Civil Engineering Association

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hello, Juice, Yasir,
Can you explain to me from where etabs 9,5 take values to the variables Pu, Mu and Vu to design piers elements in shear ?
regards,
jcmas

They are simply design forces at top and bottom pier sections (for every floor).
They depend on defined Load Combinations used as a design Combination for Shear Wall Design - Design/Shear Wall Design/Select Design Combo.
After successfull analysis run you can view Wall Forces via Display/Show Tables/An.Res./Wall Output/Wall Forces, or via File/Print Tables/Shear Wall DEsign/Detailed Output.

After design you can view in addition Shear Wall Design Forces by Display/Show Tables/An.Res./Wall Output/Wall Design Forces.

(05-29-2009, 11:56 PM)JCMAS Wrote: [ -> ]hello, Juice, Yasir,
Can you explain to me from where etabs 9,5 take values to the variables Pu, Mu and Vu to design piers elements in shear ?
regards,
jcmas

Hi jcmas, VCHFCE answered your question right. Nevertheless, please don't let ETABS do the whole design process for you. I would suggest you pick out the design loads from ETABS analysis and design your pier elements using Excel spreadsheet following the code requirements--e.g., for flexural capacity of our wall (inplane or out-of-plane) stress-strain compatibility analysis will be an interesting engineering "brain" exercise. ;)

I hope this helps.

Regards,
juice

To all,

To answer most of your questions here, rather than exchanging ideas of which you are not so sure also if you are doing the right thing in ETABS I suggest you buy the following books from CSI everything is explained on how to model and design multi-storey building. I bought the last two books recently but I have not enough time to go through all of it yet. In production I'm still using Staadpro but start learning etabs and Sap2000 also.

http://orders.csiberkeley.com/SearchResults.asp?Cat=4

(07-14-2009, 06:39 PM)ammar.2520 Wrote: [ -> ]thannnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnks

Dear Ammar.2520:

Hi all,
How do you model transfer beam in etabs? Is it model as a shell element or only normal beam element?
The transfer structure consist of transfer beam with shear wall above the beam and column below the beam.
Can I only model the wall as a shell element and the rest (column and beam) as a beam/line element ?

Thanks.

Which is the fundamental period of the structure in Etabs out of the, say 100, that it produces?

(02-05-2009, 01:18 PM)aslam Wrote: [ -> ]Hello everybody,

Is it possible to define & design Boundary element (size larger than regular wall) in shear wall in etabs?

Yes it is possible, you define the boundary elements as columns, of the size you want, with the same pier name as the one you used for the wall, then ETAB will take the as a shear wall with boundary elements. Hope this help you.

(08-01-2009, 07:59 AM)fashion Wrote: [ -> ]Which is the fundamental period of the structure in Etabs out of the, say 100, that it produces?

Fundamental period can be misleading if you don't understand what dof response you required. Many textbook said that fundamental period is the period of the first mode. Well it is correct if the structure is 2D and the response you want is in the horizontal direction which is mostly example in the books for rigid beam plane frame under lateral earthquake.

In 3D structure with rigid diaphragm with 3 floor dof then there will be 3 fundamental period and of course you have to see the mode shape in which dof it moves then the period of the mode is the fundamental period in that dof direction.

Another interesting problem is as follow. If you want to design a transfer beam or cantilever beam under vertical earthquake excitation and this beam is part of a whole large structure what is the fundamental period for vertical response spectrum? Our professors had no idea of what is the fundamental period because of the associated fundamental period only to 1st mode of all those mode periods of the structures.

I would suggest you to ask people who main works is in vibration they are the one who invent this modes and fundamental period things :D

essenza, thanks for your answer, the main reason for my question is to know the fund. period of the structure so as to manually calculate the seismic forces (i.e. base shear) so as to hand check the results from etabs. I know i can aproximate the period with the formulas, but eigenmode analysis is kind of precise.