Strange result

[andrea_pontiggia]

Do not understand why in this table of the reactions, all static loads have a check equal to 0, while the modal analyzes show a check equal to the double of the reactions.

The actions have the same sign of the reactions.

How is this possible?

Thanks

PS: Robot version 2013.

[Rafal.Gaweda]

File please

[Pawel.Pulak]

Andrea,

if these are seismic or spectral load cases and dominating mode was not set for them then such effect is justified. The information about sign was lost in quadratic combinations so forces and reactions have the same sign.

Similar topics were discussed before.

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Regards,

[andrea_pontiggia]

I attach the file: http://we.tl/4V7AWBgGd6

How do I know which is the dominant mode quickly?

And how can I assign it to a Robot?

I can not find the factor of participation of the masses in%.

Where can I find it?

Thanks

[Rafal.Gaweda · Accepted solution]

How do I know which is the dominant mode quickly?

Are you sure to use elastic supports for Dynamic analysis?

(if you block springs you will get 88% of massesin X dir in 1 mode and 77% masses in Y dir in 2 mode ; of course your decision)

And how can I assign it to a Robot?

Keep in mind that you have defined different modes filter for OBE-H and OBE-V+SMS cases

Screen shot above corresponds  to OBE-H cases

For other ones different dominant mode numbers 

I can not find the factor of participation of the masses in%.

 See first screen shot.