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PostPosted: Wed Dec 18, 2013 8:39 am 
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Joined: Wed Dec 18, 2013 7:58 am
Posts: 6
Hello

I've been designing a footbridge recently according to the eurocodes.

I created about 1400 loadcases of conditional live loads, and a few of other loads like temperature , shrinkage, dead loads , wind

Then I run the calculation and maxima works without a problem.
I decided to define more loadcases due to the vertical and horizontal acting of the crowd simultaneously.

After that I had:
gr1-1400 loadcases of only vertical acting
gr2-1400 loadcases of vertical+horizontal acting in the positive y direction
gr3-1400 loadcases of vertical+horizontal acting in the negative y direction

none of these groups above appears in one combination with another group

After that I define 3 seperate modules of maxima (with different groups of live loads acting conditionaly each) f.e.

comb 1 contains (1400 loadcases of only vertical acting) gr 1
comb 2 contains (1400 loadcases of vertical+horizontal acting in the positive y direction) gr 2
comb 3 contains (1400 loadcases of vertical+horizontal acting in the negative y direction) gr 3

every combination defined in seperate maxima !!

I run calculation and it acctualy stops at the first maxima, which had calculated in like 60 seconds before I defined more loadcases of the live loads which the comb 1 does not even take into consideration according to what I had defined.

To make it clear.
There is no error. It just takes ages to calculate while it took like 1 minute before I defined more loadcases in general count.

Second point after defining more loadcases each combination contains the very same number of loadcases as before ! The loadcases differ between the combinations though.

I'm asking for any clue, or solution? Maybe there is a limit for overall loadcase number which disturb maxima in its calculation or any limit of the number name of a loadcase.
It's very important to me as I defined the combinations manually and I have like 50 combinations defined. I have no time to calculate each maxima for like 10000 sec.

PS: I can send You the .dat file from TEDDY if needed. It's an educational project


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PostPosted: Wed Dec 18, 2013 2:29 pm 
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Joined: Wed Dec 10, 2008 1:35 pm
Posts: 78
Hi!

Maybe the database (cdb) is too big. The time effort for MAXIMA increases with the size of the database.

Sometimes it may help to clear the database and start the calculation from scratch. If your harddisk is fragmented this will also slowdown your calculation, especially with big databases.

gmay


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PostPosted: Wed Dec 18, 2013 4:19 pm 
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Joined: Wed Dec 18, 2013 7:58 am
Posts: 6
Hello,

Thank you for your reply

I guess you maybe right, with no doubt the size of the database increases when there are lots of loadcases.

"Sometimes it may help to clear the database and start the calculation from scratch. If your harddisk is fragmented this will also slowdown your calculation, especially with big databases."

Can you explain me how to do this? I'd like to check it out.

If you meant to delate all the sofistik files and run the calculation from the very begining, I have already tried that and unfortunately it didn't help.


I will still appriciate more clues. I'll write it down when I handle with the problem.


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PostPosted: Thu Dec 19, 2013 11:57 am 
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Joined: Thu Jan 17, 2002 7:21 am
Posts: 120
Hallo,

the computing time of MAXIMA depends on the number of load cases. When you have many load cases within the database, the computing time can be very long. Please note, that only numbers of the initial and resulting load cases are supported till 9999 in version 2012. Larger load case numbers are possible, however not guaranteed.
In the next major relase version 2014 (coming soon) larger load case numbers are guaranteed (till 999999). In addition, we have improved the performence in terms of the computing time.

It is also possible, that the computing time depends on the hardware. It may be, that the calculation is faster using an SSD disk.

With kind regards
Sabine Fahrendholz
Product Management


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PostPosted: Fri Dec 20, 2013 5:57 pm 
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Joined: Wed Dec 18, 2013 7:58 am
Posts: 6
Thank you for your reply Sabine.

Unfortunately I have no ssd disc. I'm pretty sure that might help but a little.

Since I had no time to wait anymore I decided to handle the problem reducing the number of loadcases 4 times.

from one loadcase per 0,5 m^2 to a loadcase per 1 m^2

As a result each maxima calculates like 10 seconds instead of 2000 sec.

Having that effect now I can tell that it's the general number of loadcases that matters the most.


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PostPosted: Fri Feb 03, 2017 11:55 pm 
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Joined: Fri Feb 03, 2017 10:39 pm
Posts: 3
Location: Ljubljana, Slovenia
Hello,

I had a simillar problem with Maxima taking unusual large amounts of time for calculation. The problem was in the report output (ECHO), where the ECHO had 'FULL' for the atribute. I changed it either with 'NO'/'TABS' or other atribute but in no way 'FULL', shown in the example below:

+PROG MAXIMA
HEAD Superposition
ECHO FULL
...
...
END

Best regards

Uros G.


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PostPosted: Mon Feb 06, 2017 10:50 am 
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Joined: Thu Jan 17, 2002 7:21 am
Posts: 120
Hello,
using the full printout it is possible that MAXIMA needs more computing time due to the printing routines. We recommend to use ECHO CHCK for the relevant results. When defining a special element in record SUPP item FROM, the full printout can be used, because here only the results of the defined element are printed. Nevertheless, we are working at a faster MAXIMA with ECHO FULL for version 2018.

Regards
Sabine Fahrendholz
Product Management


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