HIGH-STRENGTH CONCRETE COLUMNS CONFINED BY RECTANGULAR TIES

This paper presents an experimental study of the behavior of large-scale high-strength concrete columns confined by rectangular ties under concentric loading. Effects of key variables such as the concrete compressive strength, the tie yield strength, the tie configuration, the transverse reinforcement ratio, the tie spacing, the longitudinal reinforcement ratio, and the spalling of the concrete cover are studied in this research program. The behavior of high-strength concrete columns is characterized by the sudden separation of the concrete cover, leading to a loss of axial capacity before the lateral confinement becomes effective. After the concrete is completely spalled, important gains in strength, toughness, and ductility are recorded for the concrete core of well-confined columns.