Question:

Does COMPRESS include an initial bolt preload when designing anchor bolts and base plate? What is the preload used?

Answer:

COMPRESS provides the option for the designer to specify a preload on the anchor bolts. The preload, if applied, may affect the design of the anchor bolts, base ring, anchor bolt chairs and skirt. The benefit of a preload is that it reduces sway in the vessel due to wind as well as reduces the stress variation in the bolts due to cyclic loading .
 
If no preload is specified by the designer, then none is applied by COMPRESS.
 
Further information and recommendations regarding anchor bolt preload can be found in the publication "Wind Loads and Anchor Bolt Design for Petrochemical Facilities" by ASCE (American Society of Civil Engineers) ISBN 0-7844-0262-0.