A theoretical approach for predicting the ultimate resistance of aluminium alloy members subjected to local buckling under uniform compression is presented focusing the attention on box sections. Starting from the J₂ deformation theory of plasticity, the theory of plastic buckling of plates is presented including, as an original contribution, also the variability of the Poisson’s ratio depending on the stress levels. The differential equation of the plates at the onset of buckling is developed and the corresponding solution is provided. Starting from the obtained closed-form solution, the interactive buckling either in the elastic or in the plastic range is analysed. The interaction between the plate elements constituting the member section is explicitly accounted for using a completely theoretical approach where the evaluation of the critical stress leading to local buckling in the plastic range is derived as the value corresponding to the existence of a non-trivial solution for which the determinant of the matrix of the equation system is equal to zero. The accuracy of the plastic buckling theory is pointed out by comparing the buckling resistance obtained by the theoretical approach with the values of the ultimate resistance provided by stub column tests.

Finally, some advances concerning the use of the effective thickness approach, currently adopted by Eurocode 9, are also proposed and herein presented for the first time and compared with test results.

提出了一种理论方法来预测铝合金构件在均匀压缩下承受局部屈曲的极限阻力，并将重点放在箱形截面上。从J _2开始提出了塑性变形理论，板塑性屈曲理论，其中包括作为初始贡献的泊松比随应力水平的变化。建立了屈曲开始时板的微分方程，并提供了相应的解决方案。从获得的封闭形式解开始，分析弹性范围或塑性范围内的相互作用屈曲。构成构件部分的板单元之间的相互作用是使用完全理论方法明确考虑的，其中将导致塑性范围内局部屈曲的临界应力的评估值推导为对应于存在非平凡解的值。方程系统矩阵的行列式等于零

最后，还提出了一些有关使用有效厚度方法的进展，目前已被欧洲规范9采纳，并在此首次提出并与测试结果进行了比较。