The provided cross-section shows a Special Boundary Element at the edge of a concrete shear wall. What is the primary structural purpose of the closely spaced transverse confinement hoops shown in this boundary element?

• To increase the pure flexural tensile strength of the wall
• To provide confinement for the concrete and prevent buckling of longitudinal reinforcement
• To reduce the overall weight of the boundary element
• To serve as the primary shear transfer mechanism across horizontal construction joints