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Frequently Asked Questions (FAQ)
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Similarly to surfaces, there are various smoothing options for displaying the results of support reactions. For a nonlinear support, you should always select the actual distribution to display the results. 
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In the "Edit Load Cases and Combinations" dialog box, you can specify in the bottom right of the "Combination Expressions" tab which method of analysis should be used as the basis for the generated load combinations. By default, the linear calculation according to the geometrically linear analysis is preset for load cases and the nonlinear calculation according to the secondorder analysis for load combinations.Thus, you can quickly determine whether the load case or the load combination is calculated according to the geometrically linear, secondorder, or large deformation analysis. The postcritical analysis option allows you to carry out the stability analysis according to the large deformation analysis with regard to the postcritical failure of the entire structure.In case the model includes cable members, the calculation according to the large deformation analysis is preset in all cases. 
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The zero coefficient of structural soil strength can be used for better convergence of deeper excavations or small loading. Damaged soil have no structural soil strength. Therefore, it better picture damaged subsoil in the upper layers with this function. The possible entry for the depth of the soil failure is from 0.0 m to 1.0 m. 
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In the case of cross laminated timber panels not glued to the narrow sides and a walllike structural behaviour, the torsion stress in the glued joints is often decisive. This design is performed according to the explanations in the literature reference below according to the following equation.$\eta_x=\frac{\tau_{tor,x}}{f_{v,tor}}+\frac{\tau_x+\tau_{xz}}{f_R}=\frac{\displaystyle\frac{3\ast n_{xy}}{b(n1)}}{f_{v,tor}}+\frac{{\displaystyle\frac{\frac{\partial n_x}{\partial x}}{n1}}+\tau_{xz}}{f_R}\leq1$Values: b board width
 n number of board layers
 n_{xy} shear in pane plane
 $\frac{\partial n_x}{\partial x}$ shear of board layers
 $\tau_{xz}$ shear in thickness direction
 f_{R} rolling shear strength
 f_{v,tor} torsional shear strength
For the ydirection, the design is analogous but with the values for the ydirection. 
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For the superstructures of the manufacturer Binderholz, as soon as the slabs are defined without glue at narrow sides and design of shear failure is calculated in the wall plane, the shear strengths are calculated according to the following equation.$f_{v,k}=\left\{\begin{array}{l}\begin{array}{c}3,5\\8,0\frac{D_{net}}D\\\end{array}\\2,5\frac{(n1)(a²+b²)}{6Db}\end{array}\right.$Values:D element thicknessD_{net} sum of longitudinal and transverse layer thicknesses in the elementn number of board layersa = b width of the boards in the longitudinal or transverse layersAll values in N/mm². For more detailed information, check the manufacturer's approval. 
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To correctly combine the planned prestress with the other load cases, define a suitable load case and apply a "pulling" strain load to the members concerned. The pulling strain load can be, for example:
 a negative temperature load T_{c} distributed uniformly over a cross‑section,
 a negative axial strain ε,
 a negative axial displacement Δl,
 a positive initial prestress V, or
 a positive final prestress V (in RFEM only).
The input by using the axial displacement is the most comprehensible input as you can directly measure the displacement at the turnbuckle of the tension member. 
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There is currently no direct way to determine the postcritical load. It is important that there are also several different states, and thus that there can be several local postcritical loads.
You can assign load increments to the structure and retroactively view the individual load increments, and thus find a load factor close to the postcritical failure (depending on the number of load increments).
In the attached model, 20 load increments and saving of the intermediate results have been set (Figure 01). Figure 02 shows Load Increment 10 as the last load increment before the postcritical failure, and Figure 03 shows the first load increment after the postcritical failure, whereby the deformation is significantly higher.

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When defining nonlinearities, such as support failure under tension, it may happen that some load cases cannot be calculated. If these are the loads that cannot exist without other stabilizing loads, the problem resolution is simple: You can set the load cases to "Not To Be Calculated." As a result, the load combinations are only considered in the "Calculate All" option of the calculation process. This is possible because some loads can never appear without a dead load, for example.In the attached example, it is clearly evident that the structural system would buckle in the Wind load case, and thus no convergence is found. In contrast to this, it is possible to calculate the load combination, where the dead load and the wind are combined without any problem because the dead load stabilizes the system. 
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In this case, it is recommended to use the definition of slippage. For this, select Partial Activity as a "Nonlinearity" in the "Edit Nodal Support" dialog box. In the "Nonlinearity  Partial Activity" dialog box, you can define the slippage in the respective zone. For checking purposes, there is a diagram, see Figure 01.

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A critical load factor specifies which factor can be used to increase the load until the structural system fails. If it is smaller than one, the calculation according to the secondorder analysis is usually unstable as the structural system is already subjected to the critical load. This factor is also referred to in standards. For example, Eurocode 3 specifies that the calculation according to the secondorder analysis is no longer necessary as of the critical load factor of 10.The critical load factor can be determined by using the RF‑STABILITY or RSBUCK addon module.
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First Steps
We provide hints and tips to help you get started with the main programs RFEM and RSTAB.
Wind Simulation & Wind Load Generation
With the standalone 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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