2160x
003442
2021-07-27

Question

I would like to define a line support with ineffective tension and apply the tension force on this line using a nodal support instead. Why does the line support still receive a tension force?


Answer:
If nodal supports are modeled on supported lines, this may lead to problems and incorrect definitions. Therefore, the following warning message appears in the plausibility check.


Internally, the line supports and nodal supports are treated on each FE node. If a nodal support is located on a line support, an FE node thus receives several support definitions. If the defined directions of the supports are not equal, this is not critical and the warning message can be ignored. If the same directions are defined several times, discrepancies may occur.
If the line support and the nodal support on this line fail under tension, a tensile force thus arises in the FE node, which, however, is part of the line and nodal support.


To avoid this behavior, it is possible to insert a short line without a support definition in the area of each nodal support. It may also be useful to model a tension bracket using a newly defined member. The force transmission can then be adjusted using the support of the member, the member type itself, and the member end release.


In general, the support stiffnesses should be estimated in a realistic way; in the example, rigid supports were assumed as a simplification.


Author

Mr. Metzkes is responsible for development in the area of steel structures and provides technical support to our customers.

Downloads