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Frequently Asked Questions (FAQ)
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In the main program RFEM / RSTAB, a member rotation of 90 ° is first required so that the lamellas of the glued-laminated beam are upright, see Figure 1.
To also consider the upright 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.
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.
In this case, start the project manager from the respective program (RFEM, RSTAB ...). Thus, if the project manager is started directly from RFEM, only RFEM files are displayed by default, see Figure 1.
The definition of slippage is recommended here. To do this, you have to set the partial effect in the 'Non-linearity' edit dialog box of the 'Edit Nodal Support' dialog box. In the 'Non-linearity - Partial Effect' dialog box, it is now possible to define a slippage in the respective area. The adjoining diagram is used for the check, see Figure 1.
To ensure that the floor rests only on the downstand beam in this situation (Figure 1), it is recommended to model a minimum opening within the floor surface, see Figure 2.
In order to keep the members or the lines of the members integrated into the surface, the'Connect Lines/Members' function has to be subsequently applied to the entire model one time. Thus, it is ensured that the floor slab continues to rest on the downstand beams.
In this case, the slab should rest on the downstand beam without any bond (see Figure 1).
First, assign the member type 'Beam' to the downstand beam because the rib is not effective here due to the missing joint.
To implement the non-linearity 'Only Transfer of Compression Forces in Z-Direction', you can use the 'Line Release' function. In this case, all forces and moments must be activated, that is, released, within the 'New Line Release Type' dialog box. Moreover, for uz, the non-linearity "Fixed if vz Is Positive" must be set, see Figure 2.
The line of the member within the corresponding area should be selected as a line to be released, and the corresponding surface like a released object.
The term "shear panel" indicates that the translational spring, which is created along the beam length by means of the shear panel type including the corresponding parameters, is smoothed, see Figure 1.
This is also the case for the shear panel type "Bracing", so that the mode shape always appears to be arbitrary at this location, see Figure 2.
In order to obtain accurate results, it is recommended to manually define a lateral support by means of a nodal support according to the general method (Figure 3) or to define the effective lengths according to the equivalent member method, including intermediate restraints, if necessary. Finally, a eigenvector with visible lateral restraint in the mid-span is created (Figure 4).
If the result beam is defined correctly, there may be a coarse FE mesh in the door lintel area, which leads to rough inaccuracies in the results (in this case, shear forces, see Figure 1).
It is recommended to create about ten finite elements above the height of the door opening. For example, if the height above the door opening is 0.5 m, a target FE mesh width of 0.05 m is adequate in this area so that the desired results are achieved (see Figure 2: Shear forces).
The settings are made globally (Menu → Calculation → FE Mesh Settings) or by using a local FE mesh refinement.
To prevent the error message (Figure 1) from appearing and the calculation to be started, it is necessary to assign a material to the corresponding point elements as follows:
- Right-click the entire cross-section: 'Reduce Cross-Section into Elements', Figure 2
- Selection of the corresponding elements or all point elements with the status ‘Insert’ by using the Views navigator, because it is only possible to define a material for them (in contrast to point elements with the ‘Remove’ status)
- Assign the corresponding material and confirm with OK, Figure 3
- Deactivation of visibility
- Select all elements and right-click one of the selected elements: 'Create Cross-Section from Selected Elements', Figure 4
If the results are not displayed exponentially (Figure 1) but as integers, the number of decimal places must be minimized, see Figure 2: Menu 'Options', 'Units and Decimal Places'.
Another option would be to change the unit from, for example, 'mm' to 'cm'.
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