Probabilistic assessment of fatigue crack growth in concrete

It is well known to engineers that fatigue accounts for a majority of structural failures. In plain and reinforced concrete structures, fatigue may lead to excessive deformations, excessive crack widths, de-bonding of reinforcement and rupture of the reinforcement or matrix leading to structural collapse. The rate of fatigue crack growth in concrete depends on a number of parameters, such as, the tensile strength, stress history, stress intensity factor range and fracture properties which are random in nature. In this work, the probability of failure of concrete beams under fatigue loading is computed using a modified fatigue law by considering different parameters responsible for fatigue failure as randomly distributed. The sensitivity of different parameters involved in fatigue process pertaining to failure is also studied using stochastic sensitivity analysis. It is seen that the reliability depends on the maximum stress level as well as the cyclic stress range. Further, it is observed that the reliability is more sensitive to the frequency of applied loading, followed by maximum cyclic stress value and the initial notch length, in that order.