PROBLEM TO BE SOLVED: To provide a noise reduction structure of a viaduct capable of reducing the noise of structures from the viaduct.
SOLUTION: This noise reduction structure damps the vibration energy of a floor slab E1 since a vibration damping layer 2 suppresses a floor slab lower surface E3 because the upper surface of the damping layer 2 is fitted to the floor slab lower surface E3. Though the soft elastic material of the damping layer 2 shearingly deforms due to the vibration of the floor slab E1, the vibration of the floor slab lower surface E3 is damped by covering a part of the vibration energy into a heat energy by an internal loss due to the viscous resistance of a soft viscoelastic material. Further, since a constraint layer 3 is stacked on the damping layer 2, the deformation of the damping layer 2 is retrained by the restraint layer 3. Since the shearing deformation of the damping layer 2 is amplified and the internal loss of the damping layer 2 is amplified, the vibration damping capability of the damping layer 2 can be largely increased. By stacking damping layers 2 and the restraint layers 3 with low rigidness are stacked, spring-dash pot-mass structure is formed as an physical system, and the vibration is also cut off.