Damage assessment of RC arch structures using fractal analysis of crack patterns

Surface crack patterns can easily show the behavior of concrete elements and structures. However, visual damage inspection performed by experts is a subjective approach and is prone to inaccuracies. The quantification makes this process objective and more reliable. In that regards, the maximum crack width is used as a practical measurement. It has been shown that the crack width is not a good indicator of damage due to its inherent uncertainties; In fact, it might bounce back after unloading. As such, a dimensionless parameter so-called Fractal Dimension has been introduced as a robust index that can quantify the complexity of crack distribution efficiently. The present study aims to investigate the relation between crack pattern and stiffness loss of RC arch structures. An experimental program, constituting four RC arch specimens, is also conducted and the structural behavior and the surface crack pattern results are captured during the test. The results of analysis show that the Fractal Dimension representation of the crack pattern provide satisfactory correlation with experimentally obtained tangential stiffness and can be recommended for use as a quantized visual damage index.