Hi all,
I am having a moving load generation which create hundreds of load cases. As a results, I have to create a lot of load combinations/ repeat loads, this slows down the analysis tremendously.
I wonder that can we create a envelope of all the load cases created by moving load generation and then use this envelope in other load combination. Any suggestion to workaround with this situation in Staad Pro. Thank you very much for your advice.
Here are a couple of options
You can filter any of the postprocessing tables based on the generated combination cases by right clicking on that appropriate table and choosing Results Setup. So if you filter the data inside the Summary tab for example for just the generated combinations, you can figure out which generation( or generations ) are the most critical. Subsequently you can only combine those generations with other cases.
Alternately you may use a LOAD LIST command to include only those generated combinations and then use the PRINT MAXFORCE ENVELOPE command as shown below to find out the envelope for each member. This would help in figuring out the worst generated case or cases for the critical members and you may then combine those generations with other cases
LOAD LIST 2 TO 11
PRINT MAXFORCE ENVELOPE
On a different note, I am sure you know of the ADD LOAD option that can be added as part of the moving load generation to combine other loads with the moving loads. That may help in avoiding defining additional REPEAT load cases/combinations. It would generate as many loads though but you will not need to create separate cases to combine the generations with other cases.
A sample model with LOAD LIST explained above and also with the ADD LOAD option is attached for reference.
Max_force_Moving_Load.STD
Thank for your support Sye,
So basically, we have to make engineering judgement to select the critical load cases by ourselves. This may base on some criterion like beam bending moment (+/-), pile axial forces (compression and also pull out force),... as what I am doing in a sea port project. This takes a lot of time and may not cover all the critical cases. Some other software which I used before allow us to envelope all the moving load cases into one envelope case (envelope results actually) and then we can use this envelope case combined with other load cases (live load, dead load with relevant combination factors). This is the best way to deal with the situation, automatically and exactly. Hope we can do that in near future with Staad Pro.
Sir.. Did you find any solution later ?
As I explained in my post from 2018, you would be able to generate an envelope out of all the generated load cases. You can then combine only those critical load cases out of the envelope with the other loads and that should help in limiting the number of combinations.
Yes but if the critical load cases vary everytime then i have to change the combinations right !
In few similar softwares this option of making envelope in a combination is available. Thats y i asked.