A Study On Optimizing The Construction Project Schedule Time Under Uncertainty Duration

With the economic development, project management is becoming increasingly important in social development. project Management Institute edited the Preparation of project management knowledge, and The project management is divided into nine knowledge areas: project management; project scope management; project time management; project cost management; project quality management; project human resources management; project communication management; project risk management; Project Procurement Management. project time management, cost management and quality management are the core areas of project management and are important aspects of project management. Time and cost are closely linked with each other. And constraints on the time and cost. Project time Optimization is a very important aspect, of great significance in practice.Most of the existing studies on the work of when the calculation time does not meet the planned time .how to compressedproject duration, make the compressed schedule will meet the schedule requirements , Few studies have study the optimization of time when the cost lest. the latter applied may has more widely use in engineering practice .Base on the development of the network plans to expand the scope of the project time optimization, in order to better meet the needs of the practice.The existing researchs on the time optimization are mostly in the network of working relationship and process duration are determined in the context, And according to time and cost of continuous or discrete relationship, the proboem has been solved by linear programming, integer programming or genetic algorithm approach. However, the uncertainty of the external environment, making the the duration of work is also uncertain. Under the conditions of the PERT network. project time optimization better reflect the objective real facts, more research value, and the study has attracted the attention of abroad scholars .When study the time optimization under the conditions of the PERT network . through the introduction of project risks and process to solve the problem of work duration uncertainty effectively in PERT network. Reflects on integration of the project duration, cost and risk optimization.Under the assumption of Working relationship and the continuous process are determined and based on the network conditions, the duration of each work is a fixed value, However, in engineering practice ,because of the various processes carried out by many external factors, using a fixed value to indicate the duration of the work is difficult to reflect the true situation accurately, This study basis on this consideration, that the duration of process is uncertainty. Therefore, this paper describes the practical issues in the PERT network in order to reflect more nature of engineering practice realistically, that is under study in the PERT network study the time optimization .This article assumes that in the condition of the duration and cost of work has continuous function ,that study the time optimization problem.in the CPM network the logic process are determine, but the duration is uncertain, so the completion of the project time is uncertain. it has certain risks to complete in a schedule. that people are concerned on completion risk, people always want the completion of the project time and cost very little, while the project completion and cost overrun risk is minimal.The purpose of project time optimization in the PERT network is the optimization of time, cost and duration and cost risk . in certain risk conditions, ask for the corresponding period when the cost minimum.Based on the assumption that the direct costs and the work duration is the linear relationship, we study the described methods of work duration. Analysis of the original probability and statistics method to describe the duration of the process and its shortcomings. when we plan the network. As the uncertain external environment subject to the project .leading to a network work process duration is uncertain, it is not effective to clearly defined for us, in this paper .the duration of work reflected the strong uncertainty of the ambiguity .Therefore, the uncertainty of work duration is also show ambiguity.On this basis, we work on the construction project time optimization model. Using fuzzy linear programming method to solve this problem. In considering the various factors that affecting the level of risk conditions, we select the appropriate level of risk, optimizing the value of work time, used to guide the practice.