Optimization of lift operation time by a linear mathematical model in high-rise construction projects with considering non-demand fines

Timely delivery of materials and equipment to the floors of a high-rise construction project is one of the main challenges for project managers. To solve this challenge, tools such as lifts and cranes are used to transport materials vertically. For the reasons explained in the text of the article, the lift is a more suitable option for the vertical movement of materials in high-rise buildings. The way the lift moves between the floors of the building and the amount of material moved by the lift in each round directly affect the completion time of the project. Therefore, providing an optimal schedule for vertical transportation of materials in a high-rise project can lead to proper use of time and prevent delays in the project. In this paper, a mathematical model with the priority of activity in the day shift and also meeting the maximum amount of demand in two consecutive shifts, to minimize the time of lifting activity is presented.The proposed model tries to meet the demand of the classes as much as possible, and if the demand is so high that it is not possible to meet the demand during two consecutive shifts, considering the fine, it gives the best way to move the lift. Finally, the proposed method is validated on a real data sample related to a high-rise project. The proposed model, in addition to examining the actual sample compared to the models introduced in similar studies, provides an optimal material handling schedule for each work shift.