Low-Lax vs Stress Relieved Prestressing Strands
Low-Lax vs Stress Relieved Prestressing Strands
(OP)
Does anyone have an idea when Low Relaxation Prestressing strands became available?
I have to determine the strength of some old hollow core plank that were made in 1971, but the precaster is now out of business and I would like to get an idea of what was done back then.
I know the difference between the two is pretty big in terms of losses so I definitely feel this is pretty critical.
I have to determine the strength of some old hollow core plank that were made in 1971, but the precaster is now out of business and I would like to get an idea of what was done back then.
I know the difference between the two is pretty big in terms of losses so I definitely feel this is pretty critical.






RE: Low-Lax vs Stress Relieved Prestressing Strands
RE: Low-Lax vs Stress Relieved Prestressing Strands
I first got involved in Prestressing in 1976 and Low Relaxation strand was still not available in Australia then if I remember correctly. It was introduced over the next few years but both were available for a while.
I do not know if it was earleir in USA.
RE: Low-Lax vs Stress Relieved Prestressing Strands
Pick the longest plank, cut its side connections and fill a large bag full of water at the center of the span (you will need to know the final weight - 15 psf over the middle third should give you a decent result). Monitor the deflection change and extrapolate the plank properties.
Final step - write a report for publication with lots of pictures.