Post-Processing Beams Post-Processing Beams

Structural Post-Processing results for beams are obtained with the command:


     BEAM_POST, TYPE(1), ...., TYPE(i)  -OPTIONS

where TYPE(i) must be chosen from LOADS, CODE_CHECK, H_COLLAPSE, ENVELOPE, STRESS, COUNT, NT_FATIGUE, or FATIGUE, and the available options are:


     -CLASS, :CLS_SEL

     -NODE, :NODE_SEL(1), :NODE_SEL(2), :NODE_SEL(3), :NODE_SEL(4)

     -ELEMENT, :ELE_SEL

     -LOAD, :LSEL

     -DURATION, :DURATION_SEL

     -CODE, TYPE, CCAT

     -STANDARD, L(1), T(1), ..... L(n), T(n)

     -SUMMARY, L(1), T(1), ..... L(n), T(n)

     -DETAIL

     -DOF_SEL, DOF

     -REPORT, YES/NO

     -FILE, YES/NO

     -B_LOAD, YES/NO

     -EQUIVALENT, YES/NO

     -RESIZE, CONT

     -COSTS, STCOST, RCOST

     -UP_CLASS, YES/NO

     -S_BINS, S(1), S(2), ......, S(n)

     -SLA_COEFFICIENT, S_COE

     -SLA_DAF, S_DAF

     -SLA_CDAMP, S_CDAMP

     -SLA_FIXITY, S_FIXITY

     -SLA_MULTIPLIER, S_VEL(1), S_MUL(1), ... S_VEL(n), S_MUL(n)

Here, one will only receive results for elements which match the selectors defined with the -CLASS, -NODE, and -ELEMENT options as described previously and for cases which match :LSEL which is defined with the -LOAD option. For COUNT, NT_FATIGUE or FATIGUE, all durations which match :DURATION_SEL defined via the -DURATION option will be considered. If no values are given for TYPE(i), then results for all TYPEs will be produced.

Here, a TYPE of

With the exception of a TYPE of COUNT, the extent of the reports which will be produced is controlled by which of the three report types were selected and the report limits. With a -STANDARD or -SUMMARY report, L(i) and T(i) are used to specify a range of values for which a given report will be printed. Remember, the beams for which results are computed is already restricted by the -CLASS, -NODE, and -ELEMENT selectors, and the load cases by the -LOAD selectors. Thus, here we are talking about restricting what is reported out of what is computed. The easiest of these to describe is -DETAIL. Here, all the results are printed. With -STANDARD, only the result with the greatest "value" is a candidate for reporting, and it will only be reported if the value is between the report limits specified for that report. What is meant by "value" depends on type and will be described later. With a report option of -SUMMARY, only the result with the greatest value for a class is a candidate for reporting. One can specify as many ranges as he desires, or he can omit all data following the option. If no ranges are specified, one report for all ranges of value will be printed. An option of -STANDARD will result in a report of the results for the maximum "value" over all selected load cases for each member selected. If one specifies an option of -SUMMARY, this report will be reduced to the results for only the selected element in each class which has the greatest "value". Notice that -DETAIL, -STANDARD, and -SUMMARY may all be used on the same command to produce reports of all three types. Also, if no options are specified, then a default of -STANDARD is assumed. For a type of STRESS, the reporting criteria is the Von Mises stress divided by the yield stress, for a type of FATIGUE, the value is the CDR, and for all others except LOADS it is the code unity value.

For a TYPE of LOADS, the value used for determining the range is the absolute value of DOF in bforce or bforce-blength units. For this type, The -DOF_SEL option is used to specify the degree of freedom to be used as the reporting criteria. With this option, DOF is selected from the list: FX, FY, FZ, MX, MY, MZ, SHEAR or MOMENT. Only one value may be selected, and the default value is FX, axial. The value for DOF determines which quantity of the beam is used as the criteria for selecting the load case to report. When using the -STANDARD or -SUMMARY options, only the load case providing the highest absolute value of DOF is reported. The options -REPORT and -FILE operate only with a TYPE of LOADS. These options are used to control whether or not the results are written to a post-processing file, or the standard output file. The default is to write them only to the output file. If -FILE YES is specified, then the results will be written to both places. If -FILE YES -REPORT NO is specified, then the results will be written to the post-processing file only.

