Operational modal testing of an arch type steel highway bridge using SSI technique

The paper determines the dynamic characteristics of an arch type steel highway bridge applying ambient vibration testing. A modern steel highway bridge which has arch type structural system with 216m total length and located in the Ayvacik county of Samsun, Turkey is selected as an application. Because of the fact that the bridge connects the villages which are separated with Suat Ugurlu Dam Lake, it has a major logistical importance for this region. The construction of the bridge completed in 2009 and opened the traffic. The experimental meas-urements are carried out by ambient vibration tests under traffic loads. Vibration data are gath-ered from the bridge deck. Measurement time, frequency span and effective mode number are determined considering similar studies in the literature and initial finite element analysis re-sults. Stochastic Subspace Identification technique (SSI) in the time domain are used for the output only modal identification and dynamic characteristics such as natural frequencies, mode shapes and damping ratios are determined, experimentally.