1. Provisions for confinement reinforcement in the 1997 ACI Building Code and the 1976 Uniform Building Code are based on criteria primarily related to increasing concrete strain capacity and retaining compressive strength of the core. The volume of required hoop reinforcement was devised to provide the same average lateral stress in the rectangular core as would exist in the core of an equivalent circular spiral compression member. For boundary elements of structural wall, design criteria should also be based on hoop size and spacing to delay inelastic bar buckling, contain the concrete core, and provide shear capacity.