Bond Strength of neat grout to Smooth steel pipe

[DaveSar]

Hi,
I'm working on a support of excavation design for a 35' cut.

The design shows a 16" dia (10ft sections w/threaded joints) minipile "MP" with 10' bond length. They are considering inserting a 12" x 0.5" steel pipe (full length) inside the 16" dia MP as reinforcement and also to resist uplift forces. What bonding strength can be assumed between the grout and the 12" steel pipe?

 

[HTURKAK]

- I will suggest you to use 15 psi ( allowable axial load transfer stress btw grout and steel surfaces )

- If necessary, use shear keys to increase the transfer stress.





Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[Tomfh]

Assuming 10% bond strength compared to deformed bar is conservative.