Search

The limited understanding of the fatigue behavior of reinforced and prestressed concrete members is one of the reasons why many structures do not reach their expected service life. Without a deeper theoretical understanding of the fatigue phenomena in the various fatigue process zones, reliable fatigue life predictions are not possible. This paper provides a classification of the major fatigue process zones and mechanisms in reinforced and prestressed concrete members, accompanied by a brief review of recent developments in design rules, experimental characterization, and modeling approaches specific to each fatigue process zone and mechanism. The limitations of current approaches to fatigue characterization and modeling are also discussed, highlighting the need for further research in this area. [ABSTRACT FROM AUTHOR]

For a reliable and economical design of concrete structures subjected to fatigue loading, a comprehensive understanding and realistic prediction of concrete fatigue life under complex loading scenarios with variable amplitudes is of major concern. In this paper, experimental investigations of concrete behavior under monotonic, cyclic, and fatigue loading are presented with particular focus on the influence of loading sequence on fatigue life. Namely, a test campaign consisting of 32 three-point bending tests on notched beams was conducted, including two beam sizes and six different loading scenarios. Several response characteristics of the fatigue behavior including, fatigue creep curves, Wöhler curves, stiffness degradation, evolving shapes of hysteretic loops, and crack propagation aspects have been evaluated. In addition, the main dissipative mechanisms governing the flexural behavior of concrete under repeated loading were analyzed based on a wide range of loading scenarios. Furthermore, the effect of loading sequence has been studied and analyzed in detail with the help of a 3D digital image correlation (DIC) system. Based on these observations, a theoretical interpretation of the phenomenology behind the sequence effect under bending loading is provided considering the fatigue crack propagation aspects and the corresponding stress redistribution around the crack tip. • Flexural fatigue behavior of concrete under a wide range of loading scenarios. • Review of experimental investigations of sequence effect on fatigue of concrete. • Critical evaluation of existing damage accumulation rules for flexural fatigue. • Fatigue crack propagation evaluation under variable amplitudes with DIC technology. • Consideration of fatigue crack growth in the interpretation of the sequence effect. [ABSTRACT FROM AUTHOR]

In this paper, combined experimental–numerical investigations of the bond behavior between high-strength concrete and steel reinforcement under monotonic, cyclic and fatigue loading are presented. A modified beam-end test specimen is used to study the bond behavior under push-in compressive loading. The bond length, the concrete strength as well as the bar diameter have been varied in the test program consisting of 56 beam-end test specimens. The bond behavior has been tested under several loading scenarios and the results have been compared with the results of the pull-out tests. Push-through and combined push-through × splitting failure modes have been observed in the test program. Moreover, a bond fatigue model based on a cumulative measure of inelastic slip developed by the authors has been used to demonstrate how to identify the model parameters for a test exhibiting a pure push-through failure. The tests including three design parameters and four distinct loading scenarios will serve for further detailed theoretical research on the bond fatigue phenomenology governing the behavior of reinforced concrete structures. [Display omitted] • Modified beam end test for push-in loading with variable bond length. • High-cycle fatigue bond behavior between steel rebars and high-strength concrete. • Effect of the stabilized splitting cracks on the bond fatigue behavior. • Numerically reproduced trend of splitting crack effect on the bond fatigue behavior. [ABSTRACT FROM AUTHOR]