ABSTRACT
ABSTRACT: The identification of the dynamic characteristics of civil structures, such as bridges are usually performed by means of forced vibration testing or ambient vibration testing. In the first method the structure is excited by shakers and it is also possible to record free vibrations subsequently an imposed displacement. With ambient vibration testing, the response of structures to actions such as wind, traffic, or seismic micro-tremors, is considered. Better results can be obtained when the ambient unknown action is a broad band signal, which guaranties the excitation of a wide range of frequency components.
