摘要:The paper describes steel girders optimal design. Steel girders optimal design is based on the strength theory introduced by M. Huber, R. Mises, H. Hencky and on the theory of mirror functions. With the help of out-form volume we can either calculate the optimal form for a girder with variable cross-section or the optimal height for a girder of uniform cross-section. The paper introduces girders calculations according to the authors' methodology. For use this methodology effect of steel saving is about 10-20% compared with a girder or a beam with uniform cross-section. An example of determining optimal shape of a compressed-bend girder the paper describes.