Geometrical characteristics of thin-walled rods of open profile

The stress state of the rod structure is characterized by its potential deformation energy. When thin-walled rods are presented in the structure, the integral formula for this energy consists of 11 terms, and each of them contains at least one geometrical characteristic of the rods’ cross-section. The state standards for rolled cross-sections, developed more than 20 years ago, do not contain all cross-section values required for modem computations. To determine characteristics that were not included into the state standards’ description a few approximation formulas existing in academic and reference books are proposed. A new method of cross-section geometrical characteristics’ calculation is proposed. This method takes into account the real shape of the section profile. The obtained results are compared with the results calculated by approximation formulas. Differences for the I-beams and C-beams with sloped internal faces turned out to be very significant.