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Accueil du site > Equipes de recherche > Matériaux et Structures Architecturés (MSA) > Diagnostic réparation et réhabilitation > Reparation, reinforcement and retrofitting

Reparation, reinforcement and retrofitting

A large number of bridges, buildings and other structures require thermal rehabilitation and strengthening due to many problems associated with their deterioration and to the new environmental standards. An important activity of MSA is linked to such topics which couple experiments and development of original modellings.

This is because many buildings and engineering structures require retro-fittings due to both age and new environmental requirements that MSA is deeply involved in these topics.

These topics are treated according to two complementary ways :

- The first one, very "mechanical" proposes the study of the mechanical principle of healthy or damaged structures with the aim of the implementation of effective devices to improve the performance and the life cycle.
- The second, concerns the optimization of the energy rehabilitation of buildings, by proposing innovative structural concepts of envelope and decision-making tools concerning the strategies of rehabilitation.

Mechanical studies

  • Rail platforms durability

The study of the degradation of the urban railroads, high-speed railway and tracks in the tunnel is a speciality of the team. The components of the rail tracks (ballasted or concrete slabs tracks) were studied within the framework of fatigue and cracking via numerical models and experimental tests.

  • Concrete durability

Ultra high performance fibre reinforced concrete, green concrete or normal concrete are the object of a lot of works of the team. Fire performance and study of alkali-silica reaction anisotropy are examples of studied phenomena which it is important to know how simulate to predict the residual life cycle of damaged structures. Another study concerns the use of carbon fiber reinforced plastic bars to prestress ultra high performance fibre reinforced concrete to provide lighter structures, durable in aggressive/corrosive environment which require less maintenance. Micro-mechanical approaches and experiments are the main search tools.

  • Strengthening of structures using externally bonded FRP composites

This method of strengthening has emerged very popular around the world for the repair of structures. MSA is deeply involved in these topics. For example an analytical model allowing to predict the ultimate loading capacity of strengthened beams and slabs. Nevertheless, this type of reinforcement may cause a premature and brittle failure such as plate end interfacial debonding or concrete cover separation. Then the first step for a successful, safe and economic design of flexural strengthening using FRP composite at the bottom of the beam is then to predict such failure and to take it into account in design.
A nonlinear finite element analysis was carried out to predict ultimate loading capacity and the failure mode of RC beams in a four-point bending setup. Comparisons between the predictions of the numerical model and test results show a very good agreement.

A special attention is also given to the repair and strengthening of wood structures. Experimentations and simulations concerning multi-reinforcement of glulam with carbon strips inserted between layers of wood, have permitted to highlight the interests of this innovative proposal. Experimental results indeed show an increasing of ultimate performance and apparent ductility.

Réhabilitation énergétique

  • Optimisation du captage Photovoltaique ou solaire thermique de bâtiments

Il a été mené une exploration du potentiel de la forme pour l’optimisation du captage Photovoltaique ou solaire thermique de bâtiments (support Ademe/CSTB). Des formes optimales ont été produites via des algorithmes génétiques multicritères avec prise en compte de nombreuses variables. Cette activité est en lien étroit avec l’utilisation potentielle des gridshells élastiques étudiés par l’équipe.

  • Optimisation multicritère de la réhabilitation énergétique de parcs immobiliers

Une approche systémique menée en collaboration avec l’école des mines et Vinci, a proposé une optimisation multicritère de la réhabilitation énergétique multi-solution de parcs immobiliers, là encore par algorithmes génétiques. Des outils d’aide à la décision concernant les stratégies de réhabilitation ont ainsi été développées et permettront aux bailleurs immobiliers l’optimisation du retrofitting de leurs parcs.

Some pictures and illustrations...

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Mechanical behavior of a balasted track, 3 slabs exerimentation.

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Reinforced concrete with carbon strips : tests and ULS simulations

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Peeling-off modelisation for concrete reinforced with carbon strip

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Glulam multi-reinforced by carbone-epoxy laminates and a crack in the wood stopped by such an architecture

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Reinforced glulam : 3m long beam and simulations

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Prestressed carbon rods in a concrete beam (right : aparatus for initial prestressing)

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Optimal shapes for a better energetic efficiency, with mask effect and for different latitudes

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