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Frequently Asked Questions (FAQ)
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AnswerWith the model check, members that cross each other but do not have a common node at the point of intersection can be found (see Figure 1). To check the model, select Tools -> Model check -> Opening or closing intersecting members.
The results are shown in the "Groups of Crossing Not Connected Members" dialog section. The crossing members are listed in groups; the current group is represented by a
The "What is to be done with" dialog section controls how the crossing members are handled. The "Connect members" option is suitable for actual transfer options for internal forces, but not for For example, for usual diagonal crossings with tension members.
Alternatively, it is also possible to use the model check to display the member pairs as an Excel list or to create visibilities. The visibilities created in this way can be quickly used to find and delete relevant members in the model.
Finite elements with plastic material are divided into 10 layers. First, a normal elastic analysis is performed in the first iteration. Then, the stress in each element is calculated according to the set strength hypothesis in each individual layer. If the limit stress in one of the layers is exceeded, the stiffness of this layer is reduced. Based on the reduced stiffnesses of the 10 layers, an overall stiffness is determined for each element. With this new stiffness, we start a new calculation iteration.
Iterates until the changes are only small.
The total stress is converted into the stresses of the individual layers by means of the laminate theory. This theory is also applied for the conversion between the stiffnesses of the layers and the total stiffness.
4 different strength models can be used as the limit stress:
- Shape Change Energy Hypothesis (von Mises-tension)
- Shear stress hypothesis (Tresca stress)
- Failure hypothesis according to Drucker-Prager
- Failure hypothesis after Mohr-Coloumb
The choice of the failure hypothesis is shown in Figure 1.
The von Mises hypothesis is preset because it is the most frequently used strength theory.
AnswerThe reason for this message is that you are in viewer mode. When installing RFEM or RSTAB, a viewer version is automatically installed in addition to the normal version. This will appear as an additional icon on the desktop. In this mode, files with results can be opened, but no changes can be made.
I get the following error message. Error no. 30426 - Error no. 1 model is not stored!What is the problem?
AnswerPlease define bearings in the model, which contain the loads, otherwise no calculation is possible. In RSTAB you can, for example, provide node storage, in RFEM node, line and area storage.
AnswerFor the design of steel surfaces please use the module of the same name RF-STEEL Surfaces. If you also want to consider local denting, then the additional modules RF-STABIL (to determine the bulge and branching loads) and RF-IMP (to determine the imperfection figure, based on the bulge pattern) are also recommended.
AnswerIndependent submodels are not interconnected and are considered as separate submodels in the calculation. They are thus independent models without influencing each other (see Figure 2).It is recommended to edit submodels separately as individual files. Then a stability analysis with RSKNICK is possible.Otherwise, the partial models must be connected to each other. In this case, it should be taken into consideration that the static systems of the submodels should be retained when the submodels merge into an overall model (see Figure 3).The feature "Independent Systems" is helpful in detecting partial models. This finds all independent systems and lists them as groups (see Figure 4).One finds this function under Extras -> Model control -> Independent systems.
AnswerThe add-on module RF-MAT NL is already integrated in RFEM 5. It is assumed that the following material models can be used:Isotropic Plastic 1DIsotropic Plastic 2D/3DIsotropic Nonlinear Elastic 1DIsotropic Nonlinear Elastic 2D/3DOrthotropic plastic 2DOrthotropic 3D plasticIsotropic Masonry 2DIsotropic damage 2D / 3D
AnswerThis depends on the choice of model type. In this case a flat system was chosen. Thus, only for this level, the relevant results are displayed because they are reduced because of the limited coordinates and degrees of freedom. If, on the other hand, a 3D system is selected as the model type, all stresses and internal forces are displayed.
AnswerFor some parameters, additional [Details] buttons are available in the display properties. You open a new dialog box where z. For example, you can scale the distance or size of the object to the dimensions of the entire model.
AnswerThere is no setting by program. It is usually sufficient to install the mouse driver of the manufacturer. Alternatively, you can rotate the model as described below:1. You can activate the command "Move view, Zoom [Shift], Rotate [Ctrl] or [Alt]". See Figure 1.When the command has been activated, you can hold down the left mouse button and click [Shift], [Ctrl] or [Alt] to change the view.2. To rotate the model, you can hold the left mouse button and hold down the mouse button (mouse wheel) while holding down the mouse button. We change the view when we move the mouse pointer.
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