Modeling self-heating and moisture in cementitious materials during fatigue tests using finite element method

Abstract The increasing demand for durable infrastructure has intensified interest in understanding concrete behavior under dynamic loading, particularly fatigue. Although temperature changes have limited influence on concrete’s ultimate strength, they can substantially affect fatigue performance by accelerating microstructural degradation. A notable but insufficiently characterized phenomenon in this context is self-heating, an internal temperature rise observed during cyclic loading. This study examines self-heating in concrete through transient thermal finite element simulations performed on five specimen geometries commonly employed in compressive fatigue tests. The model decouples the mechanical effects, incorporating viscoelastic energy dissipation as the internal heat source. Complementary complex modulus (quasi-static) and tensile fatigue tests were conducted on saturated and dry concrete specimens to provide indirect support for the modelling approach. The simulations reproduced trends reported in literature, including higher temperatures at the specimen core. Simulations revealed that specimen geometry – particularly diameter – was found to strongly govern the thermal response. Saturation increased the complex modulus but had minimal effect on fatigue life. Overall, the numerical results are consistent with the hypothesis that viscoelastic dissipation contributes to self-heating, even if the resulting temperature rise is very small (order of 10 − 4 °C) under tensile fatigue conditions. The agreement between simulations and experiments reinforces that even small viscoelastic effects may contribute to temperature rise under cyclic loading. These findings highlight the importance of considering thermal effects in fatigue analyses and suggest that incorporating viscoelastic mechanisms may improve the representation of heat generation in concrete subjected to cyclic loading, improving durability assessments of concrete structures.