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FAQ 004223 | The load distribution in RFEM shows unstressed FE elements in the middle of the mode...

Video 01 - FAQ Explanatory Video

Figure 01 - Left: RFEM Model | Right: Wind Load Distribution on Individual FE Elements

Figure 02 - Left: Wind Pressure on Structure | Right: Simplified Model

Figure 03 - Setting Level of Detail in RWIND Simulation (Left) and in RFEM (Right)

Figure 04 - Model with Higher Level of Detail and its Results

18 November 2019

FAQ 004223 EN

Finite Element Analysis

The load distribution in RFEM shows unstressed FE elements in the middle of the model for loads of RWIND Simulation. What is the reason?

Answer

There is no load distribution displayed between the external facade elements at the example shown in Figure 01. Unstressed cells are not displayed according to the color scale during load distribution, but remain empty. Thus, the value on these elements is 0. This has the advantage that it is recognized immediately that the FE elements are not stressed.

Figure 01 - Left: RFEM Model | Right: Wind Load Distribution on Individual FE Elements

The cause of the problem can be visualized directly in RWIND Simulation. By default, calculations are based on a simplified model. Depending on the setting, the shell of the model can be refined or coarsened. An FE mesh is placed over the structure, so to speak, and depending on the level of detail, this FE mesh clings to the model. Figure 02 shows the extent of the level of detail that is too small. The surfaces standing on the façade are not displayed well enough and no wind flows between the cantilevered surfaces in the simulation, which is why these internal surfaces do not experience any wind pressure.

Figure 02 - Left: Wind Pressure on Structure | Right: Simplified Model

The level of detail can be adjusted in RWIND Simulation by 'Edit Model' or directly in RFEM in the settings for the wind load simulation (see Figure 03). Optionally, the simplified model can also be completely deactivated in RWIND Simulation.

Figure 03 - Setting Level of Detail in RWIND Simulation (Left) and in RFEM (Right)

In the case of a greater level of detail (corresponds to a finer FE mesh), the cantilevered surfaces are displayed cleanly and the FE elements are stressed accordingly (see Figure 04 and Figure 05).

Figure 04 - Model with Higher Level of Detail and its Results