Vibration of hangers on a tied-arch bridge due to vehicles

Based on Component Mode Synthesis method, the vehicle-bridge interaction problem of a concrete-filled steel tubular tied-arch bridge was analyzed. The mathematical model assumed a finite element representation of the bridge together with beam, shell, and link elements. And the vehicle simulation employed a three dimensional linear vehicle model with seven independent degrees of freedom. A well-known power spectral density of road pavement profiles defined the deck surface roughness for Perfect, Good and Poor roads respectively. In virtue of a home-code program, the dynamic interaction between the bridge and vehicle model was simulated. Thus the dynamic responses of the hangers were obtained to study the actions on the hangers such as the local impact effects from vehicles, the plane stress variation, and the amplification factors. Under the passing vehicles the hangers vibrate with frequencies that are closely to their fundamental ones. The calculated local DAFs varies between 1.05 and 1.30 for the hangers, which are higher than the global ones and those specified by some codes. The shorter hangers are more susceptible to fatigue problem than the longer ones.