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Frequently Asked Questions (FAQ)
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AnswerIn this case, it is recommended to use the module extension RF‑/STEEL Warping Torsion:RF-/STEEL Warping Torsion is an extension of the RF-/STEEL EC3 and RF-/STEEL AISC add-on modules. It performs flexural-torsional (flexural-torsional) buckling analysis of members according to the second-order theory with seven degrees of freedom and application of imperfection with regard to mode shape.You can find more information under the links below this FAQ.
AnswerBoth RFEM and RSTAB provide a suitable solution. For both programs, there are numerous European and international standards as well as various add-on modules that facilitate your daily work in steel construction.
Main Programs RFEM or RSTABThe main programs RFEM or RSTAB are used to define structures, materials, and actions. In addition to the option to create spatial frame and truss structures, such as halls, RFEM also allows for plate, wall, and shell structures, and thus provides a more versatile option. It pays off if it is necessary to also carry out design 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 Code of Practice for the Structural Use of Steel 2011 (Buildings Department - Hong Kong)
- RF-/STEEL - General stress analysis of steel surfaces and members
Add-on Modules for Steel Structures
The add-on modules complement the functionality of the main programs. For example, RF‑/STEEL EC3, allows you to perform design of steel structures according to Eurocode 3. The RF‑STEEL Warping Torsion add-on module supplements the design according to Eurocode 3 with torsional buckling analysis with up to 7 degrees of freedom, provided it does not refer to a standard case of EC3.
Further specialized application areas, such as plastic design, a stability analysis according to the eigenvalue method, or the generation of geometric equivalent imperfections and pre-deformed equivalent models are available. Stand-alone modules, such as PLATE-BUCKLING, support your design of rigid or stiffened plates. The SHAPE-THIN program allows you to create any thin-walled cross-sections. Thus, the cross-section properties are determined and stress analyses or plastic designs can be performed.
You can design hinged or rigid connections by using the RF‑/JOINTS add-on modules.
The stand-alone program CRANWAY is available for the design of craneways.
If it is necessary to perform seismic analysis or vibration designs of a building, the RF‑/DYNAM Pro add-on modules provide special tools for determining natural frequencies and mode shapes, for an analysis of forced vibrations, a generation of equivalent loads, or for a nonlinear time history analysis.
If you have any question about the Dlubal Software programs, please do not hesitate to contact our sales department.
AnswerIn the case of long crane runways and many cranes, the large number of load combinations can lead to a long calculation time. The following settings affect the calculation time significantly:
Calculation Method for Determining Internal Forces
The fast calculation type may therefore be useful for preliminary design.
- Fast calculation (a calculation of all load combinations according to the linear static analysis, then a calculation of the governing load combinations according to the second-order torsional buckling analysis)
- Detailed calculation (a calculation of all load combinations according to the second-order torsional buckling analysis)
Maximum Target Length of Finite ElementsThe maximum length of the finite elements generated for the calculation according to the second-order torsional buckling analysis can be entered within the range of 100 mm to 2,500 mm. The calculation time can be increased significantly by the finer division of finite elements.Thus, you should select a reasonable length of the finite elements for an optimized calculation time, depending on the structural system. Usually, 8 elements for each girder span are enough to calculate the deformations with a deviation of less than 5% with regard to a precise solution.
Number of Load CombinationsYou can use a reasonable setting of the load increment to control the number of generated load combinations. When entering the load increment, the generated number of crane load positions and load combinations is already displayed in a preview. A small load increment may result in many load combinations that take more time in the calculation accordingly.
AnswerThe reason for this is that no results have been selected. As soon as you activate at least one check box that leads to results, the members will also be displayed.
AnswerThe load application point in the detail settings of RF‑/STEEL EC3 Warping Torsion only refers to the transverse loads.
AnswerThe axes, to which the support rotations and support eccentricities refer, are preset to the local member axes, which can be displayed with the button under the partial view. However, they can also be switched to the global axis system.
AnswerFor a stability analysis of any cross-section, the add-on modules RF‑/STEEL EC3 Warping Torsion (extension for RF‑/STEEL EC3) and RF‑/FE‑LTB (stand-alone module) are particularly suitable.By using the calculated critical buckling value, you can determine critical loads and perform the design according to the second-order analysis.
AnswerFor cross-section and stability analyses, Eurocode provides different partial safety factors. It is important to pay attention whether the stability analyses are performed by using the second-order analysis and applying imperfections as cross-section designs. In this case, it is necessary to reduce the resistance with γM1.
AnswerVertical wheel loadsQ C (share due to crane own weight)Q H (share due to lifting load)Horizontal wheel loads
H T (proportion as a result of starting / braking the crane bridge)
H S (proportion of skew forces as a result of starting / braking a crane)
H T3 (proportion as a result of approaching / braking trolley or hoist)longitudinal loads
H L (proportion as a result of starting / braking a crane)In addition, if a skew force (S) or a buffer force (H B ) is effective, it can be given below the table.There is already an interesting webinar on the subject " Dimensioning of crane runways according to Eurocode 3 " on our homepage.
AnswerLike the internal forces, the support forces from the load cases are combined taking into account the dynamic coefficients. For this purpose, the support forces (except for LC1 and LC2) are multiplied by the ratio of the dynamic coefficient girder to the dynamic coefficient support and added according to the CO criterion, since the wheel loads from LF3 already include the dynamic coefficient for the beam.When Only max/min option is selected, only the extreme values of the support forces are output for the corresponding directions, i.e. the characteristic support forces are multiplied by the corresponding dynamic coefficient for supports (see Figure).We already have an interesting webinar about "Design of Craneway Girders According to Eurocode 3" on our homepage.
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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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