Claes Kullberg

Modelling of Pot Bearings – A Preliminary Study

Previous research indicates that roller and pot bearings may give rise to considerable non-linear effects in certain bridges. These effects appear as variations in natural frequency, mode shape and modal damping ratio, depending on the amplitude of vibration. At small amplitudes of vibration, it seems reasonable to assume that the rolling or sliding mechanism is inactive, thus yielding a stiffer structure and no additional dissipation of energy due to friction. At slightly larger amplitudes of vibration, although still remaining small with respect to geometrical non-linearity, the rolling or sliding mechanism activates, whereby the corresponding constraints are relieved. At the same time, because of the rolling or sliding friction, a certain amount of energy dissipates to the surroundings. In order to improve our understanding of these mechanisms and their practical implications, a preliminary experimental study has been performed with the aim of developing a simple model of these mechanisms, which can be included in theoretical models of bridges and other structures. In this paper, we give a short description of the outcome of our laboratory tests and the status of our model development process.