برنامه نویسی خطی چند منظوره برای زمانبندی در پروژه های ساختمانی
Abstract
1- Introduction
2- Literature review
3- The proposed model
4- Example of implementation
5- Conclusions, limitations, and recommendations for future research
References
Abstract
Repetitiveness in project's activities has gained an important role in the construction industry. Multiple linear scheduling methods have been proposed in order to fully take advantage of the spatial and temporal information these type of project can provide to practitioners. Besides the advances in the optimization models in these fields, to the extent of the authors knowledge, there is still pending a complete and flexible mathematical linear programming formulation that allow practitioners to easily and jointly solve the Resource allocation, Resource-Constrained Project Scheduling and Time-Cost Tradeoff problem, taking into account as many scheduling properties, benefits and challenges that linear scheduling of repetitive activities imply. This paper shows a complete guide and computational experimentation, of a novel mathematical model that can be easily used by practitioners to optimize construction schedules considering to the largest extent the time and space conditions repetitive projects offer. Particularly, it contributes to the repetitive activities scheduling body of knowledge by successfully implementing a robust linear programing optimization model in a real construction project, while considering as much linear scheduling characteristics as possible. It proves that relationships in the sub-activity level, continuity conditions, multiple modes of execution, controlled acceleration routines and execution mode shifts, and multiple crews can be easily and jointly integrated to a linear optimization model by adding simple linear restrictions to the model.
Introduction
The improvement of the scheduling techniques has always been a very important field of study in construction not only at the scholar level, but at industrial level. Researchers working collaboratively with industry practitioners have developed numerous mechanisms in order to deliver projects in a more efficient way. Specifically, time and resource consumption efficiency are one of the most important challenges that schedulers must overcome when a new project is conceived [1–3]. As the nature of the construction project differ, traditional scheduling methods has been extensively criticized, forcing specialized scheduling tools to emerge [4–7]. Extensive literature research has demonstrated that these traditional time-driven techniques do not display spatial and resource consumption information that allows practitioners to build schedules based on spatial resource consumption continuity and distance constraints [5,8–11]. Particularly, these methods fail to incorporate resource continuity and distance constraints, while offering poor or none information about crew execution times and location [11]. Additionally, the uninterrupted placement of resources in construction units is not a problem addressed by them, nor by its resource-oriented extensions [5]. To overcome this limitation, authors have proposed modification to networks techniques that can handle continuous and non-continuous connection of similar sub activities by using FS0 and maxFS0 relationships. In this line Hajdu [12,13], proposes PtP (point-to-point) and maxFS relationships to overcome precedence diagram method impossibility to simultaneously include location and time lags, non-linear activities and activity overlapping, assuming that activities are non-interruptable, besides OR and bi-directional relationships to deal with multimode execution modes and sub-activities. Despite all advances, all the previously mentioned limitations make traditional methods and techniques unsuitable for scheduling and controlling activities in which work is repeated in unit by unit throughout the length of the project.