【摘要】 为研究混凝土动态力学性能、解释混凝土材料动力破坏机理,该文基于颗粒元(PEM)建立细观模型,模拟混凝土动力弯曲试验,并进行率效应研究。数值仿真中以不同加载速率进行弯曲试验,得到混凝土抗弯强度的率相关强度增长系数(DIF),再现了不同应变率下弯曲破坏模式。数值仿真模拟得到的弯曲应力-应变结果和破坏现象与试验吻合良好,证明了数值模型的有效性。通过对破坏过程进行分析,高应变率条件下混凝土梁产生多条裂纹,表现出与低应变率条件完全不同的破坏形式,这是混凝土动强度提高的主要机理。更多还原

【Abstract】 The meso-scale particle element model(PEM)for concrete was developed for bending simulations and to study the mechanism for strain rate effects on concrete.The numerical results for both strength and fracture patterns match well with experiments.Strength enhancement effects defined as the dynamic increase factor(DIF)are found to be significant.The rupture fracture patterns at high strain rates are quite different from these at low strain rates or static loads.Thus,the occurrence of more cracks at high strain rates is the key factor for the strain rate effects in concrete.更多还原