The object of research of the study is the bearing capacity of a composite truss. This work aims to analyze the stress-strain state at the site of the bending moment and at the edge of the support brace. To determine the nature and site of destruction, considering the physical nonlinearity of concrete and steel, to determine forces, deflections, and deformations. Method. The Ansys software package is used to assess the stress-strain state, and nonlinear diagrams of materials based on the most modern theories of calculations of concrete and steel are used. Results. Stresses and relative deformations in a reinforced concrete slab and in elements of a metal truss are illustrated. Deflections of the composite truss have been determined. The height of the compressed zone of the composite truss is determined. The character of the dehumidification is determined based on the physical nonlinear operation of concrete and steel. The advantages of the studied section are described.