중심 압축하중을 받는 RC 기둥에서 V형 보조띠철근의 횡구속 효과

Abstract

This study proposed a simplified supplementary tie arrangement method in reinforced concrete columns using V-shaped bars as an alternative to the crossties specified in ACI 318-11 provision. Eight RC column specimens were prepared to examine the effectiveness of the V-ties on the compressive performance of columns and concrete confinement. The test parameters investigated were the type of supplementary ties, the amount of transverse reinforcement, and concrete compressive strength. Test results showed that the axial capacity of V-tie columns can be conservatively estimated using ACI 318-11 equations. With the spalling of the concrete cover, 90-degree hooks of crossties were gradually opened, whereas no V-ties were extracted from core concrete. As a result, higher axial ductility ratios were obtained for V-tie columns than for the companion crosstie columns. This trend was more notable as the amount of transverse reinforcement decreases and concrete compressive strength increases. Ultimately, a greater effective confinement pressure is obtained in V-tie arrangement than the conventional crosstie arrangement.