All over the world, slabs and plates supported by piles and/or columns are built based on linear elastic calculations according to present codes. For infrastructural structures it is already recognised that taking into account nonlinear material behaviour such as arching or compressive membrane action (CMA) is contributing to the bearing capacity. Articles about this phenomenon always link it to a horizontal external constraint. For slabs in general, the slenderness is normally too large for profiting on this phenomenon. However, for industrial slabs with slenderness values of l/h=10-15, this is already adding some value. This phenomenon is found when performing a nonlinear analysis. DIANA is capable of setting up such an analysis for the user based on simplified input. Following the EC2 and the MC2010 the program makes the necessary nonlinear choices. In this paper it will be shown that around the point supports high compression membrane (cross sectional) action forces are occurring, even though the horizontal external constraints are missing. These compressive membrane forces give extra capacity to this zone. This is one of the reasons, why the shear stress failure for punching load of a slab is much higher compared, to the shear stress for a 2D beam. In the field area (mid-span), we see the counter effect with a residual tension membrane force.