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.
General thin-walled cross-sections often have asymmetrical geometries. The principal axes of such sections are then not parallel to the horizontally and vertically aligned axes Y and Z. When determining the cross-section properties, the angle α between the center-of-gravity axis y and the principal axis u is determined in addition to the principal axis-related moments of inertia.
In RFEM, surfaces are automatically connected if they have common boundary lines. If the definition line of a surface is lying in another surface, the line is automatically integrated into the surface, provided that it is a planar surface. For quadrangle surfaces, however, automatic object detection would be relatively time-consuming. For this reason, the corresponding function is deactivated. The integrated objects must be specified manually.
Until now, if you wanted to determine the centroid of a rectangle, it was necessary to define a line from one corner point to the diagonally opposite point. You obtained the centroid by dividing this line. In RFEM 5 and RSTAB 8, you now have the possibility to create a node between two points. Thus, it is sufficient to select the corner points; then you can determine the distance in absolute or relative values.
To determine the distance between two nodes or the angle between two objects without using the dimensioning function, you can simply use the "Measure" option on the "Tools" menu. Here, you can also choose between various measure functions.
This article describes how to determine the contact force between two objects behaving like walls that are diagonally inclined at a certain angle on top of each other. Define a nodal release to determine this contact force. Since a nodal release requires certain conditions, this article shows two examples.
A fillet weld is the most common weld type in steel building construction. According to EN 1993-1-8, 4.3.2.1 (1) [1], fillet welds may be used for connecting structural part where the fusion faces form an angle of between 60° and 120°.
For situations where no design is available, RF-/STEEL EC3 provides the option to neglect the respective internal forces. Examples of such situations are: bending and compression on angle sections, multi-axial bending for the design according to the General Method, torsion.
In spatial structures, the member position plays an important role in terms of determining internal forces. The orientation of member axes can be defined either by a global cross-section rotation angle, or by a specific member rotation angle. These two angles are added to determine the position of the main axes of a member in a 3D model.
With the SHAPE-THIN cross-section program, you can model the corner areas of cross-sections in detail: The "Smooth Corner" function fills the corner with an element and automatically connects it with a null element. For this, simply click the corner. Use the "Create Round or Angled Corner" function to round or angle the corner. To do this, specify the fillet radius and click both elements.
If a section is not on a straight line but on a curved or angled line, this line has to be defined accordingly as a polyline or a curved line. You can define the section along a line using the "Create Section Numerically" function.
You can quickly model very complex objects in RFEM by rotating lines or polylines. If you need to change the model subsequently, quadrangle surfaces provide an advantage, as they include editable boundary lines.
For structural reasons, shear connections usually include fin plates or flange angles. Main and secondary beams arranged on the top edge require notching or long fin plates. Hinged end plate connections are often welded to the web.
When defining nodal loads, you can rotate the load using several simple options: ~ Rotation by angle around the global coordinate axes in a specific order, ~ Alignment with a user-defined coordinate system, ~ Direction to a particular node, ~ Alignment by means of two nodes, ~ In the direction of a member/line.
Sometimes, it is necessary to rotate graphics in the printout report. In order to also display the result values correctly, you can rotate the results by the respective angle using the Display Properties dialog box. As usual in Display Properties, this setting is to be done separately for the screen view and the printout report.
In RF‑LAMINATE, you can also design curved quadrangle surfaces. In the example in the figure, the cross-laminated timber layers of a chair are designed.
Diagonals of double angles are used for pipe bridge construction and for truss girders, among other things. They are usually subjected to tension, but it is necessary to transfer them in smaller compression forces with regard to the load application. In the case of slender diagonals in particular, you should also consider the bending due to self‑weight.