Question:
How can I model double members in RFEM 6, such as those in a telescopic connection?
Answer:
The interlocking components of a telescopic boom of a construction machine, for example, transport their forces mechanically between the components.
This special force transfer can be solved in RFEM 6 as follows:
A characteristic plug connection like the one shown in the sketch consists of four members. Two members (Members 2 and 4) lie on top of each other in the overlap area.
You can create superimposed members using line releases. To do this, define a line release on Line 2 that releases Member 2. The line release creates the released Line 4, with the corresponding released Nodes 4 and 5. However, the members should be connected at their nodes, so Line 4 should be defined by the same Nodes 2 and 3 as Line 2. The generation of the released Nodes 4 and 5 is therefore prevented by specifying the definition nodes 2 and 3.
The properties of the line release are described by hinges in the line release type. The members should be completely decoupled from each other along their length, so that all degrees of freedom are released.
Member 4 can now be defined on Line 2.
To ensure that the force is transferred correctly to the structure, it is necessary to arrange specific member hinges.
Here, a moment hinge (scissor hinge) on members 1 and 2 at node 2 and on members 4 and 3 at node 3 is intended to ensure that the bending moment loading between the red continuous members (members 1 and 2) and the green continuous members (members 3 and 4) is transferred to nodes 2 and 3 via a pair of forces.
An axial force hinge (scissor hinge) on members 4 and 3 at node 3 is intended to ensure that an axial force loading is only transferred between the green and red continuous members at the planned fixation at node 2.