Traffic loader in example file plate girder bridge

Hello everyone,

I am trying to learn the Traffic Loader module from Sofistik, by using Grasshopper. The example file that I am using can be found here:

https://www.sofistik.de/documentation/2020/en/rhino_interface/grasshopper/tutorials/plate-girder-bridge/plate-girder-bridge.html

Since this file contains an axis, I think it is a good file to practice Traffic Loader. However, I cannot manage to run the traffic loader without error messages. Could someone help me with the following questions?

  • I am using one of the axes on which the deck is modelled in GH. Is this the right way to do it? Can Sofistik ‘see’ that the deck is projected on this axis?

  • In my project where I would like to use Traffic Loader, my deck is modelled by using a Brep → Structural Area. Is it somehow possible to make the Traffic Loader work on this area? Perhaps by placing an axis in the middle?

  • In the Plate Girder example file, I constant get the error message shown underneath. I am probably doing something wrong, but I cannot find exactly what. All of the Traffic Loading tutorials I can find are either set up with SofiPlus or Teddy, and not Grasshopper like in my case.

    SOFiSTiK 2020-12.0.1863    ELLA   - EXT. LIVE LOAD ANALYSIS
     Output on file Plate Girder Bridge.plb
     Project data base Plate Girder Bridge.cdb -    70. access
     Workspace                   400.0 Megabyte
     +++++ error no.  2902 in program ELSF ; input line:   18
     Triangulized stiffness matrix not available
     Remarks: last loadcase must not be a support-displacement
              last loadcase must not be nonlinear
              CTRL SOLV 2 and 4 are not posssible to be used by ELLA
    

The converted user task of my Traffic Loader can be found underneath:

$ Automatically generated by Traffic Loader 2020-12.0 28-1-2022 09:09
$ Attention: Changes will be overwritten if the task is opened again!

+PROG SOFILOAD urs:31 $ Traffic Loader
HEAD POSITIONAL VARIANTS OF LOAD TRAINS
PAGE UNII 0

LANE A_1 TYPE RQ7.5 WL -2.7493 WR 2.7493 YLA -2.7493 YRA 2.7493

ECHO LANE FULL

$
LC NO 1200 TYPE D_1 TITL ‘EN 1991-2 Load model LM1’
TRAI LM1 P1 300 P2 299.81 P4 9.00005 P5 2.49983 P6 0 P7 3.4991 P8 899.875 P9 0 PFAC 1 PHI 0 PHIS 0 WIDT 2.99923 $$
XCON 0 V 0 FUGA 1
$
END

+PROG ELLA urs:31.1 $ Traffic Loader
HEAD AUTOMATIC EVALUATION OF LOAD TRAINS
PAGE UNII 0

SIZE URS 0 HDIV 3 $ 0.30

ECHO OPT LOAD VAL YES $ Loadtrains
ECHO OPT EVAL VAL NO $ Evaluation
ECHO OPT LPOS VAL FULL $ Load positions
ECHO OPT RES VAL NO $ Results

SHOW SNO A_1 TYPE BEAM NO 0 ETYP ALL
SHOW SNO A_1 TYPE QUAD NO 0 ETYP ALL

LSEL A_1 INT 7 DZ 0.01524 B 2.99923 $ RSEL GRP 0
CALC MXX LMAX 2 LMIN 1
CALC VY LMAX 4 LMIN 3
CALC VZ LMAX 6 LMIN 5
CALC MT LMAX 8 LMIN 7
CALC MY LMAX 10 LMIN 9
CALC MZ LMAX 12 LMIN 11
APPL FULL

SAVE LCB 200 TYPE G_2 TITL ‘ts’
CASE 1 GRP ALL
POSL A_1.0 TRAI 1200 FACT 1 YEX 0 P 2.49983 SYNC OFF PLON VAR PTRA VAR FUGA CODE IMPA ON EXCE FIX EXTR ALL OPT FREE

CASE 2 GRP GR31

CASE 3 GRP GR31

END

If someone could help me getting started on this, that would be greatly appreciated.

Thanks in advance!

You need to calculate a normal loadcase first, e.g. self weight.
That way ASE generates a stiffness matrix (the .$d1, .$d2 files) that can be used in an ELLA calculation.

Thank you. After trying to run ELLA, it keeps calculating for ages, without ending the calculation.
Is the traffic loader compatible with axes that are generated with Grasshopper? Is there an example where Traffic Loader is used with Grasshopper?

If your system is large and there are a lot of traffic lanes it will run for a very long time (calculation intensive).

Order results only for one element at first. So you can check whether it’s running as intended.