From: "Sprague, Harold O." <SpragueHO(--nospam--at)bv.com>
Date: Mon, 7 Feb 2000 11:56:48 -0600
Reference UBC 1629.6.5. 2.
There are several ways to check the moment frame depending on your model.
Ultimately you need to isolate the moment frame and proporptionately
increase the forces on it to where they generate a base shear on the moment
frame of at least 25% of the dual system structure base shear force.
> -----Original Message-----
> From: satd(--nospam--at)techie.com [SMTP:satd(--nospam--at)techie.com]
> Sent: Monday, February 07, 2000 11:06 AM
> To: SEAOC
> Cc: satd(--nospam--at)techie.com
> Subject: Design of RCC Dual Systems
> Hello everyone:
> I am designing a reinforced concrete frame shear wall (dual) system in
> Seismic Zone 4. The frames are SMRFs.
> I am using UBC-1997, FEMA-302 and ACI318 for design of these systems.
> For dual systems, FEMA 302 requires - "The moment frame must be designed
> to have a capacity to resist at least 25% of the total required lateral
> seismic force ..."
> The system is 10 story tall with 3 equal bays. The middle bay is the
> shear wall and the outer two bays are SMRFs. In other words, the frame
> and the shear wall exist in the same vertical plane. I have modelled the
> shear wall using beam-column elements (i/c. shear deformation in the
> analysis). I have also modelled the thickness of the wall using rigid end
> zones at the ends of the beams at each story level. I have performed an
> usual 2D-ELF analysis of the whole system.
> How do I impose the 25% rule to the design of the SMRFs as required by
> FEMA302? Also, does this requirement exist in any particular section of
> the UBC?
> Any help and or suggestion in this regard will be appreciated.
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