Rogério Bairrão - Senior Research Officer, C۳ES - LNEC, Lisbon, Portugal
ricardo teixeira duarte - Principal Research Officer, C۳ES - LNEC, Lisbon, Portugal
carlos trancoso vaz - Auxiliar Research Officer, C۳ES - LNEC, Lisbon, Portugal
alfredo campos-costa - Auxiliar Research Officer, C۳ES - LNEC, Lisbon, Portugal

This paper presents the methodology that has been developed by the National Laboratory for Civil Engineering (LNEC) for the earthquake design of important structures. The advantage of this methodology is that it is fully supported by quantitative models that allow the consideration of the main sources of uncertainty relevant to earthquake design. The methodology is based on: i) a seismic generation zones model that describes the seismicity and allows the computation of the probability distribution of the site earthquake intensity parameters; ii) representation of risk consistent hazard scenarios by non-stationary stochastic models of earthquake vibrations; iii) nonlinear analysis of structures for hazard scenarios corresponding to different probabilities of occurrence, to obtain the vulnerability functions; iv) use of vulnerability functions and probabilistic models of structural resistance to evaluate the probability of failure; v) use of shaking table testing to validate the basic assumptions of analysis.