Experimental investigation of the flexural fatigue behaviour of a High-Performance Fibre Reinforced Concrete (HPFRC)

Several structures and infrastructures, including bridge decks, airport pavements, industrial floors, offshore platforms, and energy harvesting systems, experience, during their service life, significant cyclic loading due to traffic, machine vibrations, wind, waves, and thermal variations. In recent decades, High-Performance Fibre Reinforced Concrete (HPFRC) has gained traction as a suitable material for these applications, owing not only to its high strength but also to the enhanced properties provided by the fibres, including increased toughness and durability. Characterising the fatigue behaviour of HPFRC, especially under flexural stress (which is crucial for many of the aforesaid structures), is therefore of great relevance. To this end, this work presents a thorough investigation of the fatigue behaviour in flexure of a tailored HPFRC mix with hybrid fibres, through an extensive experimental campaign encompassing tests up to cycles and four different upper load levels. Subsequent tests focus also on the role played by pre-cracking of the specimens and by the loading frequency. The evolution of damage has thus been studied relying on the measured residual strengths after cycling as well as on the evolution of the Crack Mouth Opening Displacement (CMOD) and its derivative. Moreover, considering the requirements of designers, custom – curves for this material are presented and compared with existing models in current design codes.