Chemisage de ponts

Rehabilitation and Strengthening of Bridge Piers with Ultra-High Performance Fibre-Reinforced Concrete Materials.

The maintenance of the large aging infrastructure in Wallonia and across the developed world poses serious technical, environmental, and economic challenges. This research project is envisioned as part of a long-term pursuit to provide solutions to these challenges by using a new generation of materials – ultra-high performance fibre-reinforced concretes (UHPFRC). In particular, the focus of the project is the rehabilitation and strengthening of corroded bridge piers by using UHPFRC layers on the surface of the pier. The main objectives are to confirm the technological feasibility of this method, and to develop a rational model for evaluating the shear resistance of piers strengthened with UHPFRC. To achieve these objectives, the project will include an experimental study combined with numerical and analytical modelling of retrofitted bridge piers.

The experimental part of the project will consist of the construction and loading to failure of two large wall-type piers with and without UHPFRC layers. Detailed measurements of deformations and forces will be used to understand the shear behaviour of piers and the effect of the UHPFRC layers. The results from the tests will also be used to validate a numerical model for the analysis of UHPFRC. This model will be developed by modifying a smeared rotating crack model for fibre reinforced concrete implemented in a finite element (FE) formulation. Both the experimental results and FE simulations will be used to develop a rational mechanical model for the shear behaviour of UHPFRC-strengthened piers by extending a three-parameter kinematic theory (3PKT) for reinforced concrete piers. As the 3PKT is based on first principles, it is expected to provide the basis for models of other important structural members such as deep beams, coupling beams, and pile caps. The ultimate goal is these models to be implemented in future design codes in order to facilitate the use of UHPFRC for the retrofit of critical infrastructure.

Goals of the research

The maintenance of the large aging infrastructure in Wallonia and across the developed world poses serious technical, environmental, and economic challenges. According to data from Service public de Wallonie (SPW), 13% of the bridges (669 structures) suffer from serious degrees of corrosion, while the resources for their rehabilitation are limited. The corrosion in concrete bridges typically occurs due to carbonation, chloride ion ingress or sulphate reaction in the most exposed zones of the bridge, see Fig 1a. To rehabilitate these zones in a sustainable and cost effective manner, a solution using a new generation of materials – ultra-high performance fibre-reinforced concretes (UHPFRC) with compressive strength between 150 and 200 MPa – has emmerged in the past 20 years [1]. UHPFRC materials are characterized by outstanding mechanical properties as well as high durability due to their extremely low permeability [2]. Furthermore, a recent life cycle assessment study has shown that the retrofit of bridge decks with UHPFRC has lower global warming impact than traditional methods [3]. As shown in Fig. 1b, this self-leveling material is cast in thin layers on the deck and around the bridge piers to protect the structure from corrosive environment and significantly extend its service life. In addition, the UHPFRC layers can be used to increase the stiffness and strength of the structure, which is often necessary due to material degradation, increased traffic loads, construction/design errors or damage due to accidental loads.

References :

• Brühwiler, E.: Rehabilitation and Strengthening of Concrete Structures using Ultra-High Performance Fibre Reinforced Concrete. In Alexander, M. G., Beushausen, H.-D., Dehn, F. & Moyo, P., eds. 3rd International Conference on Concrete Repair, Rehabilitation and Retrofitting, 3-5 September 2012 Cape Town (South Africa). London: Taylor and Francis, pp. 72-79.
• Charron, J.-P., Dénarié, E., and Brühwiler, E.: Permeability of Ultra-High Performance Fiber Reinforced Concretes (UHPFRC) under high stresses. Materials and Structures, V. 40, No. 3, 2007, pp. 269-277.
• Habert, G., Denarié, E., Šajna, A., Roosi, P.: Lowering the Global Warming Impact of Bridge Rehabilitations by Using Ultra High Performance Fibre Reinforced Concretes. Cement & Concrete Composites, 38, 2013, pp. 1-11.
• Brühwiler, E.: Renforcement et Réhabilitation des Structures en Béton au Moyen du BFUP Armé. Exposé, Université de Liège, 28 Avril 2016.

  Supervisor : Pr. Boyan Mihaylov

  Researchers : Dr. Renaud Franssen

  Funding : Région Wallonne, SPW Mobilité et Infrastructures

  Budget: 90.000 €

  Duration of project : 24 months

  Start of project : March 2018