Common strength of reinforcing & concrete in 1929 3

[SayGoodDay]

Hi Fellows

I am from Australia, I am doing a bridge rehabilitation project. The original design is from the Main Road Board in 1929. It doesn't show the grade of reinforing & concrete on the drawing.

So my question is, in 1929, what is the common reinforcing and concrete grade? (in MPa).

Thank you.

 

[LittleWheels]

BHP and Smorgen have historical information available on their websites. In 1929, it is likely that steel grades matched British steel (steel sections were shipped out).

Concrete could be anything.

Sampling and testing would be very useful.

 

[JStephen]

While grades may have changed, overall detailing has changed. For example, square bars or plain bars versus normal deformed bars. I've seen old concrete with railroad rails in it for reinforcing. I've seen concrete foundations that had bricks and other rubble in them. There's just not much telling. And the person that built the original structure may have never heard of a building code.

 

[dbuzz]

Unfortunately OneSteel's publication on the history of reinforcing steels in Australia only goes back to the 1950s. I haven't seen the Smorgan publication.

You may need to take some cores and have the concrete and steel tested if you can't otherwise establish the grades.

I have a few suggestions:
- Contact the Australian Concrete Repair Association
- Contact your local University's civil engineering department
- Perhaps a 'left-field' suggestion -- Contact your local division of Engineers Australia. They have a retired engineers group, which I'm sure would love a receive a query like this, and they're probably more likely to have an idea than current practitioners.

 

[DMcGrath]

Don't forget you might also use X-ray to see the spacing and orientation of the reinforcing. Sure beats blindly coring a bunch of holes.

 

[archeng59]

If you do not have good data, have core samples made of the concrete to obtain cylinders for compressive strength tests. Similarly, you could have pieces of the rebar tested for strength. You likely already know this, but I mention it anyway.

I've worked on several existing buildings constructed between 1900 and 1930's in central U.S. Most of the concrete strengths varied between 1500 psi to 2500 psi for cast-in-place concrete columns, beams and elevated slabs. Those values are based on compressive strength tests made using core samples from the existing concrete. Rebar configurations varied considerably. Smooth round bars. Round bars with deformations. Square bars with and without deformations. Stranded wires. I found a one-way slab that was reinforced with what appeared to be barbed wire. Fy for the bars tested varied from approx. 20 ksi to 40 ksi. Don't know if this helps.

 

[broekie]

For bridges in Michigan built in 1929, we assume f'c = 2500 psi and a rebar fy = 33 ksi. Not sure how this translates to what might have been used in Australia, though...