**10. Conclusions**

This structural performance of old stone-masonry bridges is studied following a methodology that utilizes a large number of high fidelity *in situ* measurements in order to identify their dynamic characteristics (eigen-frequencies, eigen-modes and damping ratio) and corresponding numerical predictions from relatively simple or more complex numerical simulations. The validity of these numerical simulations was ascertained by comparing the measured *in situ* dynamic response with the one predicted numerically. This methodology was extended by applying such 'realistic' numerical simulations to predict the performance of specific old stonemasonry bridge structures (e.g. Konitsa Bridge) when subjected to dead load combined with seismic actions. A series of numerical dynamic analyses, both simplified (linear) and complex (non-linear), were made. In these analyses, actual earthquake excitation recorded in the proximity of Konitsa Bridge and relevant seismic code design seismic spectra were employed as well as earthquake records representing near-field (impulsive-type) or far-field seismic events. Seismic actions specified in these ways were used to investigate the damage potential of such stone-masonry bridges. It is believed that it is of great research interest to be able to apply this methodology together with measurements from a long-term monitoring and maintenance programme as a means of safeguarding the structural integrity of these precious cultural heritage structures. Finally, recommendations for intervention works should include clauses providing for preparatory actions of measurements and analyses similar to the methodology presented here. The same methodology can be applied to address flooding, which is also one of the main causes of structural damage for stone-masonry bridges that require special attention and is the subject of a separate study. Apart from the hydrodynamic loads that a stone-masonry bridge is subjected to from a flooded current, one of the main sources of distress that may lead to partial or total collapse is the deformability of the foundation. Finally, the integrity of the stone masonry in various parts of such old stone-masonry bridges is an additional maintenance issue of considerable importance. The following represent additional conclusive remarks:

