为了解决循环加卸载问题，将隶属度函数和模糊截集引入到塑性屈服函数中，并采用米塞斯屈服准则，将屈服函数模糊化，推导得到了模糊弹塑性本构模型。随着隶属度值的变化，该模型的弹塑性界面能连续过渡，且表达式简单，加卸载路径明了；利用该模型对钢桥面板在循环荷载作用下进行了分析，并通过有限单元法得到了数值解；通过分析发现，模糊弹塑性模型通过隶属度的演化能代替硬化规律，能很好地反映循环加卸载过程，是解决循环加卸载作用下弹塑性连续过渡的一种有效途径。

The membership function and the fuzzy deadline set are imported into the plastic yield function to solve the loading-unloading problem in which the Von Mises yield criterion is adopted to deduce the fuzzy plastic yield function. Taken the strain rate into consideration, the fuzzy elastic -plastic constitutive model is obtained. The advantages of this model are consecutive with the changes of the membership, simple in expression and clear in route of loading and unloading. In analyzing Steel panele under the interior cyclic loading based on the model, the numerical solutions are obtained by the finite element method. It is shown that the cyclic loading process could be simulated well by the model and it is an effective way to solve the consecutive elasto-plastic problem under cyclic loading.