Rebar Stress 1

[BS8110]

Folks,

In 'Notes on ACI 318-08' P6-31 the bar area calculation for tension and compression reinforcement uses different steel stresses e.g. 60 and 58.7 psi.

Does anyone know the reason for the two stresses or is it a typo?

many thanks

 

[JAE]

Not a typo - the compression steel is strained to a lower strain (I have the 05 version but in it the compression strain is .00202)

The beam is designed for the compression strain in the concrete at the top of the beam at 0.03. Since the top bars are a bit lower, the strain there is lower. Thus the bars are not stretched to their full 60 ksi.

 

[dik]

Reinf is often spec'd as 400 MPa... which when hard converted comes out to 58 something... it's, for practical purposes, equivalent to Grade 60...

Dik