In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.
Frequently Asked Questions (FAQ)
Customer Support 24/7
According to DIN EN 1993‑1‑1, 220.127.116.11 (2), the reduction factor χLT can be modified by the f factor for χLT,mod. You can activate or deactivate this option under National Annex Settings.
AnswerIn addition to the stability analysis in Sections 6.3.1 to Section 6.3.3 of EN 1993‑1‑1 (Equivalent Member Method), RF‑/STEEL EC3 also provides the General Method according to Section 6.3.4 of EN 1993‑1‑1.This can be extended with the following options:~ The European lateral-torsional buckling curve, which is regulated in the German National Annex to EN 1993, for example.~ Extension of biaxial bending according to the dissertation by Dr. Naumes.~ The interpolation between lateral buckling and lateral-torsional buckling.When designing sets of members according to the General Method, a window is available in the Window "1.7 Nodal Supports - Sets of Members" where the nodal supports are displayed graphically on the set of members. In this way, the General Method represents a useful supplement to the other design methods, which has proven itself, particularly when designing tapers. It is not necessary to enter effective lengths in this method.In the "Details" of the add-on module, you can select the method to be used for sets of members in the "Stability" tab (see Figure 01).The equivalent member method may only be used for straight sets of members with a uniform cross-section (that is, not for tapered joints). For members with a variable cross-section, use the preset General Method.
RF-/ALUMINUM checks the symmetry of general cross-sections and compares them with the SHAPE-THIN evaluation if activating the "Determine symmetry by module and compare with SHAPE‑THIN definition" check box (Figure 01).
If both methods provide different results, the corresponding error message appears (Figure 02).
Usually, there are small inaccuracies in the SHAPE‑THIN cross-section. Thus, the cross-section Sec‑1.du9 shown in Figure 03 is not absolutely symmetrical to the Z‑axis: The Z‑coordinates of Node 1 and Node 4 as well as Node 55 and Node 60 do not match in the second decimal place.
SHAPE‑THIN classifies the cross-section as asymmetrical, but RF‑/ALUMINUM as monosymmetric to the z‑axis, so the error message shown in Figure 02 appears.
The SHAPE‑THIN cross-section should be checked for symmetry. When modeling in SHAPE‑THIN, it is useful to only display one side of the cross-section and to create the other half by mirroring. This is also shown in the video.
AnswerThe design points in CRANEWAY have been adopted in compliance with the standard. In this case, the stresses are calculated for the following locations:
These points are not displayed in the resulting cross-section graphic in the CRANEWAY program. However, there is always a stress point at the design points 0 and 2 for which the result values can be directly displayed.
- Design Point 0
A periphery of the flange at the web edge or at the fillet start
- Design Point 1
A flange at load application point (this can be checked as wheel spacing in Window 1.4)
- Design Point 2
The flange edge
- Design Point 0
AnswerIn the graphic, imperfections are always oriented on a support. In the attached model and in Figure 01, the only support of an imperfection is defined at the column head. Therefore, the imperfection is oriented at this point.Since the graphical imperfection is virtually an equivalent load, the display is only of visual relevance in this case. The display is not important for the calculation.In order to orientate the imperfection graphically to the upper column head, you could use a rigid member, for example, and arrange the support there (Figure 02).
RF-CONCRETE Columns determines the equivalent moment M0e from the moment M02 at the column head and M01 at the column base according to EN 1992‑1‑1, 18.104.22.168 (2), and performs the design according to the model column method with this equivalent moment M0e.
Now, it may happen, for example, that a computationally larger required reinforcement area would result from the cross-section design with the moment M01 at the column head.
To ensure this, message 28) is displayed, according to which the user should perform a standard design with the internal forces according to the linear static analysis. To do this, simply open the RF‑CONCRETE Members add-on module and perform pure design of the internal forces according to the linear static analysis for the member designed in RF‑CONCRETE Columns.
RF-/STEEL Cold-Formed Sections is a module extension of RF‑/STEEL EC3. The only thing you need to do is to activate the design for cold-formed cross-sections in the detailed settings of RF‑/STEEL EC3 (Figure 01).
Common cold-formed cross-sections can be modeled in SHAPE‑THIN. In General Data, select the "c/t parts and effective cross-section properties" check box (Figure 01).
Then, select the "EN 1993‑1‑3 (Cold formed cross-section)" option in the "c/t-Parts and Effective Cross-Section" tab of the Calculation Parameters dialog box (Figure 02).
You can optionally check the geometric conditions for the applicability of the standard specified in EN 1993‑1‑3 , 5.2. To do this, select the corresponding check boxes. If the geometric conditions are not met, an error message appears before the calculation.
First, enter the elements of the cross-section. The notional flat widths are usually generated automatically from the geometry conditions, but can also be created as user-defined in Table "1.7 Notional Flat Widths | EN 1993‑1‑3" (Figure 03) or in the corresponding dialog box.
Then, you can define stiffeners in Table "1.8 Stiffeners" or in the corresponding dialog box (Figure 04).
Furthermore, you should specify the buckling panel in Table "1.9 Buckling panels" (Figure 05) or in the dialog box. To do this, select the elements of the buckling panel. The stiffeners located in the stiffened panel are identified automatically.
For the design of a cold-formed cross-section in RF‑/STEEL Cold‑Formed Sections, it is sufficient to define the stiffeners and panels of the cross-section. It is not necessary to additionally calculate the effective cross-section in SHAPE‑THIN. Thus, you can start the calculation and click "OK" to confirm the warning message (Figure 06).
After saving the calculated cross-section, it can be imported into RFEM or RSTAB.
AnswerThe reason for the different results is probably the settings of effective lengths for the stability analysis. According to the default setting, these are determined automatically in the RF‑/CONCRETE Columns add-on module. However, this method does not work for divided members, and thus no stability analysis is performed (a corresponding warning message appears).If you have entered the effective lengths manually, this only applies to a single member. In order to perform a correct stability analysis of the column as an entire structural component, it is necessary to define it as a set of members.
AnswerThe PLATE‑BUCKLING add-on module allows you to only calculate rectangular buckling panels.The panel is entered in Window 1.1 of the add-on module. Another option is to create the panel from an existing RFEM or RSTAB file by selecting the respective c/t-part.
Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you for the valuable information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”