Characterization of the tensile response of strain hardening UHPFRC - Chillon viaducts

The tensile response (strength and deformability) of strain hardening UHPFRC needs to be characterized by adequate test and analysis methods. Inverse analysis methods that do not appropriately take into consideration the influence of the UHPFRC softening behavior on its pre-peak response under bending significantly overestimate the UHPFRC strain hardening domain. Further, the determination of the elastic limit from objective methods remains a challenge. An original simple inverse analysis method has been developed which provides new objective criteria for the determination of: (1) the elastic limit, and (2) the strain hardening response of UHPFRC in the relevant pre-peak domain under bending. The paper reports on the major results achieved in this context, with the background and application of these new methods to the characterization of the tensile response of the UHPFRC used for the reinforcement of the Chillon Viaducts (Switzerland) in 2015.