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Frequently Asked Questions (FAQ)
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AnswerTo enter a taper on a beam, it is necessary to select the Layout dialog section. A taper can be modeled either on the bottom side or on the top side of the beam.The plate thicknesses, as well as the height of the taper, are defined by selecting a tapered cross-section, since, for example, repeatedly cut rolled cross-sections are used. If any plates are used, a parametric T-section can be selected. The length of the taper, as well as the material, are entered in the same dialog section. The weld thicknesses for connecting the taper to the beam can be defined in the Welds dialog section.If a tapered member is already used as a beam (entered in the 'Nodes and Members via Different Cross-Sections and Lengths' section), it is not possible to model an additional taper.
AnswerIn addition to geometry input errors, the cause is usually the different calculation principles of both modules.The design of an end plate joint with the RF-/JOINTS Steel - DSTV add-on module is carried out by comparing the saved ultimate load capacities with the design internal forces. The underlying load capacities are taken from the current DSTV guidelines.When using the RF-/JOINTS Steel - Rigid add-on module, the capacities of the connections are calculated according to DIN EN 1993-1-8 by means of the component method. Thus the results can be directly influenced by the used settings.By default, an elastic distribution of bolt forces is used as a basis. By selecting a plastic force distribution in the connection, you can activate additional load capacities. They are already included in the limit load capacities according to the DSTV-guideline.Therefore, to obtain comparable results between both add-on modules, a plastic distribution of forces must be applied for the calculation. In addition, it is important to ensure a correct modeling of the connection geometry.
If the flanges are not continuous and the diagonals are fastened to the flanges, it may be necessary to insert an intermediate member.
Figure 1 shows a system where the flange is not continuous but the diagonals are rigidly connected to the flange. To transfer the diagonal moments to the flange, the diagonal must arrive in the flange before the impact, otherwise the moment of the diagonal will be transferred to the opposite member (see Figure 2).
If the diagonals are also connected by hinges, you can do without the intermediate member. Please note that at least one member is not hinged so that the connection node can not rotate freely (see Figure 3).
If a vertical is used, it must either be connected to one of the two flanges or between both flanges. In both cases, the model from Figure 1 is suitable and has to be modified accordingly. Figure 4 shows the model with a vertical between the flanges and Figure 5 shows the variant with the vertical on the right flange.
AnswerThis message means that a particular cross-section cannot be used for some types of Sikla connections. Some cross-sections can be used as a supporting element in a particular connection, but not as an attached beam.
A mortar joint is applied when the bricks of a wall are not laid on one mortar strip but on two. In this case, the mortar has to be applied to the outer edges of the support surfaces of the bricks. By using a mortar joint, it is necessary to consider restrictions in the ultimate limit state, because unfavorable stress gradients occur in the wall.
The application of the mortar joint is governed by the current version of the National Annex in each European country. In the German National Annex, the construction of masonry by a mortar joint is not allowed. In Germany, the interstices of support have to be mortared over the entire surface each time.
AnswerFor rod end joints where the reference system is related to the local rod axes, the joint is placed directly on the rod end or rod end. If the joint is to act directly at the node, the reference system must be related to the global axis system.
AnswerThe area on the right in Fig. 1 therefore receives a moment in the area of the support because this surface is rigidly connected to the support (the surface itself does not have a line joint). If one wants to exclude this moment, one would therefore have to create an additional line joint for the right-hand surface or provide the support with a rod end joint.
AnswerIn RSTAB there is also the possibility to determine plastic internal forces. To do this, one must select a plastic joint as non-linearity via the rod properties (see Figure 1). However, this does not involve interaction of the plastic forces. Another possibility is to directly set joints with nonlinear properties. However, with this method you have to estimate in advance where these joints form.In RFEM it is possible to select a corresponding material model (see Figure 2).
AnswerTo perform a design for several connection nodes, the following points must match:
Deviations in the connection nodes may be as follows:
- the different connection nodes must use the same geometry type, for example, the knee crack
- The beam and the column (s) of the different connection nodes must be the same length
- the material of the column cross-sections and the cross-section material must match respectively
- The horizontal beam and the column (s) of the different connection nodes must have the same cross-sections
- Beams of different connection nodes must have the same inclination
- You can use different cross-section and material numbers
- the number of connected elements, such as tension diagonals, may deviate
- Different types of hinges can be used
AnswerThe auxiliary values λ1 and λ2 are required to determine the effective lengths.
These two values are used to determine an α value from Figure 6.19 of EN 1993-1-8, which is then used to calculate the effective lengths (for non-circular flow lines) of the T-stub flanges.
The maximum value for λ1 is 0.9 and the maximum value for λ2 is 1.4 -> see Figure 6.11 of EN 1993-1-8
Based on your geometry, however, the result is, for example, a λ2 of> 1.4 for the end plate
α can only be calculated with the maximum value of 1.4.
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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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