Use of UHPFRC overlay to reduce stresses in orthotropic steel decks

• Orthotropic bridge deck stress reduction due to an UHPFRC overlay was investigated.
• Numerical and experimental programs were carried out on a realistic sample.
• Different types of overlay and thicknesses were evaluated and compared.
• Results obtained confirm the beneficial effects of UHPFRC overlay.
• 60% strain reduction at the bottom of the welded joint on deck plate side.

This paper aims at presenting the results of experimental and numerical investigation programs assessing the stress reduction in orthotropic steel bridge decks associated with ultra high performance fiber reinforced concrete (UHPFRC) topping layer. This R&D project was aimed at evaluating the effectiveness of the UHPFRC overlay, as an alternative to conventional bituminous concrete, to reduce the stress distribution and thereby improve the fatigue resistance of the complex deck plate. Loading tests were carried out on realistic samples of orthotropic deck equipped or not with a reference bituminous concrete or a new UHPFRC topping. The deflection, and strain and stress values on the top and the bottom of the orthotropic deck plate and more particularly at the weld joint between longitudinal stiffeners (troughs) and the deck plate were measured. A 3-D shell element model has been developed using a finite element code in order to obtain the stresses in details for the most representation and critical locations. The global and local behaviors have been analyzed in order to understand and to evaluate the beneficial effects of UHPFRC topping layer under static condition. The results obtained in terms of stress reduction factor demonstrate the beneficial effects for fatigue verification.