Physical infrastructure like transportation, potable water, and electric power are the backbone of modern societies. Therefore, ensuring their uninterrupted performance in the face of uncertain operating conditions and future hazards is essential to economic security and social well-being. However, the consequences of past disasters have shown that infrastructure are vulnerable to multiple hazards. The scarcity of resources and the ever-growing demands on these systems call for resilient solutions that reduce the societal impact of hazards. This section focuses on some fundamental aspects mostly related to modeling, including 1) modeling of hazards relevant to physical infrastructure and the impact of climate change, 2) prediction of damage and loss of functionality of physical infrastructure, 3) post-disaster recovery modeling, 4) modeling of interdependencies among physical, social, and economic systems, 5) validation of models and predictions using historical data, 6) definition of relevant metrics of impact and resilience, 7) resolution and scale issues, 8) quantification and propagation of uncertainties, and 8) optimization of mitigation and recovery strategies.