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Structure with really small period

6 REPLIES 6
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Message 1 of 7
TSOFA
316 Views, 6 Replies

Structure with really small period

Hi, I have a structure (like tower) which is a staircase and lift shaft. I designed the structure as you can see at the link bellow but it seems that the period is really small ( 0.74sec for the first mode and 0.54 for the second mode which activates 60% of the mass) for such a slender type of structure. 

Does this seems right to you??

 

 

http://we.tl/lZjV9YdQGk

 

 

6 REPLIES 6
Message 2 of 7
TSOFA
in reply to: TSOFA

I also added a slab foundation to the structure and I find that is very strange that for the same foundation (comb 16- seismic foundation) the base pressure is always possitive but at the results of the sattlements I have uplifting effects!!

Message 3 of 7
Rafal.Gaweda
in reply to: TSOFA

Check , change local Z direction of this panel


Rafal Gaweda
Message 4 of 7
TSOFA
in reply to: Rafal.Gaweda

of which panel?
Message 5 of 7
Rafal.Gaweda
in reply to: TSOFA

" slab foundation to the structure "


Rafal Gaweda
Message 6 of 7
dimogrec
in reply to: TSOFA

f1=1.36Hz seems ok to me for this kind of structure. In my opinion your structure has many bracings so it isn't so slender...

Message 7 of 7
TSOFA
in reply to: dimogrec

can you explain the pressure- settlements results? they don't seem to match with each other

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