Table 2 gives the properties of four types of reinforcement , where the D19 ( 286.7 mm 2 ) re‐bars with a yield strength of 523 MPa were used as the longitudinal reinforcement of the specimens . the transverse reinforced used in test specimens of this study were D10 ( 71.3 mm 2 ) bars with yield strength of 540MPa , 554 MPa , 788 MPa , and 1328 MPa .
2.2 Specimen details
As shown in Fig . 1 , all tested column had cross‐section of 450 × 450mm and a total height 2,700mm . The test region was 1,800mm long . The test specimens were designed to have strong stubs at both ends with dimensions of 1200 × 450 × 400mm and 1400 × 450 × 400mm as top and bottom stub , respectively . Both the stubs were heavily reinforced in order to avoid any deformation outside the test region . The 14‐D19 deformed bars were used as longitudinal reinforcement . All test specimens contained hoops and spiral reinforcement as transverse reinforcement . A constant axial force ratio 15 % of used throughout the test .
D10 D19
D10 D19
125
D10 @ 125 135 Degree Hoops
125
D10 @ 125 ( Spiral Re-bar )
2.3 Test Setup and instrumentation
( a ) H-F ( b ) KSS Figure 1 . Details of specimens ( Unit : mm )
The test specimens were subjected to reversed cyclic bending , shear and axial load by setting up vertically with fixed top and bottom stubs using a hydraulic pressure system . The lateral force was applied to the loading frame connected to the upper stub . The lateral force actuator with loading capacity of 1000 kN , was so located that point of contraflexure is produced at the midspan of specimen . In order to keep the upper stub on the same level during lateral movement , a restraining frame was installed in the loading frame . Fig . 2 ( a ) presents details of the loading and meausrment system . In order to measure the drift angle of specimens , several linear variable displacement transducer ( LVDT ) were installed . Two LVDTs of 300 mm were installed on the upper and lower stubs of the specimens , and the measurements were taken as average to calculate the drift angle . the strain in transverse and longitudinal reinforcement was measured used strain gauges attached on the rebar surface . Fig . 2 ( b ) shows the loading protocol used in this testing program . The specimens were loaded monotonically up to the first yield drift angle , δδ � , followed by a series of drift‐controlled loading cycles comprising two
149 ZEMCH 2019 International Conference l Seoul , Korea