In civil and mechanical engineering, the monitoring of structures is still a frequently investigated research topic. The basis of the present monitoring concept is the analysis of non-destructive measurements taken at regular time intervals to provide information about the current state of damage in a structure. The approach includes two steps: First, a data-driven stochastic subspace identification is applied to obtain a mathematical description of the system. Using a special state-space transformation, we transfer this result into physically meaningful system properties. Thereby the modal information can be separated into a part which describes the undamped system response and a second contribution which represents the influence of the damping. In the second step, we discretise the experimental setup by means of finite elements and apply an iterative finite element model updating algorithm to localise and to determine the damage. One important innovative aspect of the contribution lies in the updating of an entire damage evolution in order to estimate the lifetime of the structure. The experimental laboratory setup is based on a cantilever beam which is damaged locally and progressively with the help of a special device.