DYNAMIC TEST OF A STEEL PLATE GIRDER RAILROAD BRIDGE WITH A RAIL JOINT

초록

This study investigates the effects of rail joints on the dynamic behavior of railroad bridges through a dynamic experiment. The subject bridge is a typical steel plate girder railroad bridge. A bridge is 53.4m long, and consists of 4 simply supported spans (4@12.10m). Rail joints are positioned in the 3rd span. It is 1.8m away from the starting point of the 3rd span. The regular service train applied the dynamic loading. A test train is composed of one diesel locomotive and 7 passenger carriages, which is commonly running on the existing railroad lines in Korea. The range of measured speed is from 19.1 to 124.0km/hr. Accelerometers are installed at the bottom flange of center of 3rd span to acquire bridge response caused by rail joint. In order to comparison, another accelerometer is installed at the same position of 1st span which has not rail joint. From measured results, Peak vale (PV), root mean square (RMS) and dynamic amplification factor (DAF) value analysis are performed to compare the instantaneous maximum and mean amplitude of acceleration at each span. The result shows a significant increase in the acceleration of the span with joints. Also DAF is from 0.22 to 1.92 for the measured speed zone. The result also shows that rail joints on a bridge produces impact effect. Thus, it increases the dynamic response of the bridge and deteriorates ride comfort.