Developpement de parapets prefabriques en betons renforces de fibres pour les ponts

In Canada, bridge parapets are almost exclusively built on site to ensure a good connection with the bridge deck. This construction technique is time consuming and delays the use of new and repaired bridge decks. Moreover, shrinkage of cast-in-place parapets is restrained by the bridge deck and leads frequently to early-age cracking. The combination of cracks and the severe environmental exposition of parapets (freeze-thaw and de-icing salts) can provoke early deterioration. An effective solution to the previous problems is the utilization of precast bridge parapets made with fibre reinforced concrete. Precast parapets are quickly installed on the deck with mechanical anchors and do not show shrinkage induced cracking as their deformations are free to occur before their installation. Besides, the presence of fibre in high performance concretes allows reducing parapets cross-section, steel reinforcement and crack opening under loads.;The second stage was to fabricate at real scale parapets (2 m long and 0.88 m high) for evaluating the mechanical performances with a various static and dynamic loadings in the laboratory. Those tests demonstrated that the proposed precast FRC parapets achieve adequately the criteria of the Canadien Highway Bridge Design Code (CSA-S6-06). The analysis of the global efficiency of parapets underlines that the FRC 50MPa-1% precast parapet is presently the optimal design.;This document presents new designs of precast parapets and the results of static and dynamic loadings. Finally, it concludes with recommendations on the use of precast bridge parapets.;The initial stage of this project consisted of proposing new designs of precast bridge parapets adapted to the utilization of three categories of fibre reinforced concretes (FRC 50MPa-1%, FRC 70MPa-1.5% and FRC 120MPa-4%) base on finite element calculations with computer software Atena 3D.