Evaluation of Modal Parameters of a Full Scaled Prestressed Concrete Beams for Railway Bridges

초록

The estimation of exact dynamic behavior is very important in railway bridges which can undergo resonance state from repetitive moving axle forces with uniform intervals. Therefore, it is very important to evaluate the modal parameters of PSC girders that have been newly designed before doing moving load analyses. In this paper, a full scale incrementally prestressed concrete girder of 25 meters long as a test specimen was fabricated and modal testing on it at every prestressing stage was carried out to evaluate the modal parameters, including the natural frequency and the modal damping ratio. Young’s modulus was also obtained from global stiffness of the test specimen. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied, in order to obtain precise frequency response functions, and the modal parameters were evaluated with various construction stages. With the application of reliable properties from the modal experiments, an estimation of dynamic performances of PSC girder railway bridges can be carried out with various parametric studies of the dynamic behavior while undergoing the passage of a moving train.