Emmanuel Denarié

The elastic limit tensile stress of UHPFRC is governed by contributions of the cementitious matrix and the fibrous skeleton. This paper finds that fiber orientation has significant influence on the matrix tensile strength of UHPFRC, while this is not considered in current estimation of elastic limit tensile stress. An original model relating fiber orientation to the elastic limit tensile stress is proposed. Uniaxial tensile tests have been conducted on ten dumbbell-shaped specimens, whose local fiber volume and orientation are determined using a magnetic probe before testing. Based on the results of local fiber distribution, the influence of fiber orientation on the elastic limit tensile stress is discussed, showing that the proposed model estimates well the elastic limit tensile stress of UHPFRC.

(PE)-UHPFRC, a novel strain hardening ultra high-performance fiber reinforced concrete (UHPFRC) with low clinker content, using Ultra-High Molecular Weight Polyethylene (UHMW-PE) fibers, was developed for structural applications of rehabilitation. A comprehensive life cycle assessment (LCA) was carried out to study the environmental impact of interventions on an existing bridge using PE-UHPFRC compared with conventional UHPFRC and post-tensioned reinforced concrete methods in three categories of global warming potential (GWP), cumulative energy demand (CED), and ecological scarcity (UBP). The results showed 55% and 29% decreases in the environmental impact of the PE-UHPFRC compared with reinforced concrete and conventional UHPFRC methods, respectively, which highlighted the effectiveness of this material for the rehabilitation/strengthening of structures from the viewpoint of environmental impact.

Offshore lighthouses are a remarkable historical heritage often over 100 years old. The management of their ageing is a challenge and requires a thorough understanding of their structural response under wave loading. With this aim in view, the dynamic response of the ‘La Jument’ lighthouse in the French Iroise Sea was characterizedin situ, with accelerometers, under the action of a breaking wave, during a winter storm in January 2018. Detailed exploitation of the measurement data complemented by photographic documentation of the same wave event helped determine eigenfrequencies and damping coefficients of the structure as well as the likely orientation of the wave and the position of its crest with respect to the lighthouse tower. The results of these analyses were put into perspective with those of literature and more specifically from three-dimensional finite element modelling of the structural response of the lighthouse under the action effects of breaking waves.This article is part of the theme issue ‘Environmental loading of heritage structures’.

Strain Hardening Ultra High Performance Fiber Reinforced Concretes (SH-UHPFRC) have a high elastic limit (around 10 MPa) and high tensile strength (upto 20 MPa) and exhibit significant strain hardening (1 to 4 %_°) under tensile loads. These appealing features make them extremely effective materials for strengthening and improving the durability of existing structures. However, their cast on site application induces significant eigenstresses due to restraint conditions. In this paper, the effects of various restraint conditions on the tensile viscous response of SH-UHPFRC was determined experimentally using a Temperature Stress Testing Machine and was modelled. Tests were done at partial and full restraint conditions to study the eigenstresses development. The ageing linear viscoelastic response of the material was modeled using an ageing generalized Maxwell model, fitted on the experimental data of eigenstresses. The influence of the scatter of free shrinkage measurements on the model prediction was studied through a sensitivity analysis.