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.