Analysis of the influence of local stress on the carrying capacity of box beams

Abstract

This paper presents the identification of influence of local stress on the carrying capacity of box beams with quadrilateral cross section using the method of decomposing the cross section of the beam into its structural elements (plates). A mathematical model of the box beam was created on the basis of this methodology from the aspect of local stress. Deformation and stress parameters (deflection, moment and stress) of the constituent plates were defined. A comparative analysis of the results, i.e. deformation and stress values for the rectangular and trapezoidal cross sections was carried out. It was done under the same conditions of global carrying capacity and for the same ratio between the area of cross section and the resistance moment of the beam area. It was shown that the local stress can have the intensity which is several times higher than that of the global stress and that the selection of an appropriate cross section of the beam can significantly reduce the local effects. The results of research into the influence of local stress on the total carrying capacity of box beams were verified by means of the finite element method (FEM) using the software package ANSYS 12.