Question:

How do I specify that the support skirt base ring is welded, not bolted, to the (skid) base plate?

Answer:

By default, COMPRESS assumes the skirt base ring is fully supported by a concrete foundation with full grouting.  An option is provided to indicate that the foundation is steel instead of concrete. This is option is available from the base ring dialog, as shown in the picture below.

When the steel foundation option is selected, the same analysis is performed for the base ring. The only difference is that the modulus of elasticity applied for the foundation will be that for carbon steel at ambient temperature rather than that for concrete. This will make a slight difference in the compressive load distribution acting on the base ring and may affect the base ring thickness and anchor bolt size.