# How the rinf and rsup coefficients are taken into account for SLS checks

$$SLS checks in IDEA StatiCa automatically take into account the influence of the rinf and rsup coefficients for prestressing effects. Therefore, it is not necessary to consider these effects in combination factors. BeamThe combination factor defined by the user for prestressing load case is considered just for internal forces presented in Beam. For code-check purposes, the effects of prestressing are defined by the area of the tendon and its initial stress. The combination factor for code checks is always equal to one.BIM - importIn combinations of the global model, the coefficients of load cases containing prestress should be equal to 1.0. The coefficients rsup and rinf will be applied as described above.$$