ETABS - 3 Story Mixed Use SCBF structure - ETAB Question.

[EngineeringAdam]

Hello all.

This is my first post here so please be gentle!

I have 3 story mixed used SCBF structure that I am modeling in
ETABS. This being my first attempt using ETABS I am learning
quite a bit.

Anyway, my question involves the master story (3rd floor). It
is wood framed with shear walls sitting atop 2 more floors of
concrete deck with SCBF's for lateral resistance.

I have little problem getting the first two stories into the
model - but I am unsure of what to do for the wood framed master
story.

I tried adding wood into ETABS' materal properties and then
creating wood beams and diaphragms - however, I don't think this
is working so well.

What is the preferred method of modeling a wood master story in
ETABS?

Should I just add Mass Areas for the wood structure's foot
print? What about the hold down force from the wood shear walls?


Any help would be MUCH appreciated.

Thanks,

Adam

 

[msquared48]

Sounds like you need to use the top concrete floor, the podium slab, as the seismic base. I believe ETABS is primarily for concrete applications, not wood. That's what those who use it tell me. I don't.

Figure out what the lateral force is for the wood system and apply that as an additional lateral force at the podium slab. As for the holddowns in the wood story, I do not see that as a problem, if there will be any holddowns at all for only one level of framing.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask