Impact-induced vibration effects on the real dynamic behaviour of cable-stayed bridges

Cable-stayed bridges (CSBs) are flexible and complex structures. Impact-induced vibrations may play an important role in the behaviours of the structural elements. Much effort has been devoted to clarifying the experimental static and dynamic responses of CSBs. However, experimental dynamic responses of the structural elements of CSBs under impact-induced vibrations have not been widely addressed in the literature. The focus of this paper is on the real experimental dynamic behaviours of cables, decks and pylons in CSBs under impact-induced vibration due to fully loaded trucks passing over a bump positioned on the deck centre. Tests were carried out on the new Kömürhan CSB under the passage of two 40 t trucks travelling at 30 km/h and passing over a timber bump of 50 mm thickness. The dynamic responses of the structural elements were recorded using load cells and two- and three-dimensional accelerometers. Forces, accelerations and frequencies of the main- and back-span cables and the acceleration responses of the deck and pylon, recorded with and without impact effects, were evaluated and compared. Significant impact-induced amplification ratios on the responses of the main- and back-span cables, deck and pylon were observed for the studied bridge.