Failure Analysis of Pot Bearings in a Curved Viaduct

Abstract

This paper presents a failure analysis of pot-type bearings on the West 8th Avenue viaduct in Denver, Colorado, and aims at determining the causes of guide bar fracture, polytetrafluoroethylene (PTFE) peeling, and steel–steel grind. All the failure modes of the pot-type bearings resulted from the thermal response of this structure. Two finite-element models were applied in this study. One model was developed using SAP 2000 to examine the thermal effect, including transverse and longitudinal movement and vertical pressure. The other model was developed using ANSYS software and emphasized contact analysis based on stress and displacement contour plots. The purpose was to demonstrate how the components of the bearing structure interact when subjected to the movement and stress transferred from the superstructure. The results indicated that when the upper steel plate of the bearing was subjected to transverse and longitudinal movement, the excessive movement caused the guide bar to hit the steel pot. The lateral slippage of the two components occurred simultaneously, leading to the generation of steel–steel grind of the two components. Extremely large-edge contact stresses arose from the eccentrical loading on the PTFE, resulting in PTFE wear and peeling in the long term. Because the steel pot resisted the intermediate section of the guide bar, the guide bar was laterally bent. Initial cracking was induced, and low cycle fatigue loading accelerated the crack expansion in a radial plane until the guide bar fractured.