What is PBV? 1

[carnahanad]

Hello,

I'm a structural engineer and two electrical engineers showed me a detail of their generator pad that had a note that read something like, "...95% proctor test or 55psi PBV." Can anyone tell me what PBV means?

 

[Ron]

It is probably a reference to a "plate bearing value". The specification is poor in that the two parameters refer to two completely different things....the "95% proctor test" should read something like: Compaction under the pad shall achieve at least 95% of the maximum dry density as determined in the laboratory by the "Modified Proctor" method (ASTM D1557).

The 55psi PBV should be stated something like: the bearing soils shall have a minimum bearing/penetration resistance of at least 55psi when determined by (whatever test should be referenced in your area).

The first reference is to in-place compaction or density, while the second reference is a material stability criterion.

 

[carnahanad]

Ron,

That makes a lot of sense! I really appreciate the input!

 

[dgillette]

If PBV means plate bearing value, 55 psi seems like pretty soft stuff, something like standard proctor 3-4 points wet of optimum, or bearing capacity failure under the heel of a large man's boot and deep ruts under a bicycle tire.

See pp. 17-23:

http://www.usbr.gov/pmts/writing/earth/earth.pdf

Regards,
DRG