钢筋混凝土梁冲击响应的3D细观力学模拟

3D meso-mechanical modelling of impact response of reinforced concrete beams

钢筋混凝土结构在冲击载荷作用下响应和破坏的研究受到了广泛的关注.本文通过建立3D细观力学模型,并结合新近研发的混凝土动态计算本构模型,模拟计算冲击载荷作用下钢筋混凝土梁的响应和破坏.3D细观力学模型假定混凝土是由砂浆基体、粗骨料和界面过渡层(Interfacial Transition Zone,简称ITZ层)三相组成的复合材料.混凝土动态计算本构模型考虑了压力相关性、剪切损伤、拉伸损伤、Lode角效应和材料应变率效应等主要因素.结果表明:数值模拟得到的冲击载荷、梁跨中点挠度的时程曲线以及裂纹的分布和扩展模式与实验结果吻合得较好;新提出的混凝土3D细观力学模型和新近研发的混凝土动态计算本构模型可以用来预测钢筋混凝土结构在冲击载荷作用下的响应和破坏.

An understanding of the response and failure of reinforced concrete structures subjected to impact loadings is of great importance in safety calculations and assessment in civil as well as defence engineering. In this paper, a numerical study is performed on the impact response of reinforced concrete beams by a newly proposed 3D meso-mechanical model together with a recently developed computational dynamic constitutive model for concrete. In the 3D meso-mechanical model, concrete is considered as a three-phase composite material consisting of mortar matrix, coarse aggregates and interfacial transition zone （ITZ layers）. The constitutive model for concrete takes into account pressure dependency, shear damage, tensile softening, Lode effect and strain rate effect, etc. It is shown that the numerical results are in good agreement with the experimental observations in terms of time histories of impact force and displacement as well as crack distribution and propagation and that the newly developed 3D meso-mechanical model together with the previously proposed constitutive model for concrete can be used to predict the response and failure of reinforced concrete structures subjected to impact loading.