Structurae

A concrete filled steel tube arch bridge, Shitanshi Bridge, vibrated significantly after it opened to traffic. The purpose of the study presented here is to investigate the cause of such a significant vibration. First, a brief description of the bridge is given. Then, analytical theory is presented. The bridge free and forced vibration characteristics, including the accelerations of some key elements are investigated with both single and multiple trucks traveling over a rough deck at different vehicle speeds. Then, the stiffness effects of the deck and the arch ribs are studied. Analytical results show that insufficient deck stiffness was a main factor causing the severe vibration. Based on the analytical results, two stronger longitudinal beams were added to the bridge during a recent retrofit. As a result, bridge vibration due to the dynamic loading of moving vehicles is greatly reduced to an acceptable level. The research results are applicable to arch bridge design and rehabilitation.