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Frequently Asked Questions (FAQ)
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AnswerIn order for smoothing ranges to be considered in the design in RF-STEEL Surfaces, they must always be activated in the detail settings of the add-on module. See Figure 01 with the detail settings in RF-STEEL Surfaces.
AnswerYou will find an option in the "Settings" of the add-on module (see picture 01).
Only the default setting of 1 load increment can be set when a complex nonlinear material model is defined. The reason for this is because the program cannot determine the correct material stiffness for each incremental loading amount. The exact maximum load needs to be applied to the structure in order to determine the state of the material's stress/strain diagram.Figure 01 - Material Model - Nonlinear material definedThis setting can be found and changed under "Calculation Parameters" as well as under the "Calculation Parameters" in the load cases and combinations dialog box.
AnswerIn the RF-/STEEL add-on module, an equivalent stress design is performed according to von Mises. An elastic stress design (EL-EL) is to be made. In RF-/STEEL EC3, a classification is carried out before the design. If the cross-section is classified as class 1 or class 2, the design is performed against plastic limit internal forces. An EL-PL design is performed. If you do not want to use the plastic load reserves, you can switch the design to EL-EL in the details of the RF-/STEEL EC3 add-on module. The results are then comparable with RF-/STEEL.
Most likely, the error is in the selection of the cross section:
For a steel design, a thin-walled flat steel cross-section should be selected instead of a rectangular solid cross-section, see Figure 1.
The reason for the high shear stress of a solid cross-section is caused by the existing stress points of the cross-section or by the corresponding thickness of this stress point.
In the case of a thin-walled flat steel cross-section, there are four stress points at the corner points of the cross-section with the corresponding thickness t = 10 mm, see Figure 2.
For a solid cross-section, however, there is another stress point in the center, where the maximum of height h or width b is assumed as the thickness t for this cross-section type. In this case, the width b is 200 mm, see Figure 3.
This results in a small torsional section modulus Wt and a correspondingly high shear stress.
Therefore, the solution is, as described above, to select flat steel within the main program.
AnswerIn SHAPE-MASSIVE, the reinforced concrete design has to be activated in the General Data section. As soon as the design is active, it is possible to set the design accordingly in a separate tab (Figure 01).There are three types for the design:Strain-Stress Distribution (Example 01):It is possible to determine an available design ratio by specifying the internal forcesExisting Safety (Example 02):There is determined a state of fracture (ratio = 100%) and a safety in relation to it.Design (Example 03):By specifying a maximum and minimum diameter or a minimum and a maximum reinforcement, it is possible to increase the reinforcement within the design.Irrespective of which of the three methods is used, it is necessary to specify the position of the reinforcement and an acting internal force (Figure 02).
AnswerBoth RFEM and RSTAB present a suitable solution. Numerous European and international standards, as well as various add-on modules, are available for both programs, which will facilitate the daily work in steel structures.
Basic programs RFEM or RSTABThe basic programs RFEM or RSTAB define structures, materials, and actions. In addition to creating spatial frame structures, for example, halls, RFEM also provides plate, pane, and shell structures, making it a more diverse option. It pays off if it is necessary to carry out design also in other areas, such as solid construction.
- EN 1993-1-1 (Eurocode 3),
- AISC according to ANSI/AISC 360 (US Standard),
- SIA according to SIA 263:2013 (Swiss Standard),
- IS according to IS 800:2007 (Indian Standard),
- BS according to BS 5950-1:2000 (British Standard) or BS EN 1993-1-1 (British Annex),
- GB according to GB 50017-2003 (Chinese Standard),
- CSA according to CSA S16-09 and CSA S16-14 (Canadian Standard),
- AS according to AS 4100-1998 + Annex 1 - 1999 (Australian Standard),
- NTC-DF according to NTC-RCDF (2004) (Mexican Standard),
- SP according to SP 16.13330.2011 (Russian Standard),
- SANS according to SANS 10162-1:2011 (South African Standard),
- NBR according to ABNT NBR 8800:2008 (Brazilian Standard),
- HK according to the standard for steel structures 2011 (Buildings Department - Hong Kong)
- RF-/STEEL - General Stress Designs
Add-on modules for structural steelwork
The functionality of the basic programs is supplemented by add-on modules. With RF-/STEEL EC3, for example, it is possible to perform the design for the structure according to Eurocode 3. The add-on module RF-STEEL Warping Torsion supplements this design according to Eurocode 3 with torsional buckling analysis having up to 7 degrees of freedom, provided it doesn´t refer to a standard case of EC3.
Other more specialized applications such as the plastic design, the stability analysis according to the eigenvalue method or the generation of geometric equivalent imperfections and pre-deformed equivalent models are available. Single modules such as PLATE-BUCKLING provide you with support when designing rigid or stiffened plates. With the SHAPE-THIN add-on module, it is possible to create any thin-walled cross-sections. The cross-section properties are determined and stress analyzes or plastic designs can thereby be performed.
The hinged or rigid connections can be designed by means of the RF-JOINTS add-on modules.
The stand-alone application CRANWAY is available for the design of craneways.
If earthquake calculations or vibration analyzes are necessary for the building, the RF-/DYNAM Pro add-on modules provide suitable tools for determining natural frequencies and shapes, analysis of forced vibrations, generation of equivalent loads, or for the nonlinear time history analysis.
In case of having any further questions about the Dlubal software, contact the sales department, please.
AnswerIn the general printout report selection, it is possible to define the load cases to be displayed, however, only for result types. Sometimes, however, it makes sense to differentiate this setting depending on the result type (for example, support forces of all load cases, internal forces should only be output by the governing load cases).On the one hand, this can be set with the special selection per result type (right-click the corresponding entry in the navigation tree).On the other hand, all load cases can remain selected in the general selection, and all unnecessary load case results are then removed manually from the navigation tree.This manual selection can be overwritten in the global settings. The corresponding option "Overwrite Individual Settings" appears here.
AnswerIf stiffeners are welded into the crane runway, the corresponding notch category according to EN 1993-1-9, Table 8.4, detail 7 has to be considered for the fatigue design. This is implemented in CRANEWAY by creating additional stress points at the connection point of the stiffeners to the section. They can be adjusted manually in the settings for the detail categories depending on the geometry of the stiffener.During the fatigue design of the craneway girder, the design of the axial stress range is additionally performed in the newly created stress points for the x-locations on which a stiffener is provided.
Cross-sections assigned to class 1 or 2 are designed plastically by RF-/STEEL EC3 by default. In order to be able to compare the results with RF-/STEEL, please activate the elastic design of class 1 and 2 cross-sections (Figure 2) in the Details of RF-/STEEL EC3.
Please also check whether the partial safety factors γ for the resistances of the cross-sections are defined identically in both add-on modules (Figure 3 and 4).
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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.
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