Why is the sum of the loads different than the sum of support forces? What is the cause of it?

Question

Accepted Answer

In most cases, these differences can be attributed to a lack of convergence . Increasing the number of iterations and increments in the calculation parameters and FE mesh settings should help (see Figure 1).High jumps in stiffness result in numerical problems, which leads to errors in the results evaluation. In RSTAB, this is no major problem for a complete and analytical approach function. In RFEM, on the other hand, approximation approaches are used, which is more likely to prevent high stiffness changes. An example of this are rigid members (very high stiffness) which are connected to softer surfaces or members. In this case, the rigid member can be replaced by a beam member with a stiff cross -section or by stiffness members with high stiffness.In case of members with elastic foundations, it may happen that deviations may occur as well. If the members are not or only roughly divided, convergence problems occur. A practical solution is to select a 'finer' distribution of members in the FE mesh settings (see Figure 2).

Helpful Questions & Answers

Why is the sum of the loads different than the sum of support forces? What is the cause of it?

Answer

Keywords