Bending fatigue of macrosynthetic fibre reinforced concrete: experimental program and preliminary constitutive equation

The use of fibre reinforced concrete (FRC) elements without traditional reinforcement is increasing in applications for which the structure is exposed to cyclic loadings, such as pavements, bridge deck overlays and offshore structures. Cyclic loads produce tensile stresses that can lead to crack initiation and propagation, and thus compromising the mechanical performance and durability that may bring about noncompliance with service or limit state requirements. The loss of performance owe to material fatigue-induced strength degradation might be significantly accelerated in cracked cross-sections. This contribution presents the results and outcomes derived from an experimental program on the flexural fatigue behaviour of pre-cracked fibre reinforced concrete carried out on notched 600x150x150 mm beams. The evolution of the crack opening displacement and other design-sensitive parameters were monitored and analysed. The understanding of the damage propagation is the basis for the proposal of a design-oriented constitutive model, which is meant to be used for predicting the fatigue life in cracking-allowed concrete structures designed to be subjected to fatigue-inducing loads. The constitutive model was calibrated for a content (9 kg/m3) of a specific type of macrosynthetic fibre and considering different fatigue load levels.
Postprint (author's final draft)