Abstract A Load Induced Thermal Strain (LITS) semi-empirical model for plain and steel fiber reinforced concrete is proposed, assuming concrete as a heterogeneous 2-phase (matrix + aggregates) material. The effects of dehydration creep and the geomechanical properties decay of the coarse aggregates are taken into account separately in the model by independent parameters calibrated on the basis of the main results on plain concrete available in the scientific literature. The role of the coarse aggregates and the cement content are investigated. It was noticed that the amount of coarse aggregates is directly proportional to LITS, with a logarithmic variation. A comparison between the results of the model with experimental tests in literature, considering different types of concretes (conventional, high strength and ultra-high performance), demonstrated the reliability of the proposed model. Moreover, the model was compared with experimental tests in uniaxial compression on Steel Fiber Reinforced Concrete (SFRC) cylinders with 11-years-old, showing a reasonable approximation. The effect of concrete aging to LITS is also investigated. It is demonstrated that concrete aging is responsible for the reduction of LITS. A reduction factor β(t0) was defined on the basis of a set of experimental values ranging between 28 days and 11 years.

中文翻译：

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单轴压缩载荷作用下普通和钢纤维混凝土的载荷诱导热应变 (LITS) 半经验模型

摘要 假设混凝土为异质两相（基体+骨料）材料，提出了一种用于素混凝土和钢纤维混凝土的载荷诱导热应变（LITS）半经验模型。脱水蠕变的影响和粗骨料的地质力学性能衰减在模型中通过独立参数分别考虑，这些参数基于科学文献中可用的素混凝土的主要结果进行校准。研究了粗骨料和水泥含量的作用。注意到粗骨料的量与 LITS 成正比，呈对数变化。模型的结果与文献中的实验测试的比较，考虑不同类型的混凝土（常规、高强度和超高性能），证明了所提出模型的可靠性。此外，将该模型与使用 11 年的钢纤维混凝土 (SFRC) 圆柱的单轴压缩实验测试进行比较，显示出合理的近似值。还研究了混凝土老化对 LITS 的影响。结果表明，混凝土老化是导致 LITS 减少的原因。根据一组范围在 28 天到 11 年之间的实验值定义了减少因子 β(t0)。结果表明，混凝土老化是导致 LITS 减少的原因。根据一组范围在 28 天到 11 年之间的实验值定义了减少因子 β(t0)。结果表明，混凝土老化是导致 LITS 减少的原因。根据一组范围在 28 天到 11 年之间的实验值定义了减少因子 β(t0)。