Brandon
Civil/Environmental
- Oct 16, 2000
- 29
In AASHTO 8th Edition, Equation 5.6.4.6-1:
rho=(4Asp)/(dc*s) >/= 0.45(Ag/Ac-1)(f'c/fyh)
does anyone know for certain if the term "Asp" is meant to be just the area of a single bar of the size being used for the spiral, or is it twice that (i.e. "2 legs" as for shear reinforcing)? I have a 42" drilled shaft with 6" clear cover to the spiral, f'c=4ksi, fyh=60ksi, and transverse reinforcing is not otherwise required for shear or seismic. It seems that this results in the core area (Ac) being small relative to the gross Area (Ag), which makes the second term of the above equation relatively large (0.0269), and I can't seem to get it to work for reasonable spiral bar size and pitch (I calculated that I would need #8 spiral with a 3.5-inch pitch which just seems absurd to me). If Asp is actually supposed to be 2x the bar area, this at least gets me to #6 spiral with a 4-inch pitch.
The reason for the 6" clear cover is that there is a smaller (36") rock socket below the portion of the drilled shaft in soil and the cage is just being extended up into the 42" shaft.
Thanks in advance.
rho=(4Asp)/(dc*s) >/= 0.45(Ag/Ac-1)(f'c/fyh)
does anyone know for certain if the term "Asp" is meant to be just the area of a single bar of the size being used for the spiral, or is it twice that (i.e. "2 legs" as for shear reinforcing)? I have a 42" drilled shaft with 6" clear cover to the spiral, f'c=4ksi, fyh=60ksi, and transverse reinforcing is not otherwise required for shear or seismic. It seems that this results in the core area (Ac) being small relative to the gross Area (Ag), which makes the second term of the above equation relatively large (0.0269), and I can't seem to get it to work for reasonable spiral bar size and pitch (I calculated that I would need #8 spiral with a 3.5-inch pitch which just seems absurd to me). If Asp is actually supposed to be 2x the bar area, this at least gets me to #6 spiral with a 4-inch pitch.
The reason for the 6" clear cover is that there is a smaller (36") rock socket below the portion of the drilled shaft in soil and the cage is just being extended up into the 42" shaft.
Thanks in advance.