Modeling of a Prestressed Concrete Sleeper

- February 26, 2019 at 9:07 am
  
  parco
  Subscriber
  
  Hello Community...
  
  Am trying to model a prestressed concrete sleeper in ansys workbench and planning to use solid65 for concrete and link180 for rebar. Since am new to ansys I've started with a simple prestressed beam and through following tutorials been able to model an RC beam but stranded on how to apply prestressing to the rebar in workbench. Am requesting for your assistance on the above and any tutorials shared will be highly appreaciated.
  
  Thanks...
  
  Francis Wantono
- February 26, 2019 at 9:16 am
  
  jj77
  Subscriber
  
  I would try and use the Loads/Bolt Pretension on the lines bodies that will be truss/link elements.
- February 26, 2019 at 9:56 am
  
  parco
  Subscriber
  
  Meaning I apply a prestressing force on the line elements as a component force and then the vertical force on the model in the same step.
- February 26, 2019 at 10:13 am
  
  jj77
  Subscriber
  
  Well I would apply the bolt/pretension first on the rebar/line bodies, and then apply any other loads.
  
  Applying an initial strain via commands (inistate command) might also be a better way.
  
  See this post:
  
  /forum/forums/topic/confirming-prestress-initial-strain-in-link180/
  
  Also the link8 element has a prestrain that can be assigned (never used any of these though, and also link8 are not supported so I would not look into that - use link180 with instate for pre strain).
- February 26, 2019 at 12:13 pm
  
  parco
  Subscriber
  
  I,ve gone through the discussion in the link above. I have a prestressing force of 24kN, how can I relate this to the inistate command and maybe would be glad if you shed more light on the command. I would like to try out both methods that you've proposed.
- February 26, 2019 at 12:50 pm
  
  jj77
  Subscriber
  
  Never used it, but in the help manual there is plenty of info.
  
  Open help and copy and paste this link into the ansys help browser:
  
  https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v192/ans_adv/Hlp_G_INSTAPPL.html%23initstressappl
- February 26, 2019 at 3:49 pm
  
  peteroznewman
  Subscriber
  
  Divide the pretension force by the cross-sectional area to get the prestress. Divide that by E to get prestrain.
- February 26, 2019 at 4:49 pm
  
  parco
  Subscriber
  
  Ok...
  
  Thanks for the responses...
  
  Let me try out, and get back to you
- February 28, 2019 at 7:57 pm
  
  parco
  Subscriber
  
  If am to use the inistate command, am I supposed to insert the command on each line body just like the link180 command
- February 28, 2019 at 8:15 pm
  
  parco
  Subscriber
  
  Have tried to use bolt prestension to apply the prestressing force on the line bodies, but not sure it's working. Failing to select the bodies to be able to apply the pretension in the right direction. Below are the line bodies that I've created with link180 commands.
- February 28, 2019 at 8:24 pm
  
  jj77
  Subscriber
  
  The correct way to do it is to use inistate.
  
  not sure, but I would add it on every line body which is link180 converted.
  
  Remember to use the local element system when defining the pre strain or stress, below is an example for your reference only
  
  et,matid,link180
  
  sectype,matid,link
  
  secdata,1 ! cross sec. area (change)
  
  mp,ex,matid,200E9 ! Young's mod. (chnage)
  
  mp.dens,matid,7800 ! dens
  
  INISTATE,SET,CSYS,-2 ! LOCAL ELEMENT SYSTEM FOR PRE-STRAINS
  
  inistate,set,mat,matid ! selects only links with this matid
  
  INISTATE,SET,DTYP,EPEL ! PRE STRAIN
  
  INISTATE,DEFINE,,,,,1E-7 ! STRAIN VALUE (change)
- March 1, 2019 at 2:48 pm
  
  parco
  Subscriber
  
  Thanks jj77 for the help...
  
  I'll try this and get back to you
- March 4, 2019 at 9:31 am
  
  parco
  Subscriber
  
  Good day members...
  
  I'm attaching my trial ansys16 workbench file of a sample of RC & Prestressed beam using the inistate sample command provided by jj77.
  
  Please look through and help guide me where I need to improve for my project.
- March 4, 2019 at 9:35 am
  
  parco
  Subscriber
  
  Also Help with more explanation about the coordinate system in the inistate command.
- March 4, 2019 at 9:38 am
  
  parco
  Subscriber
  
  For the stress strain data for the solid65 command shown below, does it have to be 35 inputs or I can use any number of inputs.
  
