Abstract: Yieldable steel supports are common support forms in deep and weak roadways of a mine, to accommodate the large deformation of their surrounding rocks. The internal forces of a close type yieldable steel support are calculated, in which the support nodes are yielded in the cases of the great loads or large deformation of the surrounding rocks of a roadway. Actually, the underground structure is a hyperstatical structure. The yielding of the support is an irreversible process. And the shape of the support would be changed and the deformation of support would be limited by the ataples of the support nodes after yielding. So, they would produce the internal force in the yieldable steel support. The true internal force of the support after yielding could be got by calculating the residual internal forces due to the yielding of support and the staple’s limited and by adding the internal force due to loads. The results provide a theoretical basis for the design and calculation of yieldable steel supports

Key words: yieldable steel support, residual internal force, staple, internal force of support