| 摘要 |
PROBLEM TO BE SOLVED: To obtain an effective control effect in a simple structure by providing a bridge control device formed by an elastic material disposed on the back of a girder or a floor plate, and a constraint mass body. SOLUTION: A bridge 1 is formed by a main girder 2 and a floor plate provided thereon. The back of the floor plate 3 is provided with a control device (a composite control device) 6 for a bridge formed by an elastic material 4 such as soft urethane foam or the like and a constraint mass body 5 such as a steel plate or the like. The composite control device 6 is so constituted that a control object frequency is a bending primary natural frequency of the bridge, and the amount of elastic material 4 used and the amount of steel plate 5 as the constraint mass body used are controlled to resonate with the frequency, thereby exhibiting a passive control function. The bridge control device may be formed only by a vibration damping material provided on the back of the floor plate 3, or a constrain mass body may be provided on the lower surface. Thus, even in a comparatively simple structure, vibration produced when a large vehicle passes between bridge supports or an expansible joint part of the bridge can be reduced, an effective control is obtained, and low frequency sound of the same band as that of vibration can be reduced.
|
