In the RF‑STAGES module, I get a message about instability. RFEM calculates the model without any problems. How can I solve this?

Answer

Basically, you should pay attention to the following points:

Entering Model

The structure in RF‑STAGES and RFEM may differ due to the definition in RF‑STAGES. Therefore, the structure in RF-STAGES may be different than in RFEM. In order to find the instability at a certain construction stage, it is necessary to model the structure in this construction stage in RFEM and take it into account separately. In this context, it should also be noted that the entries are not synchronized between RFEM and RF-STAGES. For example, a member end release removed in RFEM is not automatically removed in the RF-STAGES model.

Method of Analysis

RF-STAGES calculates permanent load cases according to the large deformation analysis. As a result of this analysis, instabilities may occur which are not present in a load case when calculating according to the linear static analysis (critical load problems), for example.

Special Structural Elements

Some of the structural elements available in RFEM are not supported in RF‑STAGES. These structural elements can also cause the instability in certain cases. The following structural elements are not fully supported in RF‑STAGES:

  • Line hinges
  • Member elastic foundations
  • Sets of members
  • Intersections
  • Nodal releases
  • Line releases
  • Surface releases
  • Nodal constraints

Keywords

RF-STAGES instability construction stage calculation error stiffness matrix singular error 10060 error 10134

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RFEM Other
RF-STAGES 5.xx

Add-on Module

Consideration of construction stages during a building phase

Price of First License
850.00 USD
RSTAB Other
STAGES 8.xx

Add-on Module

Consideration of construction stages during a building phase

Price of First License
850.00 USD