Further Information

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• How can you realize a pure compression connection between two surfaces so that one wall is similar to another?

You can realize such a connection with a line release. Figure 1 shows an example model where wall 1 should transfer only compressive forces to wall 2.

First, the dialog box for creating a line release is opened (fig. 2). In the dialog box (Fig. 3) Now select the lines for release and type. The Type must also be created. The coordinate system of the line specifies the direction so that "If vy positive" must be selected as release (Fig. 4).

Figure 5 and 6 show in two load cases, how the line release works.

• How can I display the result diagram of a line release or a line hinge?

New FAQ 003039 EN-US Results RFEM

To display the result distribution of a line release or a line hinge, right-click the relevant line release or line hinge. Then, select "Result Diagrams" in the shortcut menu (see Figure 1).
• What is set with the definition nodes in the dialog of the line release?

A line release automatically generates a new line with new nodes. If you want to use your own nodes as end nodes for the new line, you can specify them here.

• How can surfaces on other surfaces or bars be hinged / compliant?

Basically, elements in RFEM are rigidly connected. To solve this problem, two elements are suitable in RFEM. The line joints and the line releases. The difference is explained in the link below.
• After the calculation, I get an indication of a large deformation. Why can not I find this deformation in the output?

New FAQ 002912 EN-US Results RFEM

If you define line loads on a line that is decoupled from the overall system, that line becomes compliant. The program checks this incorrect entry and gives a hint (Fig. 1). However, there are structures where this line is kept at a different point. In this case, the program continues to calculate after the user has confirmed the note. However, since the deformation for such a decoupled line becomes very large, it is not displayed in the graphic output.

We generally recommend not to load lines that are decoupled via a line release or line joint.

• Can I enter maximum internal forces for line releases in RF limits?

No, that's not possible yet. However, there is also the possibility of evaluating the line release directly via RFEM. Although no utilization is indicated with this method, it is suitable for assessing the transmitted forces.

The resultants for the results of line joints and line releases can be displayed via the results navigator under the entry "Approvals". In this case, a distance-related evaluation (see Fig. 01) or the consideration of the total value (see Fig. 02) is possible.
• What is the sign definition for the nonlinearity of a line release?

The direction determination is basically determined by the line release axis system and the location of the cut-out object. The line-sharing axis system display can be viewed in the Project Navigator - Show under Model -> Line enables are activated (see Figure 1).
Determining the direction for the nonlinearity determination is important how the released object moves relative to the line release axis system from the original element.
In Fig. 2, the area 2 with the line release u z fixed if v z is defined as a negative object. The load shown at 1 and 2 would move the released surface 2 against the z-axis of the line release axis system. The line release would therefore not be effective at these loads, ie the surfaces 1 and 2 would be firmly connected.
• What are the differences between a line gel and a line release?

Line joint:

Line joints control the connections between surfaces. Thus, complete decoupling of surfaces or yielding couplings via linear springs can be considered.
The line joint functions to reduce the stiffness in the adjacent first row of elements of the associated surface according to the degrees of freedom chosen. In concrete construction can with a line joint z. B. an assembly joint can be defined. In timber construction, modeling with line hinges is necessary due to the very limited rotation transmission of forces.

Line release:

With line sharing, elements connected to a line (bars, areas, and volumes) can be decoupled from each other. A new line will be generated in the same place, transmitting only the locked degrees of freedom. In contrast, non-linear effects can be taken into account for a line joint (see Figure 2).

First, the line release type must be created. This defines the open degrees of freedom or spring constant and optionally nonlinearities. Subsequently, the line release for bars, areas and volumes can be made on individual lines. The axis system of the release can also be manipulated in the same dialog box.

If line joints have already been used in a position, they can be quickly converted to a line release (see Figure 3). This makes it very easy to consider nonlinear effects in the system.
• By using line releases the software tells me the Release definition is not unique. What does that mean?

Line releases are defined by an additional line automatically generated by the software. The theoretical background of line releases is a also described in this article.

For a detailed explanation of this alert a model is attached to this FAQ.

In this model for the line release 3 a definition node has to be defined. Because if the software would generate an additional virtuall node surface 2 would be destroyed.
Imagine the following sceanrio.
You have 4 surfaces 1,2,10,14 (picture 2).
If you define a line release to line 3 it`ll look like shown in picture 3.
As the surface 2 would be destroyed by that as line 6 is the same for surface 2 and 14 the line 6 has to start at the node 3 and at the generated node (picture 4).
This is where you need the definition node and in case it is not defined the software gives the alert.

• Is it possible to model a semi-rigid composite beam with a line release using members in RFEM?

FAQ 002560 EN-US Modeling | Structure RFEM

Yes, it is possible. For this, you should ensure that one beam is only modelled first, whose lines are released with a line release. You will then add another member to the automatically generated copies of the lines.

For split beams, make sure that both members connected on the nodes are released in the table of line releases. Under Downloads below, you can find an example of a composite plate made of timber and concrete from [1] as a calculated model and the workflow as a video.

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