CONDITION MONITORING OF BEARINGS USED IN MRT VIADUCT

Abstract

To achieve significant saving and timely replacement of the pot-bearings used in the MRT viaduct, a condition monitoring technique is introduced to assess the current condition of the bearings and predict the deterioration of the bearings. Acceleration and displacement measurements have been carried out to determine the most suitable parameters for condition monitoring. It is found that the relative displacement is the better choice. The patterns of the measurement records are distinctive and correspond clearly to the passing of the wheels over the bearings. A model is derived to represent the bearing-supported elevated viaduct with continuous tracks. The computed relative displacements of bearings during a passage of a train are in excellent agreement with measured deflection using eddy probes. The computed results show the bearing’s relative displacement is more affected by the change in bearing stiffness than changes in other physical parameters, such as system damping, ballast stiffness, train velocity and passenger load. The analysis shows that the ballast stiffness has very little influence on the peak-to-peak end displacements of the viaduct. A 30% change in passenger load causes a 11 % change in the end displacements of the viaduct. However, as the elastomeric material ages, an increase of 50% of the stiffness is expected and this in turn causes a decrease of 35% of the end displacements. This decrease is clearly detectable and discernible over the change due to the variation in passenger load. Furthermore, the peak-to-peak end displacements could indicate if either or both bearings have deteriorated. Thus, it shows that condition monitoring using the end displacements is viable.