Developing a system dynamics model to study the relationship between human resource motivation and time productivity of construction projects

Recent studies have clearly demonstrated this fact motivation is directly linked to increased productivity in human resources. Therefore paying attention to employees' motivational factors and their needs is important to ensuring productivity and performance improvement of organizational projects. In a few researches the motivation of human resources and the effect of different factors on the change of motivation and its effect on the time productivity of construction projects have received less attention. Therefore, the aim of this article is to investigate the effect of change of motivation and the factors affecting it on the time efficiency of construction projects with the approach of system dynamics. For this purpose, after identifying the effective parameters on the motivation of human resources, from sampling data using survey studies with questionnaires and interviews, library sources and collecting information. the qualitative modeling and effect loops between parameters were performed with the Vensim software package. Also, the relationships between parameters were determined with the quantitative modeling. In the following, the model was implemented to the real project by defining different scenarios based on changing the effective parameters on the motivation of manpower and the time efficiency of office-commercial building project. The results showed that if there is a 50% increase in manpower motivation in the project, the correct rate of work is increased up to 3 times and the project takes 690 days and 30 days. The results also show that a 50% reduction in salary increases the delay in completing the project by about one year and a 20% delay in payment of salaries leads to an increase in project completion of up to 4 months and an increase in the ratio parameter. Wages will be reduced by up to 2 times 5 months after the completion of the project.