Surfaces in building models can be of many different sizes and shapes. All surfaces can be considered in RFEM 6 because the program allows to define different materials and thicknesses as well as surfaces with different stiffness and geometry types. This article focuses on four of these surface types: rotated, trimmed, without thickness, and load transfer.
The size of the computational domain (wind tunnel size) is an important aspect of wind simulation that has a significant impact on the accuracy as well as the cost of CFD simulations.
Spreadsheet programs like MS EXCEL are very popular with engineers because they allow you to simply automatize your calculations and quickly output the results. Therefore, combining MS EXCEL used as a graphical interface with Dlubal's WebService API is an obvious choice. By using the free xlwings library for Python, you can control EXCEL, and read and write values. The functionality is described in the following, using an example.
Using the Concrete Design add-on, concrete column design is possible according to ACI 318-19. The following article will confirm the reinforcement design of the Concrete Design add-on using step-by-step analytical equations as per the ACI 318-19 standard, including the required longitudinal steel reinforcement, gross cross-sectional area, and tie size/spacing.
When calculating foundations according to EC 7 or EC 2, different foundation types or sizes are usually used in one object. However, boundary conditions like the soil parameters, the materials for foundations, concrete covers, and the load combinations selected for design remain the same for all foundations, as a rule.
The display size of the load vectors can be adjusted quickly in the load shortcut menu: Right-click the load icon and select "Increase Display Size" or "Reduce Display Size" from the menu.
The design of cold-rolled steel products is defined in EN 1993-1-3. Typical cross-section shapes are channel, C, Z, top hat, and sigma sections. These are cold-rolled steel products made of thin-walled sheet metal that has been cold-formed by roll-forming or bending methods. When designing the ultimate limit states, it is also necessary to ensure that local transverse forces do not lead to compression, crippling of the web, or local buckling in the web of the sections. These effects can be caused by local transverse forces by the flange into the web, as well as by support forces at the supported points. Section 6.1.7 of EN 1993-1-3 specifies in detail how to determine the resistance of the web Rw,Rd under local transverse forces.
Using RF-CONCRETE Members, concrete column design is possible according to ACI 318-14. Accurately designing concrete column shear and longitudinal reinforcement is important for safety considerations. The following article will confirm the reinforcement design in RF-CONCRETE Members using step-by-step analytical equations as per the ACI 318-14 standard, including required longitudinal steel reinforcement, gross cross-sectional area, and tie size/spacing.
The secondary reinforcement according to DIN EN 1992-1-1 9.2.1 is used to ensure the desired structural behavior. It should avoid failure without prior notification. The minimum reinforcement has to be arranged independently of the size of the actual loading.
Singularities occur in a limited area due to the concentration of the stress-dependent result values. They are conditioned by the FEA methodology. In theory, the stiffness and/or the stress in an infinite size concentrate on an infinitesimally small area.
In RFEM, structures can be modeled and analyzed in a spatial environment. The permanent 3D visualization helps you to better understand complex models and to represent the force flux. However, you can switch from a spatial mode to a planar sheet mode in the documentation of a calculation. To do this, you have to describe the spatial calculation of the structure with all the necessary properties on "flat" paper pages for an independent reader. Usually, you try to display the load actions and the corresponding results by using an orthogonal view of the substructure of the entire structure. Obviously, the load symbols depicted in the 3D mode in a view perpendicular to the load become unrecognizable due the missing expansion. In order to be still able to create a clear representation of all information, the corresponding adjustments are available in RFEM.
The "Page and Sheet Numbering" dialog box allows you to add a prefix to page and sheet numbering. It can be an abbreviation that specifies by chapter all model data in the numbering (for example, with "MO").
For a structural analysis printout in the usual DIN A4 page format, the default settings of 1,000 x 1,000 pixels graphic quality are completely sufficient. However, if the printout should be on a larger page format, you can increase the print quality to a maximum of 5,000 x 5,000 pixels in the Graphic Printout options, or specify a user‑defined value.
Sometimes, a model in the graphic window is displayed without filling the entire window, or with overly large margins after clicking the [Show Whole Model] button. To set the size of the graphic margins, click "Options" → "Display Margins and Stretch Factors". The value specifies the percentage of the margin relative to the graphic window size.
To stabilize the components bearing stability risks, a shear panel and/or a rotational restraint can be defined in RF‑/STEEL EC3. Optionally, trapezoidal sheets, bracings, or individual purlins can be taken into account.
Modern buildings are designed with spaces tailored to personal desires and dreams, expressing individual lifestyles. These requirements often include ceilings - whether in houses, office buildings, or public buildings - that have an enormous span and no support, allowing optimal use of the space below. However, this requires a very high stability level for load‑bearing capacity and serviceability reasons. By extending the size of beam or plate cross-sections, you can increase the stability, but the cost effectiveness decreases because of the additional consumption of material. One common solution for these large spans is to use timber or steel downstand beams.
In RFEM and RSTAB, there are several ways to select a part of the structural model for further processing. The most frequently used selection option is definitely "selection using window". Depending on the size of the structure, the simultaneous selection of several areas of the structure using this option may be time-consuming, since the unwanted model parts are selected as well.
Moving loads can be generated easily with RF‑MOVE Surfaces. A library is available with load models as defined in Eurocode 1, Part 2. The input of step size, offsets at start and end, and the distance to a reference line make it possible for the user to generate user‑defined load models and influence the number of load cases generated. RF‑MOVE Surfaces generates load cases and, optionally, a result combination as an envelope of all results.
"Distribution of load" represents a load actually applied to the system of FE mesh points or FE surfaces. The FE mesh size plays an important role in the loading in the case of line loads and free loads in particular.