钢筋混凝土动态特性的尺寸效应

Currently, reinforced concrete (RC) is one of the main structure and engineering materials in civil and industry buildings，which is widely used in engineering fields.Ningxia lies in high-intensity seismic belt to the northwesten of China, where earthquake occures frequently. To reduce the loss caused by earthquake disaster, it is imperative to investigate the dynamic properties and failure mechanism of reinforced concrete subjected to dynamic loadings such as earthquake.On the basis of theory analysis,experiment and numerical simulation, the influence of specimen dimension and coarse aggregate particle size on the dynamic damage and failure regulation of reinforced concrete under dynamic loading will be further researched. At the same time, the dynamic constitutive relation and damage evolution equation of reinforced concrete will be established; By dynamic loading apparatus, the dynamic compression experiments of reinforced concrete with various reinforcement ratios, specimen dimension and coarse aggregate particle size will be carried out. The damage mechanism and failure characteristics of reinforced concrete with different impact velocity will be analysed carefully. The microscopical responses of reinforced concrete with various reinforcement ratios, specimen dimension and coarse aggregate particle size will be investigated under dynamic loading, which provide experimental results for theory analysis and numerical simulation. By means of finite element and finite difference methods, the whole failure process of reinforced concrete subjected to dynamic loading will be simulated. All mentioned above will provide theory basis for structure design, analysis and better practical engineering application of reinforced concrete.

钢筋混凝土是目前工业与民用建筑中最常用的结构工程材料，在工程领域具有广泛应用。宁夏处在地壳活动强烈的西北地震带区，为了减少地震灾害造成的损失，必须对钢筋混凝土在地震等动荷载作用下动态特性进行研究。本课题采用理论分析、试验研究和数值仿真相结合的方法，深入研究试件和粗骨料尺寸对动荷载作用下钢筋混凝土动态损伤及破坏规律的影响，建立钢筋混凝土动态本构关系及损伤演化特征方程；利用相应动态加载设备加载，探讨配筋率、试件尺寸和粗骨料尺寸不同的钢筋混凝土在动荷载作用下损伤机理及破坏特征，观察配筋率、试件尺寸和粗骨料尺寸不同的钢筋混凝土在高速撞击时内部微(细)观结构响应，校核和完善所提力学模型，同时为理论分析和数值模拟提供实验数据；采用有限元与有限差分的数值模拟方法对配筋率、试件尺寸和粗骨料尺寸不同的钢筋混凝土在动荷载作用下破坏全过程进行数值模拟，为钢筋混凝土更好地工程实际应用及结构设计和分析提供理论依据。

钢筋混凝土是目前工业与民用建筑中最常用的结构工程材料，在工程领域具有广泛的应用。宁夏处在地壳活动强烈的西北地震带区，为了减少地震灾害造成的损失，必须对钢筋混凝土在地震等动荷载作用下动态特性进行研究。该项目利用SHPB试验装置进行钢筋混凝土冲击压缩试验，分析了配筋率和试件尺寸对钢筋混凝土动态特性影响；基于弥散、分层的思想，建立了强冲击荷载作用下钢筋混凝土动态本构模型，给出微裂纹成核和扩展演化方程；将混凝土看成水泥砂浆、粗骨料和两者之间界面相组成复合材料，对试件尺寸、粗骨料体积百分比、粗骨料最大粒径、最小粒径和界面相厚度不同混凝土在不同冲击速度下动态破坏过程进行了数值模拟，揭示试件尺寸、粗骨料体积百分比、粗骨料最大粒径、最小粒径和界面相厚度对混凝土动态特性影响规律,研究表明: 含界面相混凝土表现出明显尺寸效应；随着界面相厚度增大，混凝土峰值应力逐渐减小；保持界面相厚度和粗骨料尺寸不变，随着粗骨料体积百分比增加，混凝土峰值应力呈先增大后减小趋势；保持粗骨料最小粒径和界面相厚度不变，随着粗骨料最大粒径增大，混凝土峰值应力呈现先增大后减小趋势；将钢筋混凝土看作钢筋和混凝土组成两相复合材料，对钢筋混凝土在不同冲击速度下动态破坏过程进行了数值模拟，分析了冲击速度和配筋率对钢筋混凝土动态特性影响,数值模拟表明: 随着冲击速度增加，钢筋混凝土峰值应力明显提高；随着传播距离增加，钢筋混凝土峰值应力呈现逐渐衰减趋势,研究结果为钢筋混凝土更好地工程实际应用及其结构设计和抗震性能分析提供理论依据。