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为了研究交变荷载对硫酸盐侵蚀混凝土所产生膨胀内应力的影响,引入受交变荷载应力水平及加载频率影响的有效扩散系数,基于Fick第二定律,建立腐蚀与疲劳耦合作用下的扩散反应方程,并采用有限差分法进行求解;在混凝土单轴抗拉强度本构关系的基础上,由膨胀应变计算膨胀内应力,研究交变荷载应力水平、加载频率、外界硫酸盐浓度和水灰比对其膨胀内应力的影响,并应用灰色关联熵对各因素进行分析。结果表明:随交变荷载应力水平、加载频率、水灰比和外界硫酸盐浓度的增加,膨胀内应力产生以及达到极限抗拉强度的时间出现了不同程度的提前,其中,水灰比是影响膨胀内应力的最主要因素;在腐蚀疲劳工况中,混凝土满足设计要求的前提下宜采用较小的水灰比,以提高其耐久性。
In order to study the effect of alternating load on the internal stress caused by sulphate-eroded concrete, an effective diffusion coefficient which is affected by the stress level of alternating load and the loading frequency is introduced. Based on Fick’s second law, a diffusion reaction under the coupling of fatigue and corrosion is established Based on the constitutive relation of the uniaxial tensile strength of concrete, the internal stress of expansion is calculated from the expansion strain. The effects of alternating load stress level, loading frequency, external sulfate concentration and water-cement ratio On the expansion of the internal stress, and the application of gray relational entropy analysis of the various factors. The results show that with the increase of stress level, load frequency, water-cement ratio and external sulfate concentration, the internal stress of expansion and the time to reach the ultimate tensile strength appear ahead of time. Among them, the water-cement ratio is affected In the condition of corrosion fatigue, concrete should meet the design requirements and should adopt a smaller water-cement ratio to improve its durability.