Interior vertical and horizontal rebars for pump foundation

[AskTooMuch]

Anyone got a good reference when to put interior vertical and horizontal rebars for pump foundation. Say pump foundation is 6'W x 12'L x 6"H. I mostly see just exterior rebars on all sides. But I think interior rebars are also used, I see this sometimes on bigger mass concrete pump/compressor block foundation.

 

[WARose]

For a 6" thick slab.....seems to me like you'd just have the normal horizontal steel (in both directions) everywhere. There is no room to develop vertical steel.

 

[AskTooMuch]

6 feet, it's a typo

 

[WARose]

For high pedestals/house keeping pads.....that's kind of a judgement call. For low unbalanced forces (stuff like pumps).....I will typically just use perimeter rebar. (And/or where ever there will be anchors/skid bearing. It winds up looking like wall reinforcement.) The rest is just fill to make forming easier.

However for big compressors generating tens of thousands of pounds of unbalanced force....I will wind up using that bar everywhere to hold it together and add mass.

I can't think of too many references that cover this. In fact, in most of them (I can think of), you see the perimeter approach.

 

[HTURKAK]

This subject is not clearly addressed in the codes . Assuming block foundation , a minimum reinf. for shirnkage and temp. ( 30 kg / m3) should be provided and this reinf. should be distributed in all three direction as perimeter reinf .cage.


In order to get an idea , i copied and pasted the following snap from
API RECOMMENDED PRACTICE 686

(....Although ACI 318 does not specifically address the required steel in a block foundation, the requirement of 0.18 percent
of the cross-sectional area of the concrete may be used as guidance for the amount of temperature reinforcing steel in a foundation using grade 60 reinforcing. In the event that a foundation size greater than 1.20 meters (48 inches) thick is required for stability, rigidity, or damping, the minimum reinforcing steel may be as suggested in ACI 207.2R, Effect of Restraint, Volume
Change, and Reinforcement on Cracking of Massive Concrete, with a suggested minimum reinforcement of 22.2-millimeter (#7) bars at 30 centimeters (12 inches) on center....)