8.2 Strusoft example

8.2 Strusoft Example

This example was created for demonstration purposes by Strusoft for the Peikko / Strusoft presentation seminar on 2021-05-25. Strusoft kindly sent us the original file, which we have used to run some tests.

The modified files and our hand calculations can be downloaded below.

Three modifications which have been done in these calculations.

  • Continuous plate / panel

  • Transversal flexural stiffness factor 1.0 / 0.1 / 0.01

  • Boundary condition / spring settings 1E+07 / 1E+06 / 1E+05


The results are shown for maximum moment and deformation in the beam.

The image below shows an example screenshot from FEM-Design, showing the moments in the beam with continuous and panel hollow core system, with transversal flexural stiffness factor 1,0, and boundary condition spring settings ranging from 1E+07 to 1E+05.

The theoretical correct result for the beam is 332 kNm (for a beam span of 9,45m).


This summary diagram shows My values for all calculations.

  • Boundary condition spring settings 1E+07 / 1E+06 / 1E+05.

  • Transversal flexural stiffness factor 1,0 / 0,1 / 0,01.

With boundary condition setting 1E+07 and transversal flexural stiffness factor 1,0 the moment in the beam is just 56% (185 / 332) of the actual moment, and thus critically underdimensioned.

Reduction of the transversal flexural stiffness factor to 0,1 reduces the mismatch to 86% (286 / 332), while a further reduction to 0,01 gets the result correct by 96%.

On the other side, changing the boundary condition to 1E+06 increases the values just to 59%. A further boundary condition change to 1E+05 will get the result up to 61%

A change to panel in the calculation while keeping boundary conditions at 1E+07 will give results that match the theoretical values by 85%.

Changing both values or doing a panel calculation with 1E+05 boundary conditions will give results close to the theoretical values (ca. 99%).

The most critical factor by far in this example therefore is the transversal flexural stiffness factor.


Displacement values range from 27mm to 49mm in this example, the lowest values corresponding with the lowest My values.


There is little to no effect of the transversal flexural stiffness factor to the 1. and 2. eigenfrequencies. The effect of calculation as panel is also quite limited in this test example.



2021-05-28 First time release

2021-06-10 Eigenfrequencies