Soil-in seismic calculation

Definition, application

Soil-in is an iterative cycle described in chapter "Soil-in calculation" .It is possible to combine it with calculation of seismic load cases (spectral analysis). In Scia engineer it is possible to use it in both post processing environments ppe v16 and ppe 'default', but there are some differences which are described below.

Definition, application

For spectral analysis with soil-in support on structure it is necessary to define surface support type soilin and define Load case with action type variable and load type dynamic with specification Seismicity. See "Seismic Analysis of Buildings".

In Solver setup it is necessary to define Soil combination, Maximum soil interaction iterations and Number of eigenmodes for spectral analysis. See "Required parameters for Soil-in calculation".

Where to find in ESA

How to run calculation

In both post processing environments this type of calculation is run as Linear analysis.

Calculation background for PPE 'default'

In ppev17 the schema of Linear analysis with seismic load cases and soil-in is:

Advantage of this solution is, that soil-in calculation is performed before modal analysis, so soil-in influences eigen frequencies of structure for spectral analysis.

Calculation background for PPE v16 and older

In ppev16 the schema of Linear analysis with seismic load cases and soil-in is:

Advantage of this solution is, that soil-in parameters for modal analysis are taken into account directly from solver setup, because soil-in calculation is on the end of calculation.

Disadvantage is, that parameters of soil-in have constant value for all surface supports.

Workround:

Same behavior of the calculation under ppe v16 as it is implemented in ppe 'default' can be achieved as follows: