Mass participation factor. Imposible to approach 90%

[StructuralSilver55]

I am having some difficulties when I try to reach 90% of mass at least in 1 direction, to do a seismic a analysis of the structure. I tried to find it but as you can see in the attached picture . Thank you very much for your help. File attached

[Artur.Kosakowski]

As it is a slab the vertical vibrations are what you may expect to be the dominant factor. Try to switch off the vertical mass.

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[StructuralSilver55]

Thanks Artur, I've read in other post that it's not necesary to reach 90% of total acumulated mass in one direction, it's only a recomendation. I've done another analysis with 100 modes and still the structure hasn't 90% of the mass...

[Artur.Kosakowski]

To be honest I'm not sure what is your objective as 90% in horizontal directions seem to be intended for a building (vertical cantilever) rather than for a slab that vibrates in the vertical direction.