The column dimensions were 10 in. in the north-south direction (denoted as y-direction on the confined concrete column cross-section) and 15 in. in the east-west direction (denoted as x-direction on the confined concrete column cross-section). A concrete cover of 0.75 in. was used on all sides of the confined concrete column. Eight ASTM A706 Grade 60 #7 deformed steel bars were used for the longitudinal mild steel reinforcement bars inside the confined concrete of the column. The selection of ASTM A706 reinforcement bars were based on the recommendations of ACI 318-11 Code Section 21.1.5.2. The longitudinal mild steel reinforcement bars were extended in the entire column height (i.e., 104 in.). The longitudinal mild steel reinforcement bars …show more content…
Figure 3-5 shows the confinement hoop-pair that was comprised of two same size confinement hoops one on the top of another. Each confinement hoop measure 9.75 in. x 8.50 in. center-to-center. As shown in Figure 3-7 and Figure 3-8, the confinement hoops were tied to the eight longitudinal mild steel reinforcement bars in the column. The confinement hoops for the entire confined concrete column were fabricated using ASTM A615 Grade 60 #3 deformed steel bars. The confinement hoop sets at the column were spaced at 2 in. center-to-center along the entire 104-in. height of the confined concrete column except for the 20 in.-long testing region where the confinement hoop sets were spaced at 2.25 in. center-to-center. The first confinement hoop set for the testing region, Hcr, was spaced at 1.125 in. from the center (i.e., mid-height) of the confined concrete column corresponding to a center-to-center spacing, s, of 2.25 in. between the confinement hoop sets in the testing region. A total of 10 confinement hoop sets were used in the testing region. The hoop spacing, s, of 2.00