This document explains how to set up and interchange the working units in MOSES.
Two sets of files are used to demonstrate the unit definition and units interchange to assess the longitudinal strength of a barge. The two sets of files can be found on ...\hdesk\runs\samples\how_to directory.
MOSES v10.14 was used in generating results for this work.
Specify Analysis Units
The analysis units are specified with the &DIMEN command and they are usually defined at the top of the file. The command syntax is
and the available options are
-dimen, -save, or -remember
The three options will be discussed with two examples below. Let us see the first set.
Long_str.cif and Long_str.dat
The -dimen option controls the current analysis dimensions and in long_str.cif we see
&dimen -dimen meter k-nts
When a -dimen option is used, any input that follows is to be consistent with meters and kilonewtons and all output will also be consistent. With this option available one can define input data in a system different than meters and kilonewtons. This feature is used in the second set of files.
In long_str.cif and long_str.dat all input is consistent in meters and kilonewtons and no further discussion is made. The results from this set of files will be used for comparison with the output from the second set.
Long_str_mtons.cif and Long_str_mtons.dat
In these files the same analysis is carried out but this time metric tonnes force are used instead. The syntax in the command and the data file is specific to demonstrate how analysis units are changed, data is specified, and then return to the initial units.
Let us look at Figure 1 where the implemented units in the command file can be seen better.
Remember that MOSES stores all the data in neutral format. It is the user’s responsibility to ensure that the units are consistent in each step. MOSES will not convert input data in any of the above steps. The benefit of the above scheme is that one can input a model using different units for various definitions. For example, a barge may be defined in metric units, while a jacket in English units.
Post processing results from the above two analyses shows that the banding moment and shear curves are identical even though in long_str_mtons the flexural rigidity EI was converted from kN-m2 to Te-m2 in
&describe body barge -section 113e11/9.81 0 75.333
Note that the above change from kN-m2 to Te-m2 is not automatic but the user has to responsibly carry out conversion. The above interchange can take place as many times as necessary as long as one respects the units chosen with the -dimen option.
Do not forget to issue the -remember option last (step E) to revert to the primary analysis settings (step A)
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