In recent years, intensive research and development have been done in the area of construction project risk management. Indeed, an efficient risk management is mandatory to project success. However, implementing such a management is complex because of the diversity and the dynamic nature of the risk. Moreover, each of the project stakeholders has his/her own risks, his/her own vision and his/her own action on the project and on risks. In this paper, we propose an agent-based model called SMACC to assess the impact of risks on the project. This model allows to test different risk mitigation strategies to measure their impact on the project. An application on a real project is also proposed to demonstrate the operability and the value of the proposed approach.