Design of a Specific Bituminous Surfacing for the World's Highest Orthotropic Steel Deck Bridge

This paper presents a rational approach for the performance-based design of bituminous wearing surfacings on orthogonally anisotropic steel bridges. The behavior of bituminous surfacings on steel orthotropic decks under heavy truck traffic and environmental conditions is highly complex. Both the geometry of the structure and the high flexibility of metallic plates make the deformations and stresses severe in steel bridge surfacings. In particular, the repeated loading makes the fatigue strength an important parameter for the design of such bituminous wearing courses. In addition, these specific surfacings must have durability over the expected temperature range, and they must be resistant to thermal cracking at low temperatures and to rutting at high temperatures. The technical studies that were conducted in parallel with the construction of the Millau Viaduct (France)–-the world's highest bridge–-have provided in particular the opportunity for progress in the development of appropriate laboratory testing equipment and of an original polymer-modified surfacing. A comprehensive research program, including both a large laboratory testing campaign and a finite element parametric study, was performed to develop a useful tool for the design of plate surfacings.