The options -CODE, -EQUIVALENT, -RESIZE, -COSTS, -UP_CLASS, and -B_LOAD are applicable only to a TYPE of CODE_CHECK. The type of code which will be used depends upon the last -CODE option. Here, TYPE may be either AISC, API, NORSOK, or ISO. The value CCAT defines the class of check for AISC or API type checks. It should be omitted for ISO or NORSOK type checks and it must be either WS or LRFD for AISC or API checks. If it is omitted for these checks, WS will be assumed. If one wishes to use an LRFD check, it is his responsibility to build load cases which include the proper multipliers. This option is remembered between BEAM code checks and JOINT checks. Thus, if one has previously used the -CODE option he need not be re-issued. If one is checking NORSOK or ISO codes, non tube beams will be checked using EUROCODE 3. No National Annex changes are considered and class 4 sections are treated as failures.

None of the codes are clear in how to treat non-prismatic members with respect to buckling. If one uses the -EQUIVALENT option with NO, then each section is checked using a slenderness based on the geometrical properties of that section, the "k" factor, and the length. If, however, this option is used with YES, then the slenderness of each section will be based on an estimate of the true buckling load of the element; i.e. a Raleigh Quotient will be used to compute the Euler critical load in the element and then a slenderness (and hence a radius of gyration) will be computed for each section which when combined with the standard formulae yield the estimated Euler buckling load.

The -RESIZE option directs MOSES to resize the selected classes so that each member will have a unity ratio less than one for the load cases considered. If CONT is UP and a class has a unity ratio less than one, no change in the class will be made. If either the unity ratio is greater than one or CONT is UPDOWN, the class will be resized. The manner in which MOSES picks a new member depends upon the table selector specified on the -RDES option for the class definition command. The shapes selected by the selector are assigned a cost based on the two unit costs defined via the -COSTS option. Here, STCOST is the cost of steel in monetary units per bforce, and RCOST is the corresponding cost of adding a single hydrostatic ring. The selected shapes are then tried in order of increasing cost until a workable shape is found. If -UP_CLASS is specified with YES/NO equal YES, then the new sizes will be stored in the database. Otherwise, the original sizes will remain. If -B_LOAD is specified with YES/NO equal to YES, a third line will be added to the code check output. This line contains the loads which produced the reported stresses.

For a TYPE of ENVELOPE, the maximum and minimum internal element loads are summarized for all selected load cases. This is quite useful in understanding the nature of loadings in the beam elements of a structure. If -DETAIL is specified as an option, the envelope of loads is reported at all load points. With an option of -STANDARD, the maximum and minimum values are reported once, for any location on the beam.

The -S_BINS option is applicable only to a type of COUNT. It is used to define a set of "bins" by stress range to accumulate the cycle data. Here, S(1) (ksi or mpa) marks the "top" of the first bin, S(2) the top of the second bin, etc. The stresses which are accumulated include the stress concentration factor.

The options -SLA_COEFFICIENT, -SLA_DAF, -SLA_CDAMP, -SLA_FIXITY, or -SLA_MULTIPLIER are applicable only to a TYPE of FATIGUE. They define the parameters used in frequency domain slamming fatigue are are discussed in the section on Beam Fatigue Due to Slamming. If you do not want to consider slamming, you should use

     -SLA_COEFFICIENT 0.

Also with FATIGUE, the meaning of -DETAIL, -STANDARD, and -SUMMARY is a bit different. -DETAIL is ignored. For -STANDARD, one receives the total CDRs for all computed points where the maximum of the CDRs lie between L(i) and T(i). Finally, for -SUMMARY, one only receives a report of the maximum CDR for all of the computed points which lie in the specified range.