When a concrete slab is set upon the top flange, its effect is like a lateral support (composite construction), preventing problems of torsional buckling stability. If there is a negative distribution of the bending moment, the bottom flange is subjected to compression and the top flange is under tension. If the lateral support given by the stiffness of the web is insufficient, the angle between the bottom flange and the web intersection line is variable in this case so that there is a possibility of distortional buckling for the bottom flange.
For a frame trussed from below, compression members are to be modelled perpendicular to the inclined beam. The member length and the intersection with the horizontal beam are defined.
Often in RFEM, only part of a surface must be loaded, not an entire surface. A typical case of this is soil pressure. For this purpose, there is the option of defining free surface loads. They are surface-independent and are displayed in defined coordinate dimensions in the graphic.
If you want to model two intersecting surfaces, RFEM offers you the possibility to create the section line automatically. In the program, this function is referred to as intersection. When generating an intersection, the modeled surface is split into components. This has the advantage that the components can be taken into account in the determination of the internal forces, or deactivated.
If intersections created in RFEM 4 are opened in an RFEM 5 file, the file management of intersections remains in the old format for compatibility reasons. Thus, the individual partial surfaces of the intersection can be activated or deactivated using only the "Integrated/Components" tab, all partial surfaces can only have the same thickness, and it is impossible to use the separate FE mesh refinement for the individual surface components.