How to make envelops from multiple load cases？

In the USA AASHTO code, Canidian CSA code and other code, such as Chinese Highway code,
if there are multiple lanes on the carriage way, designer need to consider traffic load on the combination of different lanes
E.g. if therer are three lanes, L1, L2 and L3
Traffic load on L1, LC1
Traffic load on L2, LC2
Traffic load on L3, LC3
Traffic load on L1 and L2, LC4
Traffic load on L1 and L3, LC5
Traffic load on L2 and L3, LC6
Traffic load on L1, L2 and L3, LC7
Total seven load cases (LC1~LC7) then need to be combined to be 2 envelops
ENV1 for max load effect, and ENV2 for min load effect.

How to achieve it in Sofistik?

I am also very interested in this question, hope you get a good answer!

I am also very interested in this question

Hi,

you have to do intermediate combination in maxima for any combination you descibed
L1, L2, L3, L1+L2, L1+L3, L2+L3 and L1+2+3.
Then in next maxima you superpose enevelopes of first maxima (all loadcases are excluding).
Final result is envelope of all combinations.

Hello,

one possibility is to make pre-superpositions and finally an envelope about these results.
Another possibility is to use load groups. A small example for demonstration of both way is describe in our Online Tutorial which is available in SSD or TEDDY via Help → Online Help → Tutorials → Superpositions → Superposition of Load Groups. Using load groups the pre- and end-superpositions are done automatically in MAXIMA. . Subsequently, the results can be checked for a superposition value at a specific point of the structure with the tracer → MAXIMA record TRAC.

In the Online Tutorial General Explanations for the Use of MAXIMA – Action Combinations in order to get Design Forces or Load Case Combinations some design codes are explained e.g. the action combinations according to ACI 318-14 which is similar to AASHTO.

With kind regards
Sabine Fahrendholz
Senior Product Manager

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``````+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 901
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_1' TITL 'Title of envelope' !
ACT 'L1'  SUP ALEX GAMU 1.15
ACT 'L2'  SUP ALEX
ACT 'L3'  SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END

+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 902
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_2' TITL 'Title of your env'
ACT 'L1'  SUP ALEX GAMU 1.15
ACT 'L2'  SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END

+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 903
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_3' TITL 'Title of your env'
ACT 'L1'  SUP ALEX GAMU 1.15
ACT 'L3'  SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END

+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 904
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_4' TITL 'Title of your env'
ACT 'L2'  SUP ALEX GAMU 1.15
ACT 'L3'  SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END

+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 905
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_5' TITL 'Title of your env'
ACT 'L1'  SUP ALEX GAMU 1.15
ACT 'L2'  SUP ALEX GAMU 1.15
ACT 'L3'  SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END
``````

Combining all

``````+prog maxima urs:27 \$ ULS envelope
ctrl warn 18  ! nonlinear envelope

sto#comb 906
Comb #comb base #comb*100 EXTR DESI TYPE 'UL_6' TITL 'Title of your env'
ACT 'UL_1'  SUP ALEX
ACT 'UL_2'   SUP ALEX
ACT 'UL_3'   SUP ALEX
ACT 'UL_4'   SUP ALEX
ACT 'UL_5'   SUP ALEX
SUPP #comb MAMI NODE P,UX,UY,UZ TITL 'Title of your env'
SUPP #comb MAMI QUAD M,VX,VY,N TITL 'Title of your env'
SUPP #comb MAMI QNOD M,VX,VY,N TITL 'Title of your env'
END
``````

I would achieve it like this. UL_6 would be your final envelopes, with the previous envelopes inside.
Make sure that you use correct SUP, and that your loads are tied to the correct actions. Ofcourse run your ASE of LC before Maxima. Adjust GAMU/GAMF etc. accordingly.

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