Creating moving loads in RF-MOVE Surfaces
Tips & Tricks
RF-MOVE Surfaces makes it easier to create load cases from different positions of moving loads. Based on the moving load's load positions, RFEM generates separate load cases for RFEM. Optionally, an enveloping result combination of all load positions is created.
You can open the add-on module via the RFEM menu item Add-on Modules → Other → RF-MOVE Surfaces. Alternatively, you can open the Project Navigator-Data by clicking the Add-on Modules → RF-MOVE Surfaces entry.
First, you specify the surfaces on which the moving loads are to be generated.
If there are already moving loads in the structure, you have to make further entries in the "Export type" section. If this is not the case, this section is grayed out, as in our case.
The Result Combination check box of the "Envelope" type then allows you to generate a result combination from the load cases of the moving loads. The variable option is selected as the action criterion of the load cases.
The "Influence Lines/Influence Surfaces" section allows you to consider influence lines and surfaces that have been determined with the RF -INFLUENCE add -on module. The amount of data can be reduced as only unfavorable load cases are generated. In the present example, this check box is not activated.
Next, you define the path that the moving loads should cover. For this, a set of lines must be created. It is recommended to define the "lane" in the RFEM model in advance.
In the "List of lines/set of lines No." you can enter the numbers of the lines that represent "guide lines" for the moving load manually. The order of the numbers determines the direction of travel.
The lines can of course also be selected graphically in the work window. Also, make sure to click the lines in the correct order.
The "Parameters" section manages global specifications for the load case generation.
The increment controls the equal intervals at which the loads move over the surfaces. The smaller the moving step is, the more load cases are created. Furthermore, it is possible to apply an offset and/or a buffer.
This window "Moving Loads" manages the parameters of the movable loads. Different loads can be combined in a load model. The module assigns defined load models to the sets of lines and creates individual load cases based on this data.
Then, you can define the load as a force or a moment, and select the load distribution. There are several options available.
In this example, the load distribution axis - rectangular surfaces is selected. This has the advantage that the load is distributed as a block load pair on two surface loads at a distance of the track width and thus, in contrast to a single load, singularities can be avoided.
Since the composition of the movable loads is usually associated with effort, they can be saved in the load model library so that they can also be used for other projects. In addition, a large number of other load models are already stored in the database.
The last window "Movement Schemes" connects the geometry input of the sets of lines with the loading input of the moving loads. Thus, the window defines which load set is moving on which set of lines.
In most cases, a single movement scheme is sufficient, as in the example.
Set 1 is applied as the set of lines and load model 1 as the moving load. Imposed loads of category F are selected as the action category.
Generation and Results
The various load cases can be generated with a single mouse click on "Generate". At the end of the generation, the numbers of the created load cases and result combinations are displayed as a note, here 81 in number.
The RF-MOVE Surfaces add-on module does not display any result windows. The loads generated in the individual load cases can be checked as usual in the graphic, the editing dialog boxes or the "Loads" table below. They entered the corresponding tables as free concentrated loads, free line loads, or free polygon loads.
The module's data is not managed separately in the printout report. The generated load cases including loads are transferred to RFEM where they can be integrated into the documentation.
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Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements
Generation of load cases from moving loads for surfaces