Vehicle influence on road bridge superstructure damping

Abstract

   Wind loads lead to bridge oscillations. To verify aeroelastic stability of superstructures physical aerodynamic investigations are performed with vehicles taken into consideration. Usually oscillation amplitudes in this configuration are much bigger than without vehicles. At the same time, stiffness and damping of the vehicles are not modeled as that could decrease oscillation amplitudes.
   The main goal of this work is to determine vehicle influence on bridge superstructure damping. To solve the system of equations of motion from which vertical oscillations of vehicle – structure system were determined implicit Newmark method was implemented. Vehicle – structure system damping was assessed by logarithmic oscillations decrement, obtained from the results of free decay and forced resonance vibrations.
   Calculations were performed with different number of traffic lanes used by vehicles. Furthermore, suspension stiffness and damping also varied. As a result, it was obtained that for suspension with good damping characteristics vehicle – structure damping system was several times bigger than for superstructure without vehicles. With a satisfactory condition of the suspensions, the influence of vehicles can be estimated at 20 %.
   The obtained results can allow increasing the decrement of superstructure model in physical aerodynamic investigations with consideration of vehicles. However, it is necessary to carry out some research on determination of most frequently used vehicles’ suspensions.