A Case for Load Cases / Folders

cwharpe

Victor,

My friend has an intriguing project of late -- a full-size treehouse in his backyard (700 sf)! A consultant had prepared a structural report using an elaborate structural FEA software. As a curiosity, I was asked to compare results. Using beam elements, I am pleased to report Mecway agreed within 3% of the professional results. (I noted the expert used very few nodes.)

But the laborious process involved evaluating no less than (25) different Load Cases -- varying Vector combinations of DL (dead load), LL (live load), W & E (wind, earthquake/seismic, from 4 directions). For example:

• DL + 0.75LL + 0.525E(west)
  
• 0.6DL + W(south)
  
• DL + 0.7E(north)
  

Each vector (DL, LL, etc.) had between qty. 10-30 forces & uniform loads. Net result when all vectors were imported was 2-3 pages of non-descript loads that required finding and editing the forces of a particular Case, and suppressing the others.

I have two requests:

1. Include a means to herd the Loads into distinctly named Cases or Folders.
   
2. Attach a co-factor to each folder, such that aB=C, where a=amplification factor (1=default), B=folder values, and C=the final load values that are passed to the Solver. A value of a=0 would also provide a quick suppresion of that folder.
   

A huge Thank You for continuing to improve Mecway. It is proving to be an extremely useful tool.

~CWharPE

prop_design

is the existing configurations feature not helping!

cwharpe

The configurations feature is VERY helpful. But the setup requires sorting through individual forces (a list of qty. 140 for treehouse), turning the proper ones off or back on, editing the right forces to reflect the correct multiplier (e.g. 0.75*LL, 0.7*Esouth), then solving the new configuration. Rinse & repeat for the remaining (24) Load Combinations.

For models with long lists of forces, I'm convinced folders make things much tidier & folder Co-Factors give big savings on the editing time.

Thanks for the reply.

JohnM

When running many variations on the same model, consider running in batch:

1- set up and run model with all unit loads, set Mecway to output a scratch.liml
2- edit *.inp to capture the load files in a file called unit_loads.inp
3- add *AMPLITUDE cards to the loadings, with meaningful names
4- suppress original loadings, add CCX step input that *includes a my_amplitudes.inp and unit_loads.inp
5- create a script (many better ways to do this, example is just for concept) that outputs your desired scalings to a file called my_amplitude.inp, then runs Mecway, renames scratch.liml to a meaningful name

simple example attached - this is meant to get started, it can get much more sophisticated (input from csv files, monitor results, etc.) once you get the hang of it, just unzip and click run.bat

prop_design

hi cw,

i feel your pain on the multiple load entry and the laborious nature of turning them on and off. in a different thread i asked if we could get multi-select in the model tree. so you could use the control and shift keys like normal windows works. the idea being, you could easily select multiple loads and turn them off.

in email awhile ago i asked victor if he could implement spreadsheet like cells so you could copy and paste things from a spreadsheet into mecway. one instance is when trying to define laminates. another would be for Fx, Fy, Fz and Mx, My, Mz. There could be more. But I agree it would be nice if something could be done to make it easy to define multiple loads in the browser. with everything being text boxes, that makes it really a pain to copy and paste stuff over from a spreadsheet.

I'm not sure I understand the idea of using folders. I think the configurations is supposed to handle that aspect. If something could be done with the other aspects, I think configurations would work fine as is. But I may not be understanding what you mean.

the more people that ask for certain features. the more likely victor may implement it. in the meantime what john suggests is probably your only option.

cwharpe

prop_design

By Folders, I meant all the dead loads under a Tab called DL, all the live loads under a Tab called LL, etc. With amplification factor, say "a", attached to each Tab (default=1), then turning Tab OFF is a=0. Making a Load Combination of , say, DL + 0.75LL + 0.525Es is a snap to set up. Solve under new configuration window if you like.


JohnM

You are taking me to the next level. Haven't done scripting for awhile. I will look into your detailed example. Thanks.

cwharpe

@JohnM

I'm a total newbie with the CCX side. Couldn't get your example to work. CCX solver says "cannot open file MY_AMPLITUDES.INP".

Maybe I've got the file in the wrong place??

JohnM

Not sure of the issue, but for reference, I am running Mecway12 (but should work in all), and Windows 7. I downloaded the zip file, extracted, double-clicked run.bat and it seemed to run fine. Below are some details

The run.bat file
-creates the my_amplitudes.inp as it runs - see attached graphic
-runs Mecway - check the path
-renames the output files to a meaningful name.

The heart of this process is simply running Mecway in batch, with files that you *INCLUDE through CCX custom step contents. In this case, I have two files, unit_loads.inp and my_amplitudes.inp. Since I can modify these files externally without opening Mecway, this allows me to run a matrix of possible conditions in batch. There are many ways to vary these inputs, the example I use is a very simple one.

I would look at the files created after you double-click run.bat - do you get a my_amplitudes.inp file? Verify your Mecway path, and see that you don't have some strange file security restrictions where you are running.

I am pretty sure you can get this working, and once you do you will quickly see the utility.
Good luck!

sofien_73

Hi every one I am struggeling with the same kind of problems. I mean multiple loadcases studies with Steel frames according to EuroCode standards. I had made a lot of improvements to create liml xml file with the help of python librairie ( lxml for scripting liml xml file and openpyxl to link an input Excel file to the final liml file) but it is very difficult to deals with the and the several other . Victor if possible could we have a more accurate/better method to handle multiple loader cases on the next version of Mecway? And an other issue that I have noticed is that we didnt have all the constraints for beam application ( only rigid or pinned type ) could you had a user type which can allow us to fully constrains nodes (in local and global direction). Thanks

sofien_73

SORRY...
Second try some words were missing.
Hi every one I am struggeling with the same kind of problems. I mean multiple loadcases studies with Steel frames according to EuroCode standards. I had made a lot of improvements to create liml xml file with the help of python librairie ( lxml for scripting liml xml file and openpyxl to link an input Excel file to the final liml file) but it is very difficult to deals with the < configurationactive >and the several other < configurationsuppressed >. Victor if possible could we have a more accurate/better method to handle multiple loader cases on the next version of Mecway? And an other issue that I have noticed is that we didnt have all the constraints for beam application ( only rigid or pinned type ) could you had a user type which can allow us to fully constrains nodes (in local and global direction). Thanks

Victor

Since those posts, Mecway now has folders (called groups) for loads, but still not cofactors yet. Thanks for reiterating the need for them.

The Displacement and Node rotation constraints allow you to choose the DOFs to constrain in either global or arbitrary directions. With the internal solver, you can also use Flexible joint on beam to release DOFs in beam coordinates.

sofien_73

Thank you Victor.

Sebastianmaklary

Great to have a .bat file posted. By reading how other people use them to automate tasks it seems to be something I need but I just never knew what a .bat file should be like.