No abstract

As heavy trucks pass over highway bridges, bridge vibration occurs and generates infrasound. General trucks in Japan with rear leaf suspension have whole body vibration (suspension spring vibration) frequencies of about 3 Hz. Also, the frequencies of the wheel vibration (tire spring vibration) are about 10-20 Hz. The continuous steel highway bridges with middle span length have vibration modes with the same phase in each span at the frequencies of about 3 Hz and also have those with the secondary mode shape at the frequencies of about 10-20 Hz. Truck vibrations and bridge vibrations are closely related. In this work, vibration tests are conducted using a heavy test truck for two cases of infrasound complaints in order to investigate the relation between the continuous steel bridge vibration modes generated by the vibration of moving heavy trucks and its infrasound characteristics. As a result of the examination, two types of bridge vibration modes are caused by the vibrations of a moving heavy truck. Moreover, the bending vibration modes with the same phase in each span have the most powerful infrasound pressure, since each span vibrates with the same phase. Two countermeasures, including viscoelastic damper at the end of the girders and extended deck method, are proposed to reduce the amplitude of bridge vibration and its infrasound.

This paper presents the result of the study of the influence to the traffic vibration on the ground.Vibration on the ground, it is not clear how to exchange vibration characteristics with roughness near the expansion joint. Then we had vibration test and roughness measurement in girder of highway bridge, and we examined the relation between roughness and vibration.As the result, it is clear that vibration caused by roughness near the expansion joint effects ground vibration, and a factor in ground vibration.

Vibration caused by running vehicles on a highway bridge is spread to the superstructure, substructures and ground. The ground vibrates both in horizontal and vertical direction. When vehicles load at the tip of the cross beam in the T-shaped pier, rocking vibration of the pier occurs. Its ground vibration in transverse direction is the biggest. In the two-box girders bridge, which bearings are installed at the tip of the cross beam of the T-shaped pier, the ground vibration has greatly occurred due to the rocking vibration of the pier. Two measures to mitigate the vibration are proposed in this study. The evaluation the change of the vibration characteristics and effects of the measures to mitigate the vibration are also discussed in the study.