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Combination key

Details of Combination key

When defining an automatic or Eurocode type combination in SCIA Engineer, these combinations are regrouping the results of several linear subcombinations in one envelope result. Exploding these combinations to linear combinations will allow you to see the linear subcombinations that are calculated in the background:

However, it is totally unnecessary to explode any envelope combination: even if they are hidden, the linear subcombinations are always calculated and displayed if they yield the highest or lowest results. To know which of the linear subcombinations caused a certain value, you can look at the combination key.

Let us have a look at the preview of the internal forces below. We see that subcombination EN ULS/2 has yielded the highest bending moment. In the default post processing environment, the corresponding combination key is automatically displayed below the table: 1,35*LC1 + 1,35*LC2 + 1,5*LC5. Please note that this is not corresponding to the numbers of the exploded linear combinations. In the exploded combination this was combination EN ULS3, so please note that these numbers are not related and you should always look at the printed combination keys.

If the table with combination keys is not displayed, you can activate it in the properties window under output settings:

The option new combination from combination key allows you to create any type of combination (linear, nonlinear, stability) based on one of the combination keys in the results.  This allows to easily generate nonlinear combinations for all the dimensioning subcombinations, generate stability combinations for the keys that generate the highest compression forces, or find out which normal forces and shear forces correspond to the combination generating the highest bending moment.