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Frequently Asked Questions (FAQ)
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A taper describes a member or a surface with a variable cross-section. The cross-section type must be consistent, for example, I-shaped cross-sections at both member ends.
In our example, we have a member with a PRO cross-section and a QRO cross-section.
To create a tapered member here, you should use a parametric cross-section for the member start and end:
This allows you to calculate the tapered member.
An automatic increase of the reinforcement for the deformation analysis is not possible. As soon as the deformation calculation is based on the determination of the stiffness, it is not expedient to develop an algorithm that B. increases the reinforcement at the point of maximum deformation. Such a procedure would not result in the deformation being reduced.
Therefore, the reinforcement must be increased manually.
AnswerPlease check if the structure tears due to pure load. It is possible that the increase in deformations is mainly caused by creep and shrinkage, which are not active at time 0. In the nonlinear calculation, shrinkage is considered as a strain load, which can cause additional stresses.
In the wind profile, you always define the height ranges from z. B. 0 - 5 m, then 5 m - 10 m, etc. If your wind profile ends at 100 m, it is not cut off, but the value for 100 m is also applied for greater heights. If your wind tunnel is smaller than the stored profile, only the wind speeds up to this height are considered.
You can check this visually by displaying the velocity vectors and deactivating the display on a reduced area.
For a wind tunnel with a height of 50 m, you get the following result:
For a wind tunnel with a height of 150 m, you get the following result:
You can include the RSTAB printout report if you print it with a virtual PDF printer, for example PDF24.
It is necessary to pay attention to the PDF created by RSTAB or RFEM for "optimizing the web". Then it can be easily inserted into scientific programs.
AnswerBoth RFEM and RSTAB can be the solution . For both programs, there are standards available with which the aluminium and light-weight structures can be calculated and designed.
In addition to Eurocode 9 with numerous National Annexes, the American standard ADM 2020 is also available.
Further add-on modules for membrane and cable constructions complete the options.
Main Programs RFEM or RSTABThe main programs RFEM or RSTAB are used to define structures, materials, and actions.
If you also want to analyze membrane and cable structures, you need RFEM . When it comes to pure beam structures, the purchase of RSTAB is sufficient. In any case, RFEM is the more diverse option because it can be equipped and extended with the corresponding add-on modules for all materials and designs.
- RF-/ALUMINUM according to Eurocode 9 (EN 1991-1-1: 2007)
- RF-/ALUMINUM ADM according to ADM 2020 (US standard)
- RWIND Simulation
Complex analysis of any structures in the digital wind tunnel with transfer of load cases to RFEM or RSTAB for further processing.
Dynamic analysisIf 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.
- Building Information Modeling (BIM)
An extensive collection of interfaces allows data exchange with other programs.
Temperature-dependent stress-strain properties of an elastic isotropic material can be defined in a diagram or imported from [Excel]. These properties are considered for member and surface elements subjected to thermal load (changes or differences in temperature).
The Reference temperature defines stiffnesses for the members or surfaces that have no temperature loads. For example, if a reference temperature of 300 °C is set, the reduced elastic modulus of this point of the temperature curve is applied to all members and surfaces.
The Options dialog section allows you to control if the Poisson's ratios that are applied to the complete temperature diagram are identical. Clear the check box to access the Poisson's Ratio table column for individual entries.
You have to select and define the Temperature/Modulus diagram by your own.
The setting for the deformation coefficient kdef can already be made in the model data. There, you can specify the deformation coefficient manually or select it based on the service class.
The deformationfactor k def is considered in the load combinations for serviceability in the program (similar to DIN EN 1995-1-1, 2.2.3).
For the design of mixed structures made of timber materials, see FAQ 4325 .
In the FAQ downloads you'll find a sample code how to set NURBS surfaces. The knot vector KnotsX, KnotsY determines how the control points affect the NURBS curve. The number of knots is equal to the number of nodes plus order.
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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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