Research on Construction Schedule Optimization of Assembly Building Based on NSGA-II

Abstract

Considering multiple possible scenarios in the process of project construction, the prefabricated project scheduling problem is studied in combination with the theory of multi-mode resource-constrained project scheduling problem. Multi-objective multi-mode resource-constrained project scheduling model with time/robustness trad-offs was constructed. Next, the adjusted non-dominated genetic algorithm (NSGA-II) was designed to solve the model. Finally, the proposed model and algorithm were implicated to a real project, in order that research achievement can guide managers to make decisions and invest resources scientifically and reasonably.

Scheduling Optimization of Prefabricated Construction Projects by Genetic Algorithm

“…Figure 10 demonstrates that in the event that the delivery of the prefabricated components required in activity 9 is delayed by 2 days, the maximum completion time of the project is delayed by 24 days. Activities 10,11,12,13,20,21,22,23, and 24 all delayed the start time compared with the schedule in Figure 8. Especially for activity 20, even if all its predecessors have been executed on the 13th day, due to the constraints of renewable resources, activity 20 has to wait until the 16th day to start work.…”

“…Generally, on-site construction arrangements are the leading factor, which governs the production and transportation arrangements of factory prefabricated components [89]. Wang and Lian's research was based on the analysis on the assumption that the prefabricated components arrived on time [23]. However, delays in the delivery of prefabricated components are not rare in the construction process of prefabricated construction projects, which is also an important reason for the deviation of the project schedule [90].…”

“…However, some uncertainties are observed in the simulation results, and further research is needed in using the model to guide engineering practice. Wang and Lian [23] established a multiobjective and multimode resource constrained project scheduling model with time/robustness considering various possible situations in the process of assembly project construction. The adjusted nondominated GA is designed to solve the model.…”

“…For verifying the practicability of the proposed algorithm in solving practical engineering problems, this section applies the designed GA to the project scheduling problem of actual engineering cases. The selected case is adapted from the study of Wang and Lian, and it is used to analyze the trade-off between the duration and the robustness of a multimode prefabricated construction project [23]. The project is a new prefabricated industrial plant in Shaanxi Province, China.…”

“…This study has developed a prefabricated construction project scheduling optimization model that is more intuitive and easy to solve to make up for the failure to fully consider the impact of the supply of prefabricated components on the scheduling model and the limitations of simulation modeling in the previous research [16,23]. The model considers the priority and resource occupation constraints of project activities and transforms the constraints of production and transportation of prefabricated components into supply time constraints into the optimization model.…”