基于强度包络理论的混凝土疲劳剩余强度计算模型

Calculation Model of Concrete Fatigue Residual Strength Based on Strength Envelope Theory

为了研究疲劳荷载作用下混凝土剩余强度退化规律,基于强度包络理论,推导了混凝土经历任意次数疲劳加载后的剩余强度包络线方程,建立了任意次数疲劳加载后的混凝土剩余强度计算模型,并用试验进行了验证分析。研究结果表明:模型假设的疲劳破坏判据正确,选择的剩余强度包络线合理;计算结果符合混凝土剩余强度退化规律并满足边界条件,模型能有效模拟混凝土在疲劳过程中的剩余强度退化规律;因引入线性损伤函数,模型计算的混凝土剩余强度退化规律更接近线性变化,而试验趋向于非线性变化,应力水平越低这种倾向性更明显;特定疲劳次数剩余强度计算值接近试验值,平均误差只有2%。

In order to study the deterioration of the residual strength of concrete under fatigue loading,based on the strength envelope theory,the envelope equation of the residual strength of concrete after any cycles of fatigue loading is derived,and the calculation model of the residual strength is established,which is verified by a test. The result indicates that（ 1） the fatigue failure criterion of the model assumption is correct,the selected residual strength envelope is reasonable;（ 2） the calculation result is in line with the residual strength deterioration and meets the boundary conditions,the model can effectively simulate the deterioration of residual strength of concrete in fatigue process;（ 3） because of the introduced linear damage function,the model calculation result of the residual strength is close to linear change,but the test tends to nonlinear change,the lower the stress level the more apparent the tendency;（ 4） the calculation result of the residual strength in some certain fatigue cycle is close to the experimental values,the average error is only 2%.