For Longitudinal spacing, s between the legs of shear reinforcement is given by¹;

IF

V_u - φ*V_c ≤ φ*0.33* f`_c^0.5 *b_w*d metric-units

φ*4* f`_c^0.5 *b_w*d US-units

THEN

s_min,u ≤ s ≤ MIN[0.5*d, 600mm (24in.), s_max,u]

ELSE

s_min,u ≤ s ≤ MIN[0.25*d, 300mm (12in.), s_max,u]

where

s_max,u = the maximum longitudinal spacing specified by the user

s_min,u = the minimum longitudinal spacing specified by the user

Moreover IF compression reinforcement is required the compression reinforcement shall be enclosed by ties². This is an additional limit, not an alternative.

Vertical spacing of ties is then given by³;

s ≤ MIN(16*d_b, 48*d_b,w, b_w, h)

where

d_b = the nominal diameter of the bar

d_b,w = the nominal diameter of the link reinforcement