Numerical simulation of the five-point bending test designed to study bituminous wearing courses on orthotropic steel bridge

The structural role of the wearing courses on orthotropic steel deck bridges is usually not estimated during the design process. Both geometry of the structure and very high flexibility of steel plates induce severe stress and strain fields in the steel bridge surfacing. In this paper, we quantify the influence of a bituminous mix surfacing on the steel plate response when considering the French Five-Point Bending Fatigue Test. Mechanical behavior of bituminous mixes is very complex. It includes a great thermal sensitivity. Moreover in the small strain domain (for strain amplitudes below about 10(-4)) the behavior can be considered as linear. Therefore, the theory of linear viscoelasticity can be applied. After introducing the French five-point bending fatigue test used at the research center of EIFFAGE Travaux Publics company, in parallel to the construction of the Millau Viaduct (France) -the highest bridge in the world-, a numerical parametric study using the Finite Element Method (FEM) is presented. The specimens are made of a 12-mm-thick steel plate, a 3-mm-thick sealing sheet and a 60-mm-thick bituminous mix. Different wearing course behaviors are considered introducing temperature and viscous effects. This behavior is modeled using the linear part of the general thermo-viscoplastic model A << DBNA >> (Di Benedetto and Neifar), recently developed at ENTPE laboratory and briefly described in this paper. An important observation is that the rigidity of the intermediate bituminous sealing sheet as well as the wearing course behavior seems to have a great influence on the orthotropic multilayer specimen complex behavior.