Any tips for generating combinations ?

[Anonymous]

Hi to all,

I would appreciate some advices for effective generation of All necessary combinations for structural analysis of building.

I'm trying to generate a combination list for 3d frame model. There's 2 DL, 1 Snow, 3 Winds, 2 Seismics (and 2 moving Live load cases which I would exclude from this topic). When I generate with option: Loads/AutoComb/ManCombGen/ More/ Next - check all default combs that program offers, then from some reason Snow wasn't generated in any of combinations. What I need to add is:1 comb with S and DL; 3 with Snow, Dead and Winds and 4 combs with Snow, Dead and Seismics. When I try with option: Loads/ManCombs/ add wanted cases then click new and name it - program adds that combination to falling menu of combs above, but it cannot be seen in combTable and further after Calculations and RC Members req.reinf mode,can not be selected for designing members.

[Artur.Kosakowski]

Hi @Anonymous

Could you attach your model?

[Anonymous]

Ofcourse, here it is rtd file

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

You need to restore the missing relations for snow nature:

 

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Anonymous]

Hi @Artur.Kosakowski,

I had manage to manually generate these combinations. The problem was the order of clicking options (1. new 2.naming and choosing comb.type 3.inserting wanted cases with their coefficients). If its done in oposite direction program overwrites some of old (automatic generated) combinations.

Now there is new manually generated combinations in the table and there are available for RC design.

In comb.table there are columns combination type and case nature which purpose is a bit unclear to me. (see attachment) For automatic generated combs combination type column is empty and for manually generated user must define it, so I chose appropriate types. Also for auto-combs case nature was dead by default and for manual-combs dead nature can not be chosen so I chose structural and seismics. Have I done this right? What is the influence of these parameters? 

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

They are irrelevant unless you want to use the combination is automatic generation of manual combinations. In such case they will get the corresponding load factors.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[Anonymous]

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@Artur.Kosakowski wrote:

Hi @Anonymous

You need to restore the missing relations for snow nature:

 

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

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Arthur, can you set the load factors for this auto generation? say i want 1.2D+1.6LL or 1.4D+1.6LL??

[Artur.Kosakowski]

Hi @Anonymous

This is governed by the selected regulation. Which code are these rules from?

[Anonymous]

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@Artur.Kosakowski wrote:

Hi @Anonymous

This is governed by the selected regulation. Which code are these rules from?

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I see, soo you can not modify the automatic load combination generator of Robot?

[Artur.Kosakowski]

HI @Anonymous

You can edit / create a new regulation file.

See: 

https://forums.autodesk.com/t5/robot-structural-analysis-forum/how-to-define-and-use-newly-defined-load-case-subnature/m-p/7300896

https://forums.autodesk.com/t5/robot-structural-analysis-forum/user-automatic-load-combinations/m-p/5652734

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.