In RFEM 6, the results for the FE mesh nodes are determined using the finite element method. For the distribution of internal forces, deformations, and stresses to be continuous, these nodal values are smoothed through an interpolation process. This article will introduce and compare the different types of smoothing that you can use for this purpose.
The punching shear design, in line with EN 1992-1-1, should be performed for slabs with a concentrated load or reaction. The node where the design of punching shear resistance is performed (that is, where there is a punching problem) is called a node of punching shear. The concentrated load at these nodes can be introduced by columns, concentrated force, or nodal supports. The end of the linear load introduction on slabs is also regarded as a concentrated load and therefore, the shear resistance at wall ends, wall corners, and ends or corners of line loads and line supports should be controlled as well.
In RFEM and RSTAB, there are various options to renumber the individual structural elements, such as nodes, lines, members, surfaces, or solids. Two options are available for renumbering: singly and automatically.
If you want to consider guide objects in the overall view (F8 key or double-click on the mouse wheel) or, for example, in a particular direction of the views, you can enable this option in the settings of the particular guide objects (guidelines, background layers, line grids).
In RFEM, if you want to insert a tapered member with intermediate nodes into an existing model, the issue often arises how to determine the individual cross-section depths of the tapered members quickly. The "Connect Lines or Members" command comes in handy for this purpose.
The RF-/LIMITS add-on module allows you to compare the ultimate limit state of members, member ends, nodes, nodal supports, and surfaces (RFEM only) by means of a defined ultimate load capacity. Furthermore, you can check nodal displacements and cross-section dimensions. In this example, the column bases of a carport are to be compared with the maximum allowable forces specified by the manufacturer.
In RFEM 5 and RSTAB 8, you can save problems and warnings occurring during the model check as an extra view. This way, you can easily work through the hints and messages, one after the other, cleaning the model. The function is available for double nodes, overlapping members/lines, and surfaces.
Instead of a quadrangular surface, you can use a B‑spline surface. The shape of this can be adjusted retrospectively, using the integrated help nodes. Depending on the necessary surface complexity, you can create a B‑spline surface with 3 × 3 or 4 × 4 help nodes.
Supports can be copied and moved using drag & drop, even if the "Move/Copy" function is not available in the shortcut menu. This applies to all kinds of supports: nodal supports, line supports, and surface supports. These can easily be assigned to further nodes, lines, or surfaces.
If you want to remove redundant nodes but keep connected objects, you can right-click the relevant node and select the "Delete Nodes" and "Merge Connected Members" options. In addition to members, you can also merge lines in RFEM.
The same structures are often needed in several projects, such as the purlin with columns and braces in this example. The dimensions can be changed directly in RFEM or RSTAB by shifting the nodes.
When modeling in RFEM, double lines may be created. To quickly find and delete them, if necessary, RFEM 5 allows you to export overlapping lines. This is possible, for example, in Excel or in a separate group of sections.
Generally, overlapping members in the model are not desired. To prevent RFEM from deleting an already defined member if another member is placed upon it, select "Allow Double Members" on the "Edit" menu.
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.
In the RF‑/HSS add‑on module, you can analyze the connections for nodes at which hollow sections join. RF‑/HSS performs the ultimate limit state designs according to EN 1993‑1‑8:2005.
This example describes a definition of a planar surface by four nodes that have been imported and seem to lie in a common plane. In reality, they are not exactly in one plane due to (for example) a previous modeling error of a few millimeters. When trying to create a planar surface, the error message "Error in the surface definition! The nodes do not lie in a common plane." appears.
This technical article analyzes the effects of the connection stiffness on the determination of internal forces, as well as the design of connections using the example of a two-story, double-spanned steel frame.
With the RF-STABILITY and RSBUCK add-on modules for RFEM and RSTAB, it is possible to perform eigenvalue analyses for member structures in order to determine the effective length factors. The effective length coefficients can then be used for the stability design.
In RFEM and RSTAB, you can use many interfaces to simplify the modeling of your structure. From background layers, to the import of IFC objects that can be converted into members or surfaces, to the import of the entire structural system from Revit or Tekla. Regardless of the performance of the selected interface, further utilization also depends on the accuracy of the imported data.
If you read out the results of a surface by means of the COM interface, you get a one-dimensional field with all results at the FE nodes or grid points. To get the results on the edge of a surface or along a line within the surfaces, you have to filter out the results in the area of the line. The following article describes a function for this step.
The following technical article describes the creation of a user-defined platform for use on a four-sided tower in the RF-/TOWER add-on modules. First, start with an empty model of the 3D type and define four nodes. The numbering and position of these nodes are very important here.
The deformations of the FE nodes are always the first result of an FE calculation. It is possible to calculate strains, internal forces, and stresses based on these deformations and the stiffness of the elements.
Cable and tensile membrane structures are regarded as very slender and aesthetic building structures. The partly very complex double-curved shapes can be found using suitable form-finding algorithms. One possible solution is to search for the form via the equilibrium between the surface stress (provided prestress and an additional load such as self-weight, pressure, and so on) and the given boundary conditions.
In RFEM and RSTAB, you can import background layers from a DXF file. If the main nodes of the model have already been set, it can be useful to deactivate the snap mode of the background layer.
In RFEM and RSTAB, you can add user‑defined dimension lines to a structural model. When creating these dimension lines, click the objects (for example, end nodes of a line, members, and so on) that represent the reference points of the dimension. If you want to add a dimension line free from the structure previously defined in the model, you have to create an additional free "help node" that acts as a reference object for the new dimension.