Abstract: Cyclic loading and unloading tests were performed on concrete specimens under different lateral stresses (0, 0.1f_c, 0.3f_c, 0.5f_c) and strain rates (10^-5/s, 10^-4/s, 10^-3/s, 10^-2/s), respectively, to investigate the energy evolution of concrete in failure process. The evolution and distribution of total energy input, accumulated elastic energy, and dissipated energy along with strain growth under uniaxial compression were obtained. Experimental results showed that when strain rate was 10^-5/s and 10^-4/s, the total energy, elastic energy and dissipated energy of concrete increased at first but then decreased with the rising of strain in the whole loading stage; while when strain rate was at 10^-3/s, 10^-2/s, the aforementioned values augmented with the rising of strain. Under the same lateral stress, the accumulated energy of concrete at failure and the energy storage of concrete increased along with the rising of strain rate; when concrete reached the limit of energy storage, the elastic energy density accounts for 30% at the minimum and 58% at the maximum. When strain rate is constant, the energy storage limit of concrete expanded with the climbing of lateral stress. Lateral stress restrained the development of cracks. When lateral stress was at (0.1, 0.3)f_c, the elastic energy density of concrete increased linearly with the climbing of lateral stress.

Key words: concrete, energy evolution, strain rate, elastic energy, dissipation energy