  TB,MISO,MATID,1,35,0
  
  TBTEMP,22
  
  TBPT,,0.0001,2.925
  
  TBPT,,0.0002,5.7
  
  TBPT,,0.0003,8.325
  
  TBPT,,0.0004,10.8
  
  TBPT,,0.0005,13.125
  
  TBPT,,0.0006,15.3
  
  TBPT,,0.0007,17.325
  
  TBPT,,0.0008,19.2
  
  TBPT,,0.0009,20.925
  
  TBPT,,0.001,22.5
  
  TBPT,,0.0011,23.925
  
  TBPT,,0.0012,25.2
  
  TBPT,,0.0013,26.325
  
  TBPT,,0.0014,27.3
  
  TBPT,,0.0015,28.125
  
  TBPT,,0.0016,28.8
  
  TBPT,,0.0017,29.325
  
  TBPT,,0.0018,29.7
  
  TBPT,,0.0019,29.925
  
  TBPT,,0.002,30
  
  TBPT,,0.0021,30
  
  TBPT,,0.0022,30
  
  TBPT,,0.0023,30
  
  TBPT,,0.0024,30
  
  TBPT,,0.0025,30
  
  TBPT,,0.0026,30
  
  TBPT,,0.0027,30
  
  TBPT,,0.0028,30
  
  TBPT,,0.0029,30
  
  TBPT,,0.003,30
  
  TBPT,,0.0031,30
  
  TBPT,,0.0032,30
  
  TBPT,,0.0033,30
  
  TBPT,,0.0034,30
  
  TBPT,,0.0035,30
- March 4, 2019 at 10:04 am
  
  jj77
  Subscriber
  
  The coordinate system is just the local coordinate system of the element (it is easier to apply there since that is used when applying prestress).
  
  For more info of local coordinate systems for element search the ansys help manual.
- March 14, 2019 at 6:51 am
  
  parco
  Subscriber
  
  Hello...
  
  Can you help shed more light on the TBDATA for solid65 command.
  
  Absence of the data table removes the cracking and crushing capability. A value of -1 for constant 3 or 4 also removes the cracking or crushing capability, respectively. If constants 1-4 are input and constants 5-8 are omitted, the latter constants default as discussed in the Mechanical APDL Theory Reference. If any one of Constants 5-8 are input, there are no defaults and all 8 constants must be inpu
  
  Based on the above explanation, what would this mean? I got the command below from a tutorial and I am trying to understand it but am lost some how on the inputs in the command.
  
  TB,CONCR,MATID,1,9
  
  TBTEMP,22
  
  TBDATA,1,1,0.8,1.5,25
- March 14, 2019 at 6:57 am
  
  parco
  Subscriber
  
  Does it mean I input only the first 4 constants and the latter constants default as discussed in the Mechanical APDL Theory Reference.
  
  TB,CONCR,MATID,1,9
  
  TBTEMP,22
  
  TBDATA,1,2,3,4
- March 14, 2019 at 8:56 am
  
  parco
  Subscriber
  
  When I run the solution with this solid65 command, the stress strain points for 60 MPa concrete I get an error
  
  TB,MISO,MATID,1,35,0
  
  TBTEMP,22
  
  TBPT,,0.0001,3.772
  
  TBPT,,0.0002,7.544
  
  TBPT,,0.0003,11.316
  
  TBPT,,0.0004,15.085
  
  TBPT,,0.0005,18.851
  
  TBPT,,0.0006,22.606
  
  TBPT,,0.0007,26.343
  
  TBPT,,0.0008,30.049
  
  TBPT,,0.0009,33.705
  
  TBPT,,0.001,37.289
  
  TBPT,,0.0011,40.769
  
  TBPT,,0.0012,44.109
  
  TBPT,,0.0013,47.264
  
  TBPT,,0.0014,50.185
  
  TBPT,,0.0015,52.819
  
  TBPT,,0.0016,55.111
  
  TBPT,,0.0017,57.010
  
  TBPT,,0.0018,58.469
  
  TBPT,,0.0019,59.454
  
  TBPT,,0.002,59.943
  
  TBPT,,0.0021,59.932
  
  TBPT,,0.0022,59.433
  
  TBPT,,0.0023,58.476
  
  TBPT,,0.0024,57.108
  
  TBPT,,0.0025,55.383
  
  TBPT,,0.0026,53.367
  
  TBPT,,0.0027,51.125
  
  TBPT,,0.0028,48.724
  
  TBPT,,0.0029,46.224
  
  TBPT,,0.003,43.680
  
  TBPT,,0.0031,41.138
  
  TBPT,,0.0032,38.637
  
  TBPT,,0.0033,36.205
  
  TBPT,,0.0034,33.865
  
  TBPT,,0.0035,31.632
  
  yet with the same command when I use the stress strain points for 30MPa concrete the solution runs