Vibration and noise mitigation analysis of railway steel-concrete composite bridge using constrained layer damping

Abstract

The constrained layer damping can achieve the significant reduction of the vibration and noise from the treated structure in a wide frequency range by means of dissipating the vibration energy owing to the damping layer’s shear deformation. Based on the modal strain energy method, train-track-bridge coupled vibration and statistical energy analysis, a theoretical model for the calculation of the train-induced vibration and noise from the railway bridge with constrained layer damping was presented. The vibration and noise from a (32 +40+32) m steel-concrete composite bridge treated by constrained layer damping was computed and tested. Analysis results indicate that: the computed vibration and noise from the (32 +40+32) m steel-concrete composite bridge with constrained layer damping agrees well with the experimental results. After webs of the bridge were treated by 328.23 m2 constrained layer damping, the vibration acceleration effectively diminished in the whole analysis frequency band, and the acceleration level of the web and the bottom flange are reduced by 8.1 and 4.4 dB respectively. The sound pressure level is reduced by 4.2 dB (A) and 4.3 dB (A) at S1 and S2 successively. There are optimal values in terms of the shear modulus and the thickness of damping layer. If the thickness of the constraining layer is too large, the ability reducing the low-frequency noise gradually degenerates.