Localization of plastic buckling patterns under cyclic loading

This study investigates the theoretical aspects of the localization of plastic buckling patterns, which results in the strength deterioration of steel structures under cyclic loading. Because the localization phenomena is caused by the plastic bifurcation from the decreasing equilibrium path in the post-peak range, we first presented a method based on the finite-element method (FEM) to analyze the plastic bifurcation. Then, using the proposed method, we analyzed a multiply supported column and simply supported rectangular compression plates subject to repeated loading. As a result of numerical anlysis, it was confirmed theoretically that the localization of buckling patterns has a large influence on the strength deterioration under cyclic loading. Furthermore, it was observed from the numerical results that the occurrence of localization is accelerated by the accumulation of residual bending deformations as well as the Bauschinger effect of materials.