甘肃科学学报

基于Loland模型和Marzars模型的损伤演化方程，研究了硫酸盐环境下混凝土箱梁抗弯刚度的劣化情况。依据Fick第二扩散定律、一级动力学反应原理和钙矾石的膨胀特性，建立了硫酸盐环境下混凝土梁腐蚀前后抗弯刚度的劣化关系模型。利用有限元软件模拟求解未腐蚀状态下试验梁的荷载-挠度曲线，并通过试验验证混凝土梁抗弯刚度的劣化关系模型的可行性和准确性。通过改变试验梁开裂前后的扩散系数，对比分析试验梁在开裂前后抗弯刚度和损伤因子的关系。研究结果表明：试验梁的损伤随时间的增加而增大，硫酸盐对试验梁的腐蚀损伤前3年发展较快，损伤近似呈线性增长，3～7年间损伤速率逐渐放缓，7年后损伤值趋于稳定。此外，裂缝显著加剧试验梁的损伤程度和损伤速率，表明裂缝在硫酸盐侵蚀混凝土结构的过程中不可忽视。

Based on the damage evolution equations of the Loland model and Marzars model, the degradation of the flexural stiffness of concrete box griders under sulfate environments is studied in this paper.Based on Fick's second diffusion law, the first-order kinetic reaction principle, and the expansion characteristics of ettringite, a degradation relationship model for the flexural stiffness of concrete beams before and after corrosion in sulfate environment is established.The load-deflection curve of the test beam in the uncorroded state is simulated and solved using finite element software, and the feasibility and accuracy of the degradation relationship model for the flexural stiffness of the concrete beam are verified through experiments.By changing the diffusion coefficient of the test beam before and after cracking, the relationship between the bending stiffness and damage factor of the test beam before and after cracking is compared and analyzed.The research results show that the damage of the test beam increases with time.The corrosion damage of sulfate to the test beam develops relatively fast in the first 3 years, with an almost linear increase.The damage rate gradually slows down from the 3rd to the 7th year, and the damage value tends to stabilize after 7 years.In addition, the presence of cracks greatly increases the degree and rate of damage to the test beam, indicating that the effect of cracks cannot be ignored in the sulfate corrosion of concrete structures.