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Frequently Asked Questions (FAQ)
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Basically, all cross-sections of the solid and hybrid cross-section groups can be designed in the RF-/TIMBER Pro program. In Figure 01, they are shown on the right.
For more complex unsymmetric cross-section shapes, it may be necessary to adjust the allowable principal axis angle in the add-on module on a user-defined basis (see Figure 02).
Yes, that is possible.First, RF-STABILITY (or RSBUCK in RSTAB 8) can be used to determine the effective lengths for a particular structure and loading.They can then be imported in the 'Effective Lengths' of the RF-/TIMBER Pro dialog box.
In the main program RFEM/RSTAB, a member rotation of 90° is first required so that the lamellae of the glued-laminated beam are arranged on edge, see Figure 1.
To also consider the on-edge position of the beam in the design in the RF-/TIMBER Pro add-on module, increase the resistance for edgewise bending within the parameters set in the National Annex in the tab 'Other Settings 2/2', see Figure 2.
The setting in Figure 01 only controls the influence on the design side. After having activated this function, the buckling designs in the "Effective Lengths" window are deactivated. Thus, only a lateral-torsional buckling analysis is performed.
In order to calculate with the design values of the stiffnesses, they have to be reduced by the partial safety factor according to . To do this, select the highlighted option in the calculation parameters (see Figure 02).
In case of having used the automatic combinatorics for the standard EN 1990 + EN 1995, this setting is - according to the second-order analysis - automatically activated for the ULS in respective combinations. This option is automatically deactivated for combinations with SLS as well as for combinations that are generated according to the linear static analysis. However, the automatic assignment is only carried out by means of the analysis type in the 'Combination Expressions' window (see Figure 03).
If you want to calculate the component stiffnesses with the 5% quantile value of the stiffness parameters divided by the partial safety factor, you have to additionally activate the 'Modify Stiffnesses' function in the calculation parameters and modify the stiffnesses manually.
AnswerFor many users, the very realistic display of a building in construction programs arouses the wish to carry out the structural analysis of this building with the same complex spatial model.Again and again, the design of log cabins is approached to us. Unfortunately, this attractive construction method is relatively complex for three-dimensional analysis. The dimensioning results in some critical questions that cannot be answered.
Furthermore, log houses are common for houses with a maximum of 2 full floors because of their high placement of more than 15 cm per storey. Thus, the occurring forces are within a manageable framework and can be determined sufficiently precisely with the methods of the structural analysis for members in 2D structures. In RFEM/RSTAB, there is an option to define rounded bars in a tapered way for this purpose. Thus, the definition of 2D equivalent systems can be done much faster in RFEM/RSTAB.There is some information in the given literature source.
- Which sorting class is the timber subject to? In a log house, damp unsorted timber is often used.
- How is the contact between the timber types regulated? Diamond notch, connection with moving timbers etc.?
- Have mullions been installed? Which type of timber and how are they supported horizontally?
- Which dimensions does the timber have? In a log construction, a grown trunk can often be integrated. These trunks do not have uniform dimensions because nature cannot be put into a grid.
- How is it possible to consider contact between two layers of a timber?
AnswerIn general, all result combinations can be designed with the RF‑/TIMBER Pro program. However, there is the special feature in timber construction, that the governing load combination is not the combination with the largest internal forces due to the load duration class (LDC).In the case of the result combinations, it is necessary to distinguish between 4 basic types of combinations.
In this respect, there is a special feature of the combination from the RF‑/DYNAM Pro add‑on module. In this case, the results are constantly superimposed and additionally squared. However, these combinations are then comparable with the third combination mentioned above.Results used in TIMBER Pro for each result combination.
- Permanent and additive (+/-) superposition of all actions.
- Actions different in permanent or variable, but additive (+/-) superposition.
- All actions permanent, but superimposed with 'or'.
- All actions variable, but superimposed with 'or'.
- The maximum moment in the attached file is used. The 'Short' LDC is correctly taken into account.
- In a simple example, the moment is correctly taken into account. However, a support moment on the continuous beam can be taken into account incorrectly. The LDC in RC2 is considered as 'permanent' by default. Therefore, the design becomes very unefficient and must be changed in this case (see Figure 02). However, 'permanent' might be correct for the continuous beam mentioned above.
- In the case of RC3 and RC4, there is a pure result evaluation, which is possible in all design modules.
AnswerWhen selecting the standard SIA 265, RF-/TIMBER Pro can only use materials for the members to be designed, which are also allowed in the standard. You can easily find the allowable materials in the material library by using the filter of the standard.
AnswerYou can usually set the standard and the National Annex in the top right corner of an add‑on module (see Figure 01). In most cases, it is also possible to display the factors of the National Annex and edit them, if necessary (see Figure 02).
Yes, that is possible. However, it is very important to use the correct identical format and the assignment of the corresponding members in the Excel import. This works great if the lengths are first exported to EXCEL and then imported again. This is shown in the attached video.There are more ways to change the effective lengths via the RF-/COM add-on module. The mentioned modules are linked to this add-on module.
The stresses of hybrid cross-sections can be displayed as Stresses in RFEM (see Figure 01).
Moreover, with the RF-/TIMBER Pro add-on module, it is possible to display the stresses on the cross-section by x-element (see Figure 02). This option is available in the add-on module of both RFEM and RSTAB.
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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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