Different Units for materials

[kesavapraba]

Dear Friend, First of all OpenSees does not have any option like SAP2000 or ETABS where you can easily change your units system. OpenSees allows the user to adopt the basic units system (N-mm-sec, kN-m-sec etc). Adopt anyone system as you wish, but be consistent with what units system throughout your model. I would suggest you to create a separate tcl file for units conversation if you want. For example , if suppose your basic unit system is in N, mm, sec and now you have force F of 100 kN. Then, you will have to do 'set F [expr 100*$kN]. But before doing it, you should have defined what that kN is in your units tcl file. That is your units file should have the line 'set kN [expr 1000.0]. There is already LibUnits.tcl file available in OS wiki page. Please refer that. All the best

[kesavapraba]

Dear Friend, Why don't you try creating two different system of units tcl files and source the file at just before appropriate places? For example, you have units system in N.mm.sec at start of your code, then if you want to define BondSlip material, you source psi based units tcl file. Once that definition is over, immediately below that material command again source N.mm.sec based units tcl file. Just try it. Thanks

[kesavapraba]

Dear Friend, Have tried as per the protocol I mentioned ? See, say there are two units tcl files, then you are calling one file at start of your code. Now comes the definition of your BondSlip material which requires the units in psi..So just above the line where you define the material, you call the 2nd units tcl file which has the psi as base unit. This is where the whole conversation takes place. Now you can give material parameters in MPa for BondSlip material. Once done wthe definition, immediately in the below line, you again call the default units tcl file.