Proceedings of the 57 Annual Conference of the Japan Society of Civil Engineers (25-27 September, 2002) Dynamic Features of End-cross Beam Reinforced Twin-girder Bridge

INTRODUCTION The lower ratio of dead load to live load than existing multi-girder bridges, wide girder spacing and simplified structural system of the twin-girder bridges can give rise to change of dynamic characteristics of the bridges. Wider girder spacing and changing of dynamic features will also effect on a vibration serviceability of the bridges. What is worse, according to running vehicles, a bump near an expansion joint will cause excessive high frequency vibration at an end-cross beam and deck slabs near the expansion joint . To prevent undesirable vibration at the end-cross beam of multi-girder bridges as well as enhancing the resistance of the expansion joint and the deck slabs at the beam end, countermeasures called as an end-cross beam replacement 2] and an endcross beam reinforcement 3], 4] have been devised and applied. In this study, the end-cross beam reinforcement is applied to prevent the undesirable vibration expected in the twin-girder bridge, and an analytical investigation about the reduction effect on traffic-induced vibration of the twin-girder bridge by reinforcing the end-cross beam is carried out as a preliminary study for the affirmation of the effectiveness. Moreover effects of the bump at the expansion joint and the end-cross beam reinforcing patterns on dynamic features of the twin-girder bridge are investigated.