Understanding Energy Dissipation Behaviour in Cracked Macrosynthetic Fibre-Reinforced Concrete Under Flexural Fatigue Conditions

Fatigue failure results from the propagation of cracks within material as damage accumulates over successive loading cycles. In this context, this contribution presents results and advances derived from an experimental program on the flexural fatigue behaviour of pre-cracked macrosynthetic fibre reinforced concrete carried out on notched 150 × 150 × 600 mm3 beams. Pre-crack considered in this study was 2.5 mm, this adopted as maximum permissible crack width for the ultimate limit state in Model Code 2010 and related to fR3. The upper load value was varied as a percentage of residual flexural strength, fR3. Throughout the testing procedure, evolution of the crack mouth opening displacement (CMOD) alongside various design-sensitive parameters were monitored. The hysteresis loop area was used to analyse the energy dissipation along the fatigue test. An energy dissipation ratio was established to provide a comprehensive understanding of the process up to failure. Three stages of energy dissipation were identified and for each one, a regression equation to describe the behaviour is provided. By using the equation, the energy dissipation ratio can be estimated with a prediction error of 13%. Failure occurred when the dissipated energy surpasses the initial value at the beginning of the test.