INVESTIGATION OF RC COLUMN CONFINED BY RECTANGULAR SPIRAL REINFORCEMENT THROUGH THE USE FINITE ELEMENT ANALYSIS

Abstract

The non-linear stress-strain behavior of square reinforced column confined by rectangular spiral lateral reinforcement subjected to axial load is investigated numerically using abaqus. Twenty nine (29) short square RC columns are modeled where fifteen have conventional hoop tie and the remaining fourteen columns have rectangular spiral configuration. In addition to configuration of lateral reinforcement, the amount and spacing of the lateral reinforcement are included as a factor of confinement in the investigation. The amount of reinforcement ratio adopted for this work is less than 2%; however out of total five groups, RC column models in one group are detailed with the amount of reinforcement ratio for comparison. The lateral reinforcement spacing is expressed in terms of the ratio of spacing to core dimension (s/dc). The primary objective this study is focused on the confinement effect of lateral reinforcement configuration in terms of stress carrying capacity, deformation capacity and non- linear stress-strain behavior of confined concrete. The analysis results clearly indicate that confinement of lateral reinforcement with both configurations enhanced the deformation capacity than the stress carrying capacity of the investigated square RC column. For RC column confined with the amount of reinforcement ratio in the range of 1.6%-2%, spacing the lateral reinforcement in such a way s/dc ratio in the range of 0.4-0.5 has resulted in 12% and 40% higher deformation capacity in hoop and spirally tied RC column members respectively. For these mentioned RC columns with the same amount and spacing of lateral reinforcement, the stress capacity improvement is 2% higher compared to the RC column member in which tie the spacing is greater than 60% of the core dimension (or s/dc≥0.6). Thus, for amount of reinforcement in the range of 1.6%-2% the rectangular spiral confinement configuration has more significant enhancement on the deformation capacity compared to the conventional rectangular hoop tie confinement. Furthermore, from the analysis result it is inferred that the spacing of lateral reinforcement on RC column should not exceed half of the core dimension (or s/dc ≤ 0.5) of confined concrete. Accordingly, the use of rectangular spiral reinforcement as lateral reinforcement can be considered as a better alternative to lateral reinforcement of square RC column.