Statistical Damage Model of Concrete Considering the Effect of High Temperature Degradation

Based on statistical damage theory, a statistical damage constitutive model for concrete under uniaxial compression is proposed, which considers the high temperature deterioration effect.It assumes that the damage in the compression direction is controlled by the lateral tensile strain; and there are two kinds of damage modes on the mesoscopic scale, rupture and yield, respectively.The effect of high temperature changes the composition and mechanical properties of microstructure in concrete, and then changes the initiation and propagation process of micro-cracks, which could be expressed by the five characteristic parameters in the damage model.In high temperature environments, the intrinsic relationships between chemical and physical reactions, meso-damage evolution mechanism and macroscopic nonlinear mechanical behavior are discussed.It shows that with the increase of temperature, the mechanical properties in microstructure and the meso-damage evolution process of concrete would be significantly changed under uniaxial compression, eventually causes concrete to show the macro-mechanical phenomenon of "weakening".Taking 400℃ as the borderline, the high temperature environment is divided into low-middle temperature zone and high temperature zone; in which the degradation is dominated by different physical and chemical reactions, and the evolution processes of the microstructure mechanical properties and the meso-scale damage exhibit significantly different regularity, respectively. © 2020, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.