AN OPTIMIZATION MODEL FOR PRECAST PROJECT PLANNING USING GROUP CONCEPTS
Journal of the Operations Research Society of Japan
Construction projects adopting precast pieces are feasible to reduce project uncertainties over components which are produced in factories, stored in factories or external sites, and transported with trucks to satisfy installation demand. In order to create project plans, planners should arrange available resources and select appropriate ways to produce, store, and transport components. This study adopts several group ideas to organize an overall precast project. Based on these group concepts,
... se group concepts, an optimization model and a recursive procedure are proposed. Appropriate molds and zones can be determined in the recursive procedure, and the project plan can be created through the optimized project cost. An example experiment is demonstrated to explain the feasibility of the proposed model and group concepts. Lecture Review Precast related studies can be classified to two types: techniques and planning. Precast techniques can mainly refer to the annual International Symposium on Automation and Robotics in Construction (ISARC) conference. Novel techniques or machines are continually innovated and developed. These techniques or machines not only provide chances to enhance ability of precast works, but change behavior in producing, storing, and transporting precast components. Therefore, precast planning involves changeable work environment according to technique issues. Only a few studies on precast planning have been investigated. Planning issues of the production stage have been studied for years. Chan has conducted several studies in production planning. In order to cater to different degrees of component standardization, Chan and Hu  proposed two models: (1) the comprehensive method utilizes resources regularly to produce components; (2) the specialized method considers low component standardization. Furthermore, Chan and Hu  proposed a Constraint Programming based optimization model to compare regular rules of component production. Components and molds were grouped into component types and mold types. Chan and Zeng  and Chan and Zeng  proposed a coordinated production scheduling and rescheduling model respectively. Chan and Lu  adopted simulation to build scenarios of viaduct production for analysis. Both supply-demand matching and high productivity were under consideration. Others, such as Leu and Hwang  have proposed a GA-based scheduling model considering the resource-constrained environment. The importance of manpower, cranes, steam curing capacity, and storage space of reinforcement cages are issues. Investigations of storage-transportation planning have seldom been made. One of the reasons is the huge components. Containerization has a similar issue that definitely should be explored. Vis and Koster  discussed the process of transporting containers from ships to a terminal. Avriel et al.  proposed a mathematical model to reduce the number of times a container is moved. However, various shapes of components are reasons why few investigations are made. Sadiq et al.  proposed a cluster-analysis base model to classify objects into several groups, then allocating groups to store objects. Shih et al.  proposed component zoning, such that components are grouped into zones to create storagetransportation plans. Furthermore, inventory and transportation are related to time-base and quantity-base issues as Cetinkaya et al.  mentioned. The Acheson and Glover Group  developed a precast storage system. Storing precast components with few secondary movements and well-located components was considered. Based on responsibility of precast factory, production, storage, and transportation stages are essential to concern. To handle changeable work environment caused by novel techniques, precast plans must contain flexibility to keep them practical. Adopting group concepts provides a solution to precast project planning. Framework Explanation The quantity of components for a construction precast project can be hundreds or even thousands. Grouping components is necessary in precast projects. In practice, components are standardized into groups for at least three advantages: (1) components can be unified, and work can be simplified; (2) high production efficiency can be achieved, and resources can be utilized repeatedly; (3) components can be reciprocal substitutes. As a natural assumption of precast projects, a high degree of component standardization is required, or the precast method may be unsuitable. Before planning a project from the perspective of the precast factory, component infor-Copyright c by ORSJ. Unauthorized reproduction of this article is prohibited.