| Construction project is a multi-target system in which emphasizing and highlighting a certain target singly and absolutely can not ensure the overall objective of the project would have been successfully achieved. Besides, as the implementation of construction project is a more subjective process, therefore, it is difficult to find the optimal combination of system goals (that is least investment, fastest progress, best quality, least influence to the environment). At this time, it is most important to comprehensively optimize the various objectives of the project.Firstly, this paper studies the basic theory of project objective optimization, such as the connotation of each project objective, the concept of quality and environment in this article, etc. In addition, this paper gives comprehensive discussion of the relationship among these project objectives -- Project Duration, Cost, Quality and Environment, and also analyzes the relationship between every two goals; then gives quantitative relationship between the various objectives. Secondly, this paper studies utility theory and multi-attribute utility function theory, pointing that the value of utility function represents the utility or integrated utility that various properties produce. The determination of attribute weight is one of the key points of this article. This paper analyzes the characteristics of several commonly used methods to determine attribute weight, finally uses Analytical Hierarehy Medel (AHM) to improve the model in order to strike the attribute weights and detailedly lists the calculation steps. On this basis, this paper takes the highest overall efficiency generated by project objectives as a guide, considers the quality and environmental objectives in the optimization process, then establishes the integrated optimization model of Project Duration--Cost--Quality--Environment by using the multi-attribute utility function theory. Once again, this paper analyzes the basic contents and solving steps of Particle Swarm Optimization (PSO) algorithm which is the solving method of the integrated optimization model, compares its characteristics with Genetic Algorithm, the author thinks that it is more appropriate to use the PSO algorithm solve the model. Finally, verifies the feasibility of the integrated optimization idea by an example, and briefly explains the optimization results and gives the application suggestions. |
