Experimental Investigation on Dissipated Energy Evolution Characteristics and Influencing Factors of Concrete under Cyclic Loading

Abstract

In the fatigue design and analysis of concrete structures, an understanding of the dissipated energy characteristics of the material under cyclic loading is important. However, due to the heterogeneity of concrete, the quantitative analysis of dissipated energy is extremely challenging. To investigate the evolution characteristics and influencing factors of dissipated energy, a series of fatigue tests were conducted. Four variable-amplitude cyclic loading schemes were designed to study the relationship between dissipated energy and stress levels, loading frequency, and loading history. The results show a three-phase characteristic of falling-stable-rising in the evolution of single-cycle dissipated energy. The steady value in the second phase is related to the fatigue damage accumulation rate and presents an exponential function with the maximum and minimum stress level. A stress level of 0.75 is considered as the threshold for evaluating the effect of loading history on fatigue damage. The total energy dissipated in the fatigue test has a lower limit close to the energy absorbed in the static test. The relationship between the total dissipated energy and the fatigue life can be described by a linear function in logarithmic coordinates. Based on the evolution characteristics of dissipated energy, a nonlinear fatigue life prediction formula was proposed from the linear damage accumulation model. This study is of great significance for the development and application of the energy-based concrete fatigue damage models.