A hybrid model for the prediction of low–frequency noise emanating from a concrete box-girder railway bridge

Abstract

Concrete box-girder bridges are widely used on high-speed railway and urban rail transit lines; however, the low-frequency noise generated by these systems has not been intensively studied. The prediction of bridge-radiated noise is a complicated procedure and can require prohibitively long computational times. This paper presents a hybrid finite element and statistical energy analysis (hybrid FE–SEA) procedure for the prediction of bridge-radiated noise, with the aim of reducing computational time while still guaranteeing accuracy. A simplified train–bridge coupling model is first introduced and solved in the frequency range 20–200 Hz; the wheel–rail interaction force is calculated and taken as the vibration excitation. The hybrid FE–SEA model is then constructed, in which the rail and ballastless track are modeled as the SEA subsystems and the bridge girder components as the FE subsystems. The bridge-radiated noise is finally estimated by considering each vibrating component of the bridge as a flat plate. The procedure is applied to predict the vibration and noise emanating from a simply supported concrete box-girder bridge with a standard span of 32 m, and the computed results are compared with those obtained from in-situ measurements. The numerical results are in good agreement with measured data, and comparisons between computed and measured results reveal that the noise radiation from adjacent spans needs to be considered at a perpendicular distance of 25 m from the track’s centerline. Furthermore, the vibration transmission mechanism and the acoustic contribution performance are investigated, based on the validated numerical model. The results show that the vibrational energy of the top slab has the highest value; however, the vibration of the flange cannot be ignored. Therefore, the top slab and the flange, which may respectively account for 50% and 25% of the overall noise contribution at far-field points, should be given priority when formulating noise-mitigation measures.