早龄混凝土的压缩与拉伸徐变及其研究现状

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。

Literuture review of compressive/tensile creep of early age concrete

The regularities of early age tensile creep and compressive creep and theories of calculation method for creep stress are key factors for the crack prediction and prevention. Currently, the study on concrete creep focuses on matured concrete, while for early age concrete further study is still needed. The research status, test method and creep stress calculation method of compression and tensile creep for early age concrete are summarized in detail. The results demonstrate that: (1) At present, there is no standard for the test of tensile and compressive creep for early age concrete, and the test data is relatively short. (2) The nonlinear property at low stress level for early age concrete has not been considered in the creep prediction model. (3) The nonlinear creep stress analysis method for early age concrete structures is inadequate. Based on systematically experimental research and solidification creep theory, the nonlinear creep model for early age concrete can be established. With early age tensile creep and compressive nonlinear creep stress considered, finite element simulation accuracy of early age structure should be improved.