等围压约束下超高性能混凝土本构模型

基于损伤力学进行超高性能混凝土(ultra-high performance concrete, UHPC)在围压约束下本构模型的推导,并建立其损伤演化方程;采用UHPC三轴压试验结果对该本构模型进行检验,得到不同围压下UHPC损伤演化曲线.推导的UHPC损伤本构模型,可很好模拟其应力-应变曲线.从损伤整个演变过程可看出, UHPC总损伤劣化程度随着围压提高不断降低,表明围压抑制了损伤的发展并改善UHPC受力状态,使其宏观平均强度增大;与此同时,累积损伤随应变增长趋势减缓, UHPC延性得到增强.

Ultra-high performance concrete constitutive relationship under confining pressure constraint

Based on the damage mechanics, the constitutive relationship of ultra-high performance concrete (UHPC) under confining pressure constraint is deduced, and its damage evolution equation is established. The UHPC conventional triaxial pressure test results were used to test the derived constitutive structure, and the UHPC damage evolution curves under different confining pressure were obtained. The derived UHPC damage constitutive model can simulate the rising section of the stress-strain curve well, but the curve of the descending section is biased, Therefore, it is necessary to construct the correlation between model parameters and steel fiber dosage and Poisson"s ratio with confining pressure in the subsequent study of UHPC constitutive relationship. The process of damage evolution shows that with the increase of confining pressure, the degree of total damage deterioration of UHPC decreases. The confining pressure inhibits the development of damage and improves the stress state of UHPC, so that its macroscopic average strength increases. At the same time, the trend of cumulative damage increasing with strain is slowing down, and the ductility of UHPC is enhanced.