Dynamic investigations on medieval masonry towers: vibration measurement and structural identification.

The vibration measurement and the structural identification of two Middle Age’s towers has been presented and analyzed. Compressive tests, flat jacket tests and environmental vibration measurement are used for the structural identification. Soil profile, semi-destructive test and “on site” recorded measurement, as well as preliminary historic and technical archive documentation of the monument have been collected and used in order to understand the dynamic behaviour of the towers. A critic evaluation of all this results and information have been cross linked, and an iterative analysis has been carried out calibrating and better refining the finite element model of the structure. The procedure adopts a minimization of the error function calculated between the dynamic behaviour of the numerical model and that one of the real structure monitored during environmental vibrations. The uncertainties related to the masonry body, considered as a homogeneous material even composed by different type of stones, has been widely discussed. The paper gives some satisfactory results in term of dynamic analysis of masonry bodies largely not homogeneous, as well as all the preliminary information for further reinforcing design activity.