ZEMCH 2019 International Conference Proceedings April.2020 | Page 159
1. Introduction
Recent earthquake events in Korea have increased the need for seismic assessment and design of
existing and new structures. The previous studies have shown that reinforced concrete columns offer
improved seismic behavior when designed with higher amount of confinement reinforcement. In
addition, research results show that increased volume ratio of reinforcing bar and the shape of the
reinforcement can improve lateral restraint and columns may exhibit more ductile behavior. In this
study, the effect reinforcement on performance of RC columns was experimentally investigated by
taking the shape and yield strength of transverse reinforcement as main parameters.
2. Experimental Program and setup
In this experimental program, the effect of confinement reinforcement in RC columns was
evaluated under antisymmetric moment, shear and axial load. The main test variables were the
configuration and yield strength of transverse reinforcement. The ductility and energy dissipation
capacity of RC columns were assessed under axial and lateral loads acting simultaneously.
Table 1. Proportions of concrete mixture
f´ c
(MPa)
24
G max W/C
(mm) (%)
25
Proportions of concrete matrix (kg/m 3 )
s/a
(%) W C S G AD Slump
(mm)
49.7 48.5 82 214 872 936 69.3 120
Table 2. Properties of steel reinforcement
Specimens Diameter f y ε y E s Remarks
H‐F
KSS‐5
KSS‐7
KSS‐12 D10
D10
D10
D10 540
554
788
1328 0.0027
0.0028
0.0039
0.0066 200,000
197,857
202,051
201,212 Shear
Reinforcement
All Specimen D19 523 0.0028 186,586 Longitudinal
Reinforcement
Table 3. Detail of the specimens
Specimens
H‐F
KSS‐5
KSS‐7
KSS‐12
f´ c
(MPa)
22.4
f y
(MPa) f wy
(MPa) p w *f wy
(MPa) B
(mm) D
(mm) d
(mm) L
(mm) Axial
force ratio
523 540
554
788
1,328 2.54
1.84
2.77
4.7 450 450 400 1800 15%
2.1. Materials
The mixture design of concrete is given in Table 1. The maximum size of coarse aggregate was
25mm. Ready‐mixed concrete with a design strength of 21 MPa was used to manufacture the specimens,
as described in Table 1. Concrete cylinders with ϕ100 mm × 200 mm were manufactured in accordance
with ASTM C31/C 31M. The compressive strength of concrete was tested according to ASTM C39/C
39M.
Experimental Study of Reinforced Concrete Columns with Confinement Effect
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