The maximum vertical spacing of the special boundary element transverse reinforcement in the flange is equal to the following:

ACI 318-19 (18.10.6.4(e))

ACI 318-19 (Table 18.10.6.5(b)

Thus, use vertical spacing s = 4.00 in.

In the equation for s_o, the maximum center-to-center spacing of the laterally supported longitudinal bars, h_x, is equal to approximately 11.17 in. assuming #5 transverse reinforcement confining all the longitudinal bars in the flange.

For confinement of the flange in the direction of analysis, b_c = b_c,1 = 214.5 in.

ACI 318-19 (Table 18.10.6.4(g))

With #5 overlapping hoops and #5 crossties engaging all the longitudinal reinforcement in the flange, provided A_sh = 20 × 0.31 = 6.20 in.² > 5.79 in.².

Use #5 hoops and #5 crossties around all the longitudinal bars spaced at 4.0 in. on center in the flanges.

The maximum vertical spacing of the special boundary element transverse reinforcement in the web is equal to the following:

ACI 318-19 (18.10.6.4(e))

ACI 318-19 (Table 18.10.6.5(b)

Thus, use vertical spacing s = 4.00 in.

In the equation for s_o, the maximum center-to-center spacing of the laterally supported longitudinal bars, h_x, is equal to 10.07 in.

ACI 318-19 (Table 18.10.6.4(g))

Where a vertical spacing of 4.0 in. is used in the web to match the vertical spacing of the transverse reinforcement in the flanges.

With a #5 hoop and one #5 crosstie, provided A_sh = 3 × 0.31 = 0.93 in.² > 0.61 in.²

In the direction perpendicular to the direction of analysis, b_c = b_c,2 = 24.0 in.

ACI 318-19 (Table 18.10.6.4(g))

With a #5 hoop and two #5 crossties, provided A_sh = 3 × 0.31 = 0.93 in.² > 0.65 in.² (one of the hoop legs is in the flange, so the area of that leg is not included in the provided area of transverse reinforcement).

Use a #5 hoop and #5 crossties spaced at 4.0 in. on center in the web.