A column is composed of a concrete section (rectangle 100/200) and a steel section (profile I 200). It is subjected to pressure force. Determine the critical load and corresponding load factor. The theoretical solution is based on the buckling of a simple beam. In this case, two regions have to be taken into account due to different moments of inertia and material properties.
Buckling of Beam with Various Cross-Sections
![Idealized Winter Model](/en/webimage/014811/2948243/01-de.png?mw=512&hash=9f2525444a7414dfb1c05a73e375e9c4fe4f47b1)
![Design Loads and Imperfections for Structural Analysis](/en/webimage/011704/2599265/1626-5-en-us-png.png?mw=512&hash=fa62f0f4ca3d0d5ad78f02510d0c0f076500e2b9)
![Model Description](/en/webimage/008632/2239630/01-de.png?mw=512&hash=9f2525444a7414dfb1c05a73e375e9c4fe4f47b1)
![System](/en/webimage/009648/2419855/01-en-png-6-png.png?mw=512&hash=93bf266af720dc0c66f870b50b746e2f668caebc)
![Feature 002843 | Dimensioning with Result Function](/en/webimage/051576/3982510/1.png?mw=512&hash=9d7f6c198b6d4ae6ee8f2fa8bca75f85579e14c9)
For design objects, you can optionally display sags or extreme results.
![Feature 002423 | Displaying Results in Solids](/en/webimage/031923/3325382/FE_Solid_EN.jpg?mw=512&hash=d2950a5e2123942fab13aad296e814c67695c955)
The results of solid stresses can be displayed as colored 3D points in the finite elements.
![Improved Calculation Performance by Optimized Consideration of Nodal Degrees of Freedom in RFEM](/en/webimage/015531/2983511/Berechnungsperformance_EN_(1).png?mw=512&hash=ea9bf0ab53a4fb0da5c4ed81d32d53360ab2820c)
The number of degrees of freedom in a node is no longer a global calculation parameter in RFEM (6 degrees of freedom for each mesh node in 3D models, 7 degrees of freedom for the warping torsion analysis). Thus, each node is generally considered with a different number of degrees of freedom, which leads to a variable number of equations in the calculation.
This modification speeds up the calculation, especially for models where a significant reduction of the system could be achieved (for example, trusses and membrane structures).
![Extended Display of Surface Strains](/en/webimage/012851/2635393/N_386_02.png?mw=512&hash=8ca45b89302044b96809c681e2688d15a0f63fe4)
Display extended strains of members, surfaces, and solids (for example, the important principal strains, equivalent total strains, and so on) in the Project Navigator - Results in RFEM as well as in Table 4.0.
For example, you can display governing plastic strains when performing the plastic design of connections with surface elements.