jpmm - a piece of rope is always twice half its length. I'm surprised at you!
pgaviria - what kind of pier are we talking about: building, highway or marine application? The minimum shear reinforcing requirements are different depending on the applicable code and of course the location of said pier in regards to seismic zones. Be more descriptive.
ACI 318-89 11.5.5.1 requires a minimum shear reinforcement when Vu exceeds one half the shear strength provided by the concrete Phi*Vc.Do this apply to Drilled pier foundations? How deep in the pier should this ties go?