CMU columns in Seismic Design Cat D

[shacked]

I have designed a sports court with a regulation sized basketball court for a residential client on the same lot as his custom home. All 4 walls of the rectangular sports court are 12" thick fully grouted CMU and they are 25ft tall from footing to top plate, with no intermediate support.

Long story short, due to numerous openings in the walls I am designing the Special CMU shear walls also as pilasters to transfer the out of plane shear loads of the lintels running over the top of the openings into the fdn and roof diaphragm. The pilasters are 6ft in length and I detailed them with #3 ties @ 8" o.c. vertical so that no unsupported vertical will be farther than 6" away from a laterally supported vertical.(ACI 530-05 2.1.6.5)

Unfortunately that is hard to build and the contractor wants to provide one large tie to span the length of the pilaster with #3 "mustache" ties @ every other vertical. I am having trouble with this since the code says that for compression members "no bar shall be farther than 6" clear on each side along a lateral tie from such a laterally supported tie.)

Please see attached details.

Any thoughts or clarification of this portion of the code would be greatly appreciated.

 

[CELinOttawa]

I wouldn't allow the change.... Far less confinement, and in reinforced concrete and masonry design for seismic, confinement is key. I much prefer your detail.