Torsion of thin tubes with multicell cross-section

It is known that the classical technical theories of Bredt and of sectorial areas are the variational limit of the Saint-Venant torsion problem for ho llow homogeneous isotropic cylinders with thin doubly connected cross-secti on when the wall thickness reaches zero. The main goal of this paper is to prove that the same result remains true for thin tubes with multicell cross -section.