# Is there any possibility in RFEM to consider friction for the horizontal reactions of a surface support?

For surface supports, this option is only available if there is also the nonlinearity defined in the local z direction (failure if contact stress in z is negative/positive). In the dialog box where you can edit the nonlinearity, you can find the "Friction in plane xy" option.

This option works as shown in the graphic dialog box: The support in the x and y direction is fully accepted only when reaching the contact stress Tau (contact stress Sigma multiplied by the friction coefficient). It is necessary to reduce this linearly in advance.

In order to use this option, a support must be in the horizontal directions. It can be defined as fixed or with an elastic spring. If the spring is defined with 0, no support is considered even though a friction coefficient has been entered.