Study on vibration transmission characteristics of high-speed railway simply-supported box-girders based on in-situ hammer excitation test

Based on an in-situ hammer excitation test, the vibration transmission characteristics of a 32-m-long simply-supported prestressed concrete box-girder in high-speed railway are investigated. A track-bridge coupled system model is established based on the finite element method to calculate the mobility of track slab, sub-base slab, and box-girder top slab in the frequency range of 1Hz to 1000Hz. The model is validated by comparing with the test results. The vibration transmission characteristics of the box-girder are studied and the influences of top slab thickness, middle web addition, stiffness and damping of used fastener system are discussed. Additionally, the vibration transmission characteristics of the box-girder under practical wheel-rail impact force are analyzed. Results show that the top slab mobility is the largest in the one-third octave center frequency range of 20Hz to 200Hz, and the flange slab mobility takes second place. While, the web slab and bottom slab mobilities are relatively small. The top slab vibration decays rapidly within a distance of L/8 (L denotes the box-girder span) from the exciting point, but decays slowly beyond that range. Increasing top slab thickness, adding a middle web, and increasing fastener damping are beneficial to the vibration and noise reductions. The vibration velocity of box-girder slabs under practical wheel-rail impact force is relatively high in the one-third octave center frequency range of 40Hz to 80Hz, in which induces significant structure-borne noise. © 2016, Editorial Office of China Civil Engineering Journal. All right reserved.