An improved crack propagation model for plain concrete under fatigue loading

摘要

Fatigue crack growth phenomenon in concrete is complex in nature and is characterised by various parameters. Important crack growth characterizing parameters must be considered in the analysis for accurate crack propagation and fatigue life prediction. In the present work, an analytical formulation has been developed to predict the propagation of crack in plain concrete members subjected to repetitive nature of loading. Dimensional analysis approach for fatigue crack growth problems has been adopted in conjunction with the theory of intermediate asymptotic for the development of the proposed model. The model has been derived considering the effect of critical energy dissipation in fatigue called fatigue fracture energy which can capture the observed size effect in concrete fatigue. Other important crack growth characterizing parameters considered in the present formulation are, change in energy release rate, maximum energy release rate, initial crack length, tensile strength, and ratio of maximum aggregate size to characteristic size of the structure. Further, the influence of fracture process zone has been incorporated in the proposed formulation through the loading parameter. The developed closed form expression has been calibrated with the available experimental results. The applicability of the mathematical model has been verified using the existing experimental results following both deterministic and statistical approach. The dependence of various governing parameters on fatigue life has been demonstrated through sensitivity study.