Fatigue of Concrete under Random Loadings

Abstract

A fatigue model is presented for plain concrete subjected to random loadings in compression. Hysteretic nonlinear behavior of concrete is incorporated to express the cumulative fatigue damage in terms of the residual plastic strain. A dual-coordinate system is used to model the envelope curve in compression and the hysteresis loops within the envelope curve. The equivalent linearization technique is utilized to obtain the root-mean-square (RMS) response statistics of hysteretic nonlinear behavior of concrete. Available fatigue test data are analyzed to obtain an optimal form of damage function and calibrate the model. Constant amplitude and random loading tests are used for this purpose. A practical formulation is presented to evaluate fatigue failure probability based on the assumption that the loadings are narrow-banded Gaussian processes. The variabilities both in loading and capacity are incorporated in the formulation. The method can be used to evaluate the fatigue damage and failure probability of critical elements in the reliability analysis of concrete structures.