# Reaction force for screws

Project description:

I am trying to find the reaction forces of a vertical turbine tower foundation, in order to dimension the screws which are used to fix it to the ground. I made some hand calculations first and then I wanted to validate them making a simple model of the base and check the reaction forces where the screws are mounted.

First of all, I am new to Simscale so I am not sure if the settings of the simulations are correct so I would appreciate if someone could give some feedback on the simulation.

Basically there are some remote loads at above the base which have as assigned faces the areas where the turbine tower and the base meet (blue). The tower weight is applied over the blue areas too. Then on top of the base the generator is installed so the weight is applied as a mass over the area around the center (red).

The areas in green are the sections where the screws will go so they are modelled as fixed supports. The base is a thin plate so I only fixed the bottom face of the plate, I am not sure if I should fix all the faces around that area.

What I want is the reaction force in the vertical direction to know how much force the screws have to hold. On the “Result control” tab I created a solution field showing the reaction force and then some “data Points” also showing the reaction in the vertical direction (Z).

The results I am getting on the solution field make sense in terms of where the positive and negative forces appear, but I am quite unsure if I should take those values or if they are a result of a stress concentration from the simulation, as they are much higher than expected.

This is the solution field for the reaction force in Z, which gives maximum values around 50 to 60 kN:

I also set a Volume Calculation for the reaction force in the Result control tab, which gives me the Max and Min, values and correspond to the ones in the Solution field.

My issue here is that if it would be unwise to follow the value of 53kN I got from the simulation to dimension the screws or if it should be modelled in another way and this high value is due to stress concentrations in the model.

Any feedback on this issue is welcome.

Hi!

What you want here is a Result Control Item - Area Calculation - Sum of Reaction Forces, assigned to the faces with fixed supports.

This will yield the total reaction force in the selected direction.

Hi!

Thank you for the feedback, I will try using the Area Calculation on the supports and see what values I get.

Thanks a lot!