This lecture introduces the risk-based approach in seismic assessment, focusing on the Swiss Standard SIA 269/8. The instructor explains how existing structures can be evaluated for seismic safety, considering individual and collective risks. Various topics such as compliance factors, seismic design specifications, and risk acceptance criteria are covered, emphasizing the importance of cost-effective interventions. The lecture also discusses the evolution of seismic standards over the years and the principles behind the assessment strategy, particularly beneficial for regions with low to medium seismicity.