Analyse structurale d’un pont composé de BFUP et de béton armé

Aujourd’hui, le béton armé est le matériau de construction le plus utilisé. Il possède une performance satisfaisante dans la plupart des applications, cependant il présente un manque de durabilité sous des conditions sévères, en particulier dans le cas des structures existantes construites il a y plusieurs décades qui peuvent présenter des dégâts importants. L’utilisation des bétons fibrés ultra-performants (BFUP) dans des éléments composés pour augmenter la durabilité est une option prometteuse, vu le potentiel extraordinaire de ces matériaux. Dans ce type d’applications le retrait des couches protectrices en BFUP entravé par le béton existant joue un rôle important. Une section transversale d’un pont conceptuel, composé de béton armé et de BFUP, a été analysée numériquement. Deux paramètres principaux, la résistance en traction ainsi que la capacité d’écrouissage ont été variés. L’analyse montre l’importance de l’écrouissage du BFUP, l’influence de sa résistance en traction sur la réponse structurale dans des conditions de retrait entravé (déformation imposée), ainsi que sous l’effet des charges de trafic (force imposée). Les résultats obtenus valident l’utilisation de couches minces en BFUP pour l’augmentation de la durabilité des ouvrages en béton

Structural analysis of a composite bridge structure combining UHPFRC and prestressed concrete

Reinforced concrete being the most applied construction material today performs very well in most applications but still lacks durability under severe environmental conditions. Especially existing structures built decades ago show degradation. Using Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) to improve durability is a promising option seen the extraordinary performance of this material when applied in a composite section. Restrained shrinkage of the overlay plays an important role in this type of application. A conceptual bridge cross section combining UHPFRC and reinforced concrete has been numerically analysed. Two main parameters, tensile strength and strain hardening capacity, were varied. The analysis indicates the importance of strain hardening of UHPFRC and the influence of its tensile strength on the structural response under restrained shrinkage (deformation controlled loading) and traffic loads (force controlled loading). The results validate the concept of using a UHPFRC layer to improve the structural durability of concrete constructions

Ultra high performance fiber reinforced concrete for strengthening and protecting bridge deck slabs

An original concept is presented for the durable rehabilitation of concrete bridge deck slabs. The main idea is to add a layer of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) with or without steel reinforcing bars over the concrete slab to create a composite section. The layer of UHPFRC strengthens the structural element for high traffic loads. Experimental studies on composite beams and slabs were carried out to study their behavior under various types of loading and identify the failure modes and the contribution of the UHPFRC layer to the resistance. Analytical models were then developed to calculate the resistance of composite beams. The concept has been validated by field applications demonstrating that the technology of UHPFRC is mature for cast in-situ

Structural Behaviour of UHPFRC Combined with Various Grades of Reinforcing Steel

Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) is a promising building material for applications where high compressive and tensile strengths, deformability and increased durability are required. Especially for the rehabilitation of existing structures, the addition of a thin cast-in-place UHPFRC layer onto a reinforced concrete member is very efficient. Structural resistance and deformability can be even more improved by incorporating reinforcing steel bars in the UHPFRC layer. To highlight the potential in terms of structural resistance and deformability and to reduce the variability of the mechanical properties of plain UHPFRC, UHPFRC with bar reinforcement is investigated in view of a reliable prediction of the structural response. This paper presents the results of an experimental program that serves to identify the fundamental structural response of reinforced UHPFRC, influenced by various types and ratios of reinforcement and their bond behaviour. These results validate an analytical approach considering the bond-slip law, the strain compatibility and the formation and opening of cracks. The understanding of the structural behaviour of reinforced UHPFRC establishes the basis to comprehend the behaviour of composite members combining reinforced UHPFRC and reinforced concrete