minimum closed stirrups for torsion

huangyhg

minimum closed stirrups for torsion
from aci sec. 11.6.1 torsion can be neglected if tu is less than (phi)(f`c)^.5(acp^2/pcp).  
say if my tu is less than the above value, but i still want to place closed stirrups because torsion is present, is there a minimal standard size that is acceptable to use?
thanks
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since additional torsional stirrups are not required in this case then using the minimum stirrups required for shear as closed stirrups would be adequate.  
i concur with willisv, but with the following additional point:  use closed ties, or stirrups with an added closing top bar, not just stirrups alone.  this is required for torsion resisting ties.
regards,
chichuck