The assessment of seismic behaviour of existing buildings is a necessary and pressing activity within the national scene, due to the sizing practices used in the past, the state of conservation of structures and the unpredictability of natural phenomena.

The entry into force of Decree-Law 95/2019 together with Ordinance 302/2019 emphasised this necessity, making it mandatory to prepare a seismic vulnerability assessment report in most rehabilitation interventions.

This type of assessment is essential for determining the vulnerability of existing buildings and structures and consequently for defining the necessary measures for their strengthening. This is a process that should be carried out through the application of an integrated methodology which includes: the characterisation of the existing structure through inspection and diagnosis actions; the assessment of seismic response/safety under current conditions; the assessment of special requirements in relation to the class of importance of the building; and, finally, the assessment of the need for intervention and the development of seismic strengthening projects.