不同湿度混凝土动力抗压性能数值模拟分析

本文基于随机骨料建立了二维混凝土的细观数值模型,利用无厚度cohesive单元模拟界面层及基体的损伤,用弹性单元模拟孔隙水,并结合黏性效应、惯性效应,模拟分析了应变率和孔隙含水率对混凝土抗压强度、峰值应变和弹性模量的影响。结果表明:动力分析时混凝土组成材料采用静力参数,考虑了惯性效应与黏性作用后,数值模型可以很好地反映动力荷载作用下混凝土名义动力强度增长因子(DIF)、单轴压缩弹性模量和峰值应变随应变率增加而增加的宏观现象,以及随着孔隙含水率增加混凝土静动态抗压强度线性减小、DIF线性增加、率效应增强的变化规律。以应变率和孔隙含水率为参数,提出了以干燥混凝土静态抗压强度为基准的含水混凝土动态抗压强度的预测公式。

Numerical simulation on the dynamic compressive performances of concretes with different water contents

A two-dimensional mesoscopic numerical model of concrete was established using randomly distributed aggregates. The no thickness cohesive element was adopted to simulate the damage locating at the interface layer and matrix,and a kind of elastic element was used to simulate the free water in the concrete pores. Both of the viscous effect and inertia effect were considered in the numerical simulation, and the effects of strain rate and moisture content on the compressive strength,dynamic increase factor (DIF), elastic modulus of concrete and peak strain were detailed discussed further. The simulation results show that the macro dynamic responses of the DIF,the elastic modulus,and the peak strain increasing with the increase of strain rates can be simulated well with the incorporation of inertia and viscous effects in the dynamic analysis even though the static mechanical parameters were adopted. In addition,the influences of increasing pore water contents on the dynamic performances of concrete, such as the decrease of static and dynamic compressive strengths and the increases of DIF value and rate effect,can also be simulated. Moreover, the fitting formula of dynamic compressive strength of water-bearing concrete is proposed, taking strain rate and pore water content as parameters,based on the static compressive strength of dried concrete.