Dynamic Behavior Comparison of Steel-Composite and Concrete High Speed Railway Bridges

The dynamic behavior of two steel bridges crossed by the Korean High Speed Train (KTX) has been investigated experimentally and the results are compared with the specification requirement and other typical prestressed concrete box girder bridge's responses. The investigated bridges are two 2-girder steel bridges, one of 1@40 m span length, and the other of 2@50 m span length, and a PSC Box girder bridge of 2@40 m span length. A set of experimental tests were performed during the operation of KTX, and a number of accelerometers, LVDTs and ring-type displacement transducers were utilized for measurement of three kinds of dynamic responses (acceleration, deflection, and end-rotation angle). Measured responses show that the vertical deflections and end-rotation angles of the three bridges all satisfy the spec. requirement with a large margin, but acceleration responses were also found to be very close to, or exceeded, the limit value. It was found that most of the excessive acceleration responses occurred when the passing speed of the train is close to the critical velocity which causes resonance. No noticeable differences of dynamic responses due to the different materials (steel or concrete) could be found within these experimental results.