Pressure Distribution in Sliding Interface of Spherical Bridge Bearing

Relevant literature indicates that the critical parameters relating to load transfer in the curved, sliding, compression-only, polytetra-fluoroethylene (PTFE)-metal interface of a spherical bearing under an external applied horizontal load are the ratio of the horizontal load to the vertical load and the ratio of the radius of curvature to the plan diameter of the interfacing spherical surfaces. An experimental program measuring the stress-displacement relationship of confined PTFE discs under uniaxial and eccentric compressive loadings is described, and a bilinear stress-displacement relationship is proposed. This stress-displacement relationship is incorporated into a displacement model to predict the stress distribution in the PTFE in the curved interface, and results from the model are compared with those from a finite-element model. The displacement model is used to develop design charts for spherical bearings under combined vertical and horizontal loads.