Dynamic behavior of a Historic Tower in Bari

In this paper identification techniques are applied to the data obtained from the dynamic monitoring of the reinforced concrete tower of the Provincial Administration Building of Bari (Italy). The tower, about 60 m high, belongs to a complex monumental structure; it is placed on the waterfront with the principal façade in the northwest direction (the dominant wind direction) closed to a street often subjected to intensive traffic. The tower has been instrumented with 13 accelerometers fixed at different levels of the tower, and ambient vibrations, due to wind and traffic, have been recorded. The experimental set-up is illustrated and the modal parameters, identified both in the time and in the frequency domain, are described in detail. The major problems in the operational modal analysis (OMA) essentially concern the treatment of the data obtained from the experimental measures . In the present paper, these problems have been faced with several different experimental tests for comparison aims, in order to obtain the correct identified modal parameters. A good match between the modal parameters carried out by using three different methods, the classical EFDD and SSI-UPC methods and the new CC-SSI method, was reached for each of the ambient vibrations registered. Moreover the first 5 mode shapes were identified and opportunely outlined for evaluating the characteristics. The results of this research will be used in future studies for updating the finite element model of the tower.