混凝土应变率效应产生机理探讨

混凝土材料在动载作用下存在应变率敏感效应,其产生机理尚待深入研究。本文进行了全级配混凝土试件的细观数值模拟,分析了地震荷载作用下惯性、阻尼以及其它因素对动载增强效应的影响,讨论了所引入率效应强化参数的物理意义,同时分析了静载和动载作用下混凝土裂缝形态、变形滞后效应和损伤滞后效应。通过混凝土细观力学数值试验,分析研究了有关混凝土材料的声发射试验和CT观测成果、Eibl等人的惯性效应理论以及Stefan效应理论,认为在动载作用下混凝土材料变形的滞后性产生了损伤滞后性最终表现为应变率强化效应。

Investigation on Mechanism of Strain Rate Effects for Concrete

Concrete materials exhibit much sensitivity of mechanical behaviors to loading rates or strain rates, but mechanism of strain rate effects induced is not well understood. The meso-mechanical simulations of specimens of fully-graded concrete are conducted to investigate the influence of inertial force, damping force on the dynamical strength enhancing coefficients. Cracking patterns, damage delay of concrete under static and dynamical loading are examined on the basis of the related Acoustic Emission tests, CT images of crack of concrete, the inertial theory of Eibl et al. and Stefan effects. It is concluded that the enhancing effects of strain rate of concrete can be considered as the results of damage delay from deformation delay produced by inertial effects, capillary water effects and other factors.