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早龄混凝土的拉伸、压缩徐变规律及其结构徐变应力计算方法是对早期裂缝进行有效预测并控制的关键。既有的徐变研究主要侧重于成熟混凝土,而早龄混凝土徐变相关的科学研究还有待进一步深入。对早龄混凝土的压缩和拉伸徐变研究成果、测试方法及其徐变应力计算方法进行了详细综述。研究表明:目前混凝土早龄期拉伸、压缩徐变试验测试尚无规范可循,相关试验数据较为缺乏;混凝土早龄期徐变预测模型基本未考虑其在低应力水平下的非线性性质;早龄混凝土结构非线性徐变应力理论分析方法亦不尽完善。基于系统试验研究和固化徐变理论建立混凝土非线性徐变理论模型,对早龄混凝土结构采用同时考虑受拉和受压不同应力松弛特性的非线性徐变应力理论计算方法,应可提高早龄结构的有限元仿真精度。
The early age concrete tensile, compressive creep law and its structural creep stress calculation method is the key to effective prediction and control of early cracks. Existing creep research mainly focuses on mature concrete, but the creep-related scientific research of early age concrete needs to be further deepened. The compressive and tensile creep research results, test methods and creep stress calculation methods of early age concrete are reviewed in detail. The results show that there is no standard to test the tensile and compressive creep test in the early age of concrete, and the relevant experimental data are lacking. The creep prediction model in the early age of concrete basically does not consider the nonlinear behavior under the low stress level. The theory of nonlinear creep stress analysis of concrete structure in early age is also not perfect. Based on the system experimental research and the theory of solidification and creep, the nonlinear creep theory model of concrete is established. The theoretical calculation method of nonlinear creep stress considering the different stress relaxation characteristics of tension and compression at the same time, Structure Finite Element Simulation Accuracy.