In addition to our technical support (e.g. via email, chat), we also offer an extensive range of free online services available 24/7 on our website.
Frequently Asked Questions (FAQ)
Customer Support 24/7
You have probably defined a shear panel and a rotational restraint for your design case in the RF‑/STEEL EC3 add-on module, but have not yet defined all specifications for the rotational restraint.
In Window 1.13, scroll down under Settings. For the rotational restraint, the "spacing of beams" is still defined as s = 0 m. Adjust the value accordingly.
In principle, the program always tries to perform a plastic design for cross-section classes 1 and 2. However, if torsion is additionally contained, the design can only be performed elastically. This is due to the interaction conditions according to EN 1993-1-1 clause 6.2.9, which do not include any torsional component.
For this reason, the "Cross-Section Design and Torsion" setting is available in the details of the add-on module. By adjusting the limit shear stress for the cross-section designs, you can also neglect the torsion under your own responsibility.
AnswerTapered members must not be designed according to the simplified equivalent member method!For steel structures, the design can be performed by considering the warping torsion or using the General Method. These methods are described in this technical article.For timber structures, the design can also be performed by considering the warping torsion. The method for timber structures is explained in detail in thiswebinar.According to the equivalent member method, the design can be performed if the provisions of the explanations for DIN 1052, Section E8.4.2 (3) for variable cross-sections are met. In various sources of technical literature, this method is adopted for Eurocode 5. An example of this can be found in the document on brettschichtholz.de, page 64 ff.In the RX‑TIMBER program, the design of tapered members is performed according to the equivalent member method. This is briefly explained on a simple example.Structural System (Figure 01):
No stiffening is defined. The lateral-torsional stability becomes governing with 99% (Figure 02) at the x‑location 1.598 m. The cross-section height is 36.8 cm. However, the slenderness ratio is based on the equivalent cross-section height of 60.9 cm (Figure 03).The equivalent cross-section height results at the x-location 5.2 m about 0.65 × 8 m = 5.2 m.If the stiffening is in the middle of the span, for example, the equivalent height for the x‑location changes to 45.3 cm.Since the stiffening is usually applied over the member length, the height must be calculated according to a special algorithm. The supports are always applied as fixed points and the equivalent heights are calculated, based on the x-locations of the designs.For the example, the following results: x0.65 = 0.32 x 4 m + 1.598 m = 2.878 m
- Span length: 8 m
- Beam height right: 80 cm
- Beam height left: 26 cm
- Roof inclination: 3.9°
The following code displays all elements of the STEEL EC3 add-on module that can be modified via the COM interface:// get interface to active modeliModel = iApp.GetActiveModel();// get interface to STEEL EC3 moduleIModule module = iModel.GetModule("STEEL_EC3") as Dlubal.STEEL_EC3.IModule;// get interface to module caseICase iStEC3case = module.moGetCase(1, Dlubal.STEEL_EC3.ITEM_AT.AT_NO);// get ultimate limit state options (Details > Ultimate Limit State)ULS_OPTIONS optsULS = iStEC3case.moGetULSOptions();// get options for stability design (Details > Stability)STABILITY_OPTIONS optsStab = iStEC3case.moGetStabilityOptions();// get options for serviceability design (Details > Serviceabiltiy)SERVICEABILITY_DEFORMATION_TYPE optsServDef = iStEC3case.moGetServiceabilityOptions();// get fire resistance options (Details > Fire Resistance)FIRE_RESISTANCE_OPTIONS optsFire = iStEC3case.moGetFireResistanceOptions();// get other options (Details > General)OTHER_OPTIONS optsOther = iStEC3case.moGetOtherOptions();// get national annex (e.g. DIN, CEN, ...)NATIONAL_ANNEX natAn = iStEC3case.moGetNationalAnnex();// get interface for national annex detailsINationalAnnex iNatAn = iStEC3case.moGetNationalAnnexOptions();// get base data for national annexNATIONAL_ANNEX_OPTIONS_BASE natAnBase = iNatAn.moGetBaseOptions();// get data for general method from national annexNATIONAL_ANNEX_OPTIONS_GM natAnGM = iNatAn.moGetGMOptions();// get data for lateral-torsional buckling from national annexNATIONAL_ANNEX_OPTIONS_LTB natAnLTB = iNatAn.moGetLTBOptions();// get data for stainless steel from national annexNATIONAL_ANNEX_OPTIONS_STEEL natAnSTEEL = iNatAn.moGetSteelOptions();
The corresponding elements in the parameter dialog box of the add-on module are shown in Figure 02.
According to DIN EN 1993‑1‑1:2010‑12 , Annex BB.1.1, the buckling length may be used in the individual bracing under certain conditions. This means that in this case, the individual members, not a set of members, can be applied with the effective length factors specified in the standard.
Since this approach only considers the local failure, it is necessary to analyze the global failure of the entire structure. For this design, the set of members must have the corresponding imperfection. Under certain conditions, the design can be performed on single members, depending on the model (for example, a tower), or the set of members must be analyzed for a failure from the plane (the truss), as in the attached example.
StandardID and AnnexID can be easily displayed at any time by using the following macro:
You can find this macro in the archive of the product website (see Links).
Here is an overview of the current attachments:
StandardID AnnexID Name
DIN 0 Germany
ÖNORM 1 Austria
CSN 2 Czech Republic
STN 3 Slovakia
PN 4 Poland
SIST 5 Slovenia
DK 6 Denmark
UNI 7 Italy
NEN 8 Netherlands
SFS 9 Finland
SS 10 Sweden
NF 11 France
BS 12 United Kingdom
CEN 13 European Union
BDS 14 Bulgaria
CYS 15 Cyprus
LST 16 Lithuania
SR 17 Romania
SS 18 Singapore
NBN 19 Belgium
NP 20 Portugal
UNE 21 Spain
MAL 22 Malaysia
NS 23 Norway
LU 24 Luxembourg
ELOT 25 Greece
Any SHAPE‑THIN cross-section can be designed as follows:
- Stability and stress analysis with the RF‑/STEEL EC3 add-on module and the RF‑/STEEL Warping Torsion module extension, see Figure 01
- Generating surfaces from the cross-section (possible in RFEM only, see Figure 02), and a new definition of support and stress analysis of the newly created surfaces with RF‑STEEL Surfaces, if necessary, see Figure 03; under certain circumstances, a stability analysis with RF‑STABILITY for the surface model is reasonable, see Figure 04.
Yes, this setting can be made in Window "1.5 - Effective Lengths." Deactivate "Buckling Possible" or "Lateral-Torsional and Torsional-Flexural Buckling Possible", see the figure.
Please check the definition of the support of any intermediate nodes in Window "1.4 Intermediate Lateral Supports" or Window "1.7 Nodal Supports" in the add-on module, see Figure 01.
Since the module has its own solver, the support conditions are not automatically imported from RFEM/RSTAB, but must be defined manually.
The "RF‑/STEEL Cold-Formed Sections" add-on module allows you to design cold-formed L‑sections, Z‑sections, C‑sections, channels, top‑hat sections, and CL‑sections from the cross-section library.Furthermore, it is also possible to design general cold-formed (not perforated) SHAPE‑THIN 9 cross-sections.
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. ”