This estimate has a number of small errors. 1. The plinth beams should overlap at the corners and be tied to each other. So, for a 9 " × 9" corner intersection, the short side beam should be 13.5 ft long and not 12 ft long, while the long side beam length is correct at 14 ft. Therefore, total plinth beam main rebar length is 2x13.5 + 2 x 14 = 55 ft, not 52 ft. Furthermore, the main reinforcement bars may require a hooked anchorage at each corner end, adding about 1ft at each end of each main reinforcement bar, making the 13.5ft bar length about 15.5ft and the 14ft bar length about 16ft. 2. The shear reinforcement stirrups should have shorter spacing towards the corners and wider spacing towards the centers, and each stirrup would have extra length of about 0.5ft for the hooked overlap connections to the main reinforcement bars. All of these extra rebar lengths add up to a significant extra amount of rebar.
