Resource-constrained construction project scheduling model for profit maximization considering cash flow

Regarding project scheduling problems, resource-constrained issue is generally considered essential for contractors as a means. Researchers have thus devoted considerable efforts to investigating this issue over the past decade. Furthermore, since adequate cash flow management benefits cost control and assists profit acquisition for contractors, numerous techniques have recently been developed for project scheduling in situations involving cash flow. However, most of these studies simplified resource utilization, and assumed that cash out flows are directly related to activities without considering resource usage. Fundamentally, resources incur activities' costs, project cash flow, which conforms to resource utilization. It is thus regarded as a main issue in this study. This study establishes a resource-constrained project scheduling model based on constraint programming, whose solution can be found by using combinatorial optimization algorithms. The proposed model integrates the issues involving resource-constrained problems and cash flow, and maximizes net project cash flow to optimize project profit from the perspective of contractors. Model validation and two scenarios, including multi-resource, resource combination selection, and various constraints such as resource limit, are performed to demonstrate the model capability and applications. Contractors thus can evaluate appropriate project schedules under associated constraints, and arrange activities and resources to maximize project profit.