It is essential to investigate on dynamic behaviors for development of an advanced railroad bridge with long-span and low-depth. In this study, the 2-girder railroad bridge of 30m length, 3.1m width and 2.48m depth was fabricated to analyze on dynamic characteristics and behaviors of PSC Railroad Bridge with Unified Prestressing System of PS Strands and PS Bars. Experimental tests were carried out using an impact hammer, vibration exciter, and dynamic actuator based on the conditions with and without rail track.
As a result, the first natural frequency of the system with rail track was decreased 7.8% in the case of using the impact hammer compared with the results without rail track, but it was increased 3.3% by in the case of using the vibration exciter. Considering the size of specimen and the level of excitation force, it is found that the results of vibration exciter test are more reliable than those of the impact hammer test. In addition, it was considered that the effect of stiffness increasement was not measured in the tests with rail track using the impact hammer due to the insufficient dynamic displacement. Therefore, the first natural frequency was increased because of the rail track construction and it is because the addition of stiffness primarily affects on the first natural frequency rather than the mass supplement.
According to the evaluation of damping ratio tests using the logarithmic decrement method, no noticeable damping ratio changes due to the rail track construction could be observed from the both experiments using a vibration exciter and dynamic actuator.