Emmanuel Ferrier’s research while affiliated with Claude Bernard University Lyon 1 and other places

Over the past decade, the textile-reinforced concrete (TRC) composite was gradually used to replace the fibre-reinforced polymer in the strengthening or repairing of existing reinforced-concrete structures, thanks to many criteria of sustainable development. The reinforcement ratio of textiles within TRC composites emerges as a crucial factor significantly impacting their reinforcement effectiveness, altering the material’s mechanical behaviour and properties. This study presents both experimental and numerical findings concerning the tensile behaviour of carbon TRC composites, exploring reinforcement ratios ranging from 0.5 to 1.5%. As experimental results, the carbon TRC specimens exhibited a strain-hardening behaviour with the cracking phase. The ultimate strength improved by 95 and 146% compared to that of non-reinforced specimens, respectively, with the reinforcement ratio of 0.92 and 1.32%. As numerical results, the model reached the strain-hardening curve with three distinct phases when the reinforcement ratio was higher than a critical value (0.7%). The effect of reinforcement ratio ranging from 0.5 to 1.5% on the mechanical behaviour and properties of carbon TRC was also highlighted and analysed.

This paper presents the outcomes of a comprehensive experimental investigation aimed at characterizing the in-plane shear strength of Unreinforced Masonry (URM) wallettes subjected to diagonal compression. The study focuses on the strengthening of these wallettes using precast Ultra-High Performance Concrete (UHPC) diagonal strips, externally bonded onto the wall substrates through high-strength epoxy mortar. Twenty-three wallettes, each measuring 1000 mm × 1000 mm × 70 mm, were meticulously constructed and subjected to in-plane diagonal compression. Among these, eighteen wallettes underwent strengthening utilizing various configurations of UHPC, with a key emphasis on variables such as UHPC strip width and thickness, substrate nature, and corner confinement with enlarged UHPC rectangular plates. Findings from the experimental program highlighted the significant influence of UHPC retrofit parameters on the wallettes performance. Notably, corner confinement emerged as an effective strategy against premature toe crushing failure, enhancing the wallettes ability to withstand higher in-plane compressive loads. While UHPC strip width exhibited moderate impact, UHPC strip thickness emerged as a dominant factor. Increasing strip width from 100 to 250 mm yielded an approximate 8% shear strength improvement, whereas doubling strip thickness from 10 to 20 mm led to a substantial 27% enhancement. Notably, enhanced strip width demonstrated pronounced benefits in terms of ductility and energy dissipation capacity. Excessive UHPC retrofit thickness induced brittle failure despite escalating shear strength. Conversely, thinner UHPC retrofits achieved a favorable balance between strength, ductility, and energy dissipation. Wallettes retrofitted with 5 mm UHPC exhibited an impressive 2.36-fold shear strength increase compared to reference walls, while those with 10 mm and 20 mm UHPC retrofits experienced 2.14 and 2.78-fold improvements, respectively. Furthermore, the manner of UHPC application significantly influenced the strengthening system's behaviour. For identical strengthening layouts, the direct bonding of UHPC onto masonry substrates resulted in a 25% increase in shear strength compared to UHPC bonding onto plaster overlays.

Mechanical connections of rebars are widely used and demonstrated high effectiveness in reinforced concrete structural elements, but the differences in the performances of different connection methods in reinforced concrete beams from the perspective of adhesion, bending, and load transfer are rarely documented. In addition, existing rebar connections are large and may lead to local cracking because of their size. In this study, we investigated the use of compact mechanical couplers by pull-out tests and bending tests of full-scale reinforced concrete beams. For pull-out tests, the influence of the couplers position in concrete was studied. Different rebar configurations were tested for beams: continuous, with a covering, or connected with compact mechanical couplers. The nonlinear behaviour of beams was analysed under monotonic and cyclic load conditions. The overall behaviour of beams is discussed in terms of load–displacement curves and concrete cracking distribution. To study the local behaviour, digital image correlation was set up, allowing to monitor strain distribution and crack opening. Experimental results show no significant impact of the compact couplers on the global or local behaviour of reinforced concrete beams compared to the beams using continuous rebars: failure load, overall stiffness, and crack distribution are similar, in the uncertainty range of tests. The regulatory calculation of crack openings and spacing fits the experimental results for most of the studied cases.

In 2018, the French Association for Civil Engineering (AFGC) formed a dedicated working group to focus on the application of Fiber-Reinforced Polymer (FRP) bars for the internal reinforcement of concrete structures. The primary objective was to establish French recommendations by conducting a comprehensive review of existing standards and knowledge in the field. A technical report gathering those recommendations (in French) was released in 2021 and is currently undergoing translation into English. This report comprises six chapters covering various aspects, including the characterization of FRP reinforcing bars (rebars), their durability and temperature behaviors, as well as design recommendations for ultimate and serviceability limit states, encompassing flexure, shear, punching shear, fatigue, and pile reinforcement. Additionally, several case studies are presented in the Appendix.

A hybrid use of glass fiber-reinforced polymer (GFRP) reinforcement and fiber-reinforced concrete (FRC) could be a viable option for producing durable precast concrete tunnel lining (PCTL) segments. There is, however, a gap in the literature regarding the behavior of GFRP-reinforced FRC PCTL segments with typical amounts of reinforcement. This paper presents results obtained from both experimental and analytical studies on the behavior of GFRP-reinforced FRC PCTL segments under bending load (flexure). Four full-scale tunnel segment specimens were constructed and tested monotonically under three-point bending load. The influence of concrete type, reinforcement ratio, and tie configurations on the cracking behavior, deflection behavior, failure mechanism, load-carrying capacity, strain behavior, and deformability was evaluated. There is a limited analytical procedure available to predict the shear and flexural capacities of GFRP-reinforced FRC PCTL segments. Therefore, an analytical investigation was carried out in order to propose and evaluate different methods for predicting the flexural and shear capacities of such elements. The results indicate that the use of FRC significantly improved the cracking behavior and failure mechanism while also increasing the load-carrying capacity and deformability by 12% and 71%, respectively. Increasing the reinforcement ratio by 86% enhanced the post-cracking stiffness and peak load by 92% and 31%, respectively, while reducing the service-load crack width by 57%. According to the analytical investigation, the introduced direct method based on the stress–strain behavior of the FRC and the proposed simplified method based on ACI 440.1R-15 could predict the flexural capacity of GFRP-reinforced FRC PCTL segments with high accuracy. Furthermore, the method proposed to modify CAN/CSA S806-12, R2017 to consider the contribution of fibers in shear transferring mechanism yielded rational conservative values for the shear capacity of GFRP-reinforced FRC PCTL segments.

Timber-concrete composite (TCC) structures consist of thin concrete slabs connected by stud or bonding to glulam beams. They emerged as a valuable system with lightweight elements characterised by high strength and stiffness. However, the structural efficiency of real-scale TCC floors with an adhesive-based connection systems requires further investigation to confirm the promising results of small-scale experimental studies. To contribute to this investigation, this study conducts real-scale experiments on five timber-concrete composite floor specimens that are linearly supported at two edges. The flexural behaviour of the system is assessed using a four-point bending test, and its strength and displacement capacity are also tested. The study also provides insights on the strain profile and relative displacement of the system's cross sections. The experimental results indicate that the composite structure has adequate mechanical behaviour that is characterised by a linear response up to failure, without relative displacement at the concrete-timber interface surface. The study confirms the potential of TCC floors as prefabricated construction elements, demonstrating that the system complies with standard performance requirements.