Structural behaviour of surfacings on steel orthotropic decks and considerations for practical design

Surfacings on steel orthotropic decks act compositely with the steel deck plate and must be regarded as an integral part of the structural deck system. Surfacing materials are generally visco-elastic to plastic and behave elastically only at low temperatures. Elastic moduli of most surfacings strongly depend on temperature. In semi-plastic condition flexural strain distribution through the surfacing thickness becomes non-linear. With a soft bonding layer, shear slip occurs at the interface. Surfacings contribute substantially to deck rigidity and are subject to considerable stresses due to local bending of the steel deck plate. Locations and causes of critical deck plate stresses affecting surfacing performance are discussed. Characteristic properties of the two basic surfacing categories, the bituminous and the polymer materials, are presented with examples of their applications on orthotropic decks. It is suggested that satisfactory performance of surfacings should be achieved by more stringent limitations of the local deck flexibility.