Question:

Why doesn't COMPRESS apply the maximum bending moment to the anchor bolts in my base ring report? Does this result in the required area of the bolt being reported as zero (0)?

Answer:

When full reports are selected (not minimal reports), COMPRESS reports the anchor bolt and base ring calculations for each load case described in the summary table at the top of the Base Ring report. When minimal reports are selected COMPRESS reports only the governing case.

The anchor bolts are subjected to the tension force arising from the overturning moment acting on the vessel from wind, seismic, etc. This tensile force is counter-acted by the weight of the vessel and contents. In some cases the weight may be greater than the uplift acting on the anchor bolt, in such a case there is no net uplift acting on the bolt (a message is so expressed in the base ring report) and there is no net tension force acting on the bolt. Thus the required bolt area is '0' (the bolt does not act in compression).

When all load cases result with no uplift acting on the bolt, the governing condition (reported when minimal reports is selected) results in the negative value of least magnitude (i.e.: it is the "least negative" value for the set of load cases). This will often correspond to the load case with the smallest value of weight W and may correspond to a load case with no bending moment.