bar and cover tolerance

[boffintech]

ACI 318 d = distance from extreme compression fiber to centroid of longitudinal tension reinforcement, in.

ACI 318 7.5.2.1 — Tolerance for depth d, and minimum concrete cover in flexural members, walls and compression
members shall be as follows:

(see table)

except that tolerance for the clear distance to formed
soffits shall be minus 1/4 in. and tolerance for cover
shall not exceed minus 1/3 the minimum concrete
cover required in the design drawings or specifications.

Can anyone give a less complicated explanation of d and what the tolerance means. I think it means the depth from the top of the beam to the center of the bottom bars.

Also, how can the tolerance for d have a plus and minus but tolerance for cover only have minus?

 

[Commandant]

I would not concern myself with the placement tolerances. All the tolerances are doing is limiting the erector from making a poor concrete section that will not behave as designed. Just use a "d" from the extreme compression fiber to the centroid of your steel.

A soffit is the underside of a structural component. Like the underside of a canopy.

 

[boffintech]

Explain the material as an inspector would use it, not a designer.

 

[TDAA]

The location of the stel could be up or down. One increases your cover, the other makes it less. The minimum cover insures just that, a minimum. If you have more, that is OK, from a cover standpoint.