Diaphragm/Shear Wall Forces with vertical combinations

[paudel09]

I have a four-story building with shear walls on upper floors, and Ordinary moment frame at the first floor (please see attached picture). This results in the first floor (including the shear walls) to be designed for R=3.5 as per ASCE 7-16 Section 12.2.3.3. For the shear wall forces, I will increase the forces as shown in the picture. For the diaphragm forces, do I calculate Fp2*6.5/3.5 and compare it to increased Fx at Level 2? I was thinking that as long as diaphragm forces is governed by Fx rather than Fpx, that I should not have to increase Fp2 to compare at all. I am not sure I explained it well. Thank you in advance.

 

[m_struct]

Hi. Thinking about the load path at the L2 diaphragm . .. . Is this a rigid diaphragm? Have you considered the deflection capability at L1 of the concrete shear wall (very stiff) and the OMF (flexible)? When L2 rigid diaphragm is pushed the loads will be distributed based on stiffness. I would expect there to be a large transfer force in the diaphragm at L2 from the internal shear walls to the external shear walls. Could the moment frames go up the full height of the building, with a higher ductility to match that of the concrete shear wall?

 

[paudel09]

m strut,

The diaphragms are all flexible, and shear walls at the first floor is CFS and not concrete shear walls. Moment frame could potentially extend full height, however that would result in the upper floor shear walls to be designed for R=3.5 doubling the design force, which I feel is unnecessary.