How to choose the leadgin variable action in superposition with MAXIMA?

SOFiSTiK Teddy
#1

Hello,

I was wondering if it is possible to choose the “leading variable action” when I do superposition such has Frequent SLS with MAXIMA.

If yes, how can i do that ?

Best regards,

#2

If you have several actions with defined combination coefficients then maxima will check all possibilities - every action as leading one and the rest as following actions.

#3

Redefine the psi factor for every variable action in maxima (will only affect that maxima run)

Since you are in the frequent combination the leading action uses the psi_1 factor and the accompanying actions the psi_2 factor, so:

  • Redefine your forced leading action so that both psi_1 and psi_2 have the factor for psi_1
  • Redefine the remaining actions so that both psi_1 and psi_2 have the factor for psi_2

Now maxima can’t “look for” the worst leading action since you have enforced the combination factors.

#4

Hello,

the decision whether an action is the leading or accompanying one depends on several things:

  • Superposition value
    e.g. a QUAD force or bending moment of a beam or supporting force
  • Position in the structural member
    e.g. beam section in the middle of the span or at support
  • Safety factor gamma and combination coeffients psi

The program MAXIMA calculates for every superposition value at every position for an action the case leading and the case accompanying. The difference between both cases decides whether leading or not.

When you want to preset the leading action than it is possible in MAXIMA with an explicit defined combination. E.g. the action wind is the leading one:

COMB 1 EXTR EXPL TYPE DESI BASE 2100
ADD G FACU 1.35 FACF 1.0
ADD W FACU 1.5 FACF 0 ! leading action with safety factor gamu 1.5
ADD {QI} FACU PSIU FACF 0 ! all other variable actions as accompanying ones with gamu* psi0
SUPP ….

More information and descriptions can you find in our Online Tutorials: TEDDY or SSD → Online Help → Tutorials → Superpositions.

Regards
Sabine Fahrendholz
Senior Product Manager

#5

I have additional question.
Where and how can I see all combinations that MAXIMA calculates?
explicit linear combinations like 1,35xLC1+1,5xLC2+0,9xLC3…

#6

Use Trac feature

#7

Thank you very much, I think it is the best way to control combinations.

#8

I know TRAC and it show me only 1 decisive combination or?
If you know how to use TRAC to print out all processed combinations please let me know

#9

Hello,
as I wrote the superposition results are different in several points of the member.
The resulting load case combinations are not stored in the CDB, however it is possible to output them. In MAXIMA the printout is controlled via the ECHO options and the selection of the points in record SUPP.

e.g.
ECHO LOAD,FACT → for extended output
and
SUPP 1 EXTR MAMI ETYP BEAM TYPE N,VZ,MY FROM SLN 4
→ output of all beams of the SLN 4
SUPP 1 EXTR MAMI ETYP BEAM TYPE N,VZ,MY FROM 20030 TO 20036 INC 1 X 1[-]
→ output of beam no. 20030 till 20036 at beam ends

Regards
Sabine Fahrendholz
Senior Product Manager