COMPARISON BETWEEN DESIGN RULES FOR PTFE BRIDGE BEARINGS IN AASHTO AND EUROPEAN STANDARDS

The paper reviews the prescriptions given by the two worldwide most popular codes on bridge bearings, the North-American AASHTO LRFD Bridge Construction Specifications and the European standard EN 1337, for design and assessment of PTFE sliding bearings. The differences in materials and operations between the two continents are reflected in the codes. While EN 1337 is based on a large amount of research data, and specified design values are supported by experimental assessment, the approach of AASHTO LRFD Specifications is more empirical, and primarily based upon historic data and manufacturers’experience. In general provisions of the AASHTO code are more conservative as concern permissible loads and rated coefficients of friction, but consideration of the effect of wear and temperature is missing. Applicability of wear figures of EN 1337 to PTFE surfaces subjected to high velocities shall be investigated