混凝土三点弯曲梁随机骨料模型的开裂模拟

Simulation on Cracking of Random Aggregate Model of Concrete Three-Point Bending Beam

在试验表征及工程实践中,仿真可以准确反映裂缝的发展规律.采用内聚力模型来研究混凝土梁三点弯曲试验的宏观力学性能和细观开裂损伤破坏行为.在三点弯曲试验中的受力破坏的全过程研究中,对I型断裂能、II型断裂能、抗剪强度、抗拉强度及弹性模量(刚度)这5个控制单元开裂的关键参数进行了反演研究.通过宏观力学性能和细观开裂的试验结果,对一组试件的试验结果与参数化模型结果进行逆推分析,得到了控制因素在模拟中适用的参数范围.然后结合不同配合比试件的骨料定量化信息,对3个骨料面积不同的模型,应用已得到的参数范围中值来模拟获得裂缝扩展的定量结果,并对照模拟与试验的力学性能和裂缝量化结果验证参数范围的准确性.

Accurate description of concrete crack propagation is of great significance to practical engineering.This paper adopts the cohesive zone model(CZM)to investigate both the macro-mechanical properties and the micro-cracking damage behavior of concrete beams in a three-point bending test.Throughout the study of damage under loading in the three-point bending test,parametric examinations are conducted on five key factors controlling the cracking of cohesive elements regarding the case of circulate aggregate,namely type I fracture energy,type II fracture energy,shear strength,tensile strength and elastic modulus(stiffness).Through the test results of macro-mechanical properties and micro-cracking,the test results of a group of specimens and the results of parametric models are reversely analyzed,and the applicable parameter range of control factors in three-point bending simulation is obtained.Three computation models with different aggregate areas are established by taking account of the quantitative aggregate data from specimens with different mix proportions.The parameter range is then applied to derive quantitative results related to crack propagation.Eventually,the accuracy of the parameter range is validated against both the mechanical properties and quantitative crack data obtained from simulations and experiment.