The authors analyze the theory used in many countries. containing two independent directions: 1) the theory of stability of rod systems. including flat frames; 2) the theory of calculation of structural elements from various materials. The main feature of these theories is the application of the principle of plastic fracture. https://safeersappliancers.shop/product-category/aeg-kme761000b-built-in-combination-microwave-oven-and-grill-in-black/