Automated Tools Questions


Q: I have performed a transportation analysis of a jacket using the installation macros, where are the restraint loads at the ends of the tie-downs?
REV 7.01

A: You cannot find them because the ends of the tiedowns are not restrained, they are connected to the barge. Look instead at the beam loads in the tiedowns.


Q: What are the load cases MEANXXX that are generated when doing a transportation analysis?
REV 7.01

A: These are the mean load cases due to wind in the directions specified.


Q: When doing a transportation analysis using the installation macros, I get two reports one which says results for maximum axial load greater than 0 another for maximum moment greater than zero. Why?
REV 7.00

A: Theses are reporting the loads at a point in the element. The first reports the loads at the point where the axial load is a maximum, the second the point where the moment is a maximum. Thus forces reported can be different for the same load case because the points will be different.


Q: Why are my tiedowns not shown in the pictures?
REV 7.00

A: The default picture shows panels, and elements which have some load attributes. Your tiedowns have neither weight nor buoyancy and hence are not shown. Give them either a weight or a buoyancy and they will be in the picture.


Q: How can I change the water depth for tow motions when I use the transportation macros?
REV 6.01

A: For transportation, this depth is set to 5000 feet or meters, so that you always get results for deep water waves. The automated installation macros were designed to remove some of the complexity of running MOSES, and this is accomplished by limiting choices. If we did not allow for a particular parameter to be changed, in all likelihood it is not meant to be changed.


Q: I am using the Automated Installation Macros to perform a transportation with time synthesis. I noticed that there are tension reactions even though the solution was supposed to be nonlinear.
REV 6.01

A: The nonlinear solution applied only to the waves. To account for wind, the difference between the static wind cases and the frequency domain mean is added. This produces the tension.


Q: I did some tests for using the macro KG_ALLOW, and I found that the reported maximum allowable KG (for the same draft) had different values when the user applied different weights. For intact condition, is it true that there should be only one maximum allowable KG value for one single draft?
REV 6.01

A: The kg_allow macro computes an allowable kg for any weight the user has not defined. In other words, the allowable kg will change when you define weights. Traditionally, this is used with no user defined weights and then the allowable kg is the kg of the total weight. This topic is also addressed in the workbook Gentle Introduction to MOSES.


Q: What is the definition of all of the load cases defined for an automated transportation analysis?
REV 5.09

A: Here is the basic definition of the load cases:

 
L = The "LOADOUT" case - no tiedowns at tow position.
 
F = The "FRQMEAN" case - Tiedowns included in still water.
 
M = Similar to F, but with wind included.
 
Z = The probable maximum stress deviation from the mean.
These are always positive.
 
X = The probable maximum stress deviation added to the mean
with the sign of the mean, L.
 
T = Either -1 or -2 times Z depending on whether or not you
said the tiedowns could take tension.
 
S = X + M - F.
 
C = L + M - F - Z.
Essentially, the L, F, M, Z, and X cases are "not of interest" and are only used to get the T, S, and C cases. The T cases are for checking tiedowns. These are simple in that they have zero mean, so we simply take the negative of the dynamic deviation and check it.

The S cases cover nearly all of the beams. This is the mean plus the dynamic deviation with the sign of the mean plus the wind. (Notice that M - F is the effect of wind alone). There are some instances, however, where a beam is slightly in tension in the mean and will be in compression due to the dynamic deviation. The C cases are designed to capture this situation. It is the mean plus the wind minus the dynamic deviation.


Q: I am doing a transportation analysis using the Automated Installation Macros and already have tiedowns in my structural model. What is the easiest way to fix this situation?
REV 5.08

A: First, remove the beams that model the tiedowns from your model. For the macros to work properly, the connections must have a specific part name and class type. Now, since you already have nodes for the barge end of the tiedowns, you can use them as follows:

~tied   TUBE 36 1.25 -fyield 50 -dens 552.72
&set t_rel = -relb ry rz -rela ry rz
&set nb = *d502020 *d502040 *d502060 *d502080 \
*d508020 *d508040 *d508060 *d508080 \
*d502040 *d508040
&set ne = *D241020 *D241040 *D241060 *D241080  \
*D249020 *D249040 *D249060 *D249080  \
*D242050 *D248050
&loop i 1 8
&set n1  = &token(%i %nb )
&set n2  = &token(%i %ne )
&set vec = &point(%n1 -b) &point(%n2 -b)
&set vec = &number(addv -1 %vec )
pconnect   %vec  ~tied %t_rel  &token(%i %nb) *b@
&endloop
The key here is to build a matching pair of node lists, nb for the nodes on the barge end and ne for the structure end. The loop computes a vector along the centerline of the tiedown to define the barge end and defined the tiedown. Be careful that the nth node in one list corresponds to the same tiedown as the nth node in the other.


Q: Why do I get the following when using the Automated Transportation Macros?

        *** WARNING: No Objects Selected by Selector 0
        ==============================================
     *** ERROR: Could not Find Close Point In Part PJACKET
     =====================================================

REV 5.05

A: You are probably using an old barge with the new macros, and now you need to define the variable V_NPREF in the barge data file. Please follow the instruction in the document Vessel Library under the section Adding Models. (For details, click here.)