混凝土致裂应力与内外约束和徐变的关系

Effect of Internal and External Constraints and Creep on Concrete Cracking Stress

温度变形、自生体积变形和徐变等受内外约束是混凝土裂缝产生的主要原因.为研究水化反应过程中混凝土内部由于温差、温变幅度和线胀系数差异存在的相互制约关系,减少内外约束下温度和自生体积变形及早龄期混凝土开裂,需要对混凝土温度场和应力场进行精确的仿真.通过仿真计算并根据现场模型试验结果对混凝土温度应变、自生体积应变、徐变、内外约束应变进行反分析.研究表明,早龄期混凝土致裂应力主要与徐变和内外约束有关.

Thermal deformation, autogenous deformation and creep under internal and external constraints are the main factors causing concrete cracks. In order to investigate the constraints of concrete caused by asymmetric temperature variation ,difference in temperature and different linear expansion coefficients during the hydration of cement and to reduce the restrained thermal and autogenous deformations resulting from relatively high stress that sometimes causes premature crack- ing in concrete at early ages ,simulation and analysis of the real temperature field and stress field were suggested. Then, based on the results and back analysis,the thermal and autogenous shrinkage,creep,and restrained strains were analyzed. The results showed that the concrete cracking stress at the early age was associated with the creep and internal and external constraints directly.