of time and cost, the paper describes the time and cost model of RSM. Time model mainly aimed at calculating the time of activity, time constraints. The cost model includes material costs, labor costs, equipment cost and total expenses, etc. According to actual, the time/cost tradeoff is divided into two models:calculating the minimum cost identified time, calculating the minimum period identified cost. And in the process of computation, this paper uses genetic algorithm to solve the problem that there are large of the constraint relations between activities. Genetic algorithm not only faster, and we can solve a multi-objective question. The model for repeatability project scheduling problem was to provide the executor of the effective time-cost tradeoff optimization method, and finally there is an example of time calculation for a bridge, and by using the genetic algorithm.