Strain Measurement for Prestressing Strand

[HussamAli]

Hello,

As part of a laboratory experiment to use various corrosion testing techniques on prestressed concrete prisms, I am looking for a way to measure the strain of the prestressing strand in order to guarantee a stable prestressing force (0,20,40,60 and 80% prestressing) in the variably stressed concrete samples once artificial corrosion has developed.

Unfortunately, a strain guage cannot be placed on my 0.6 inch prestressing strand to its size. Do you have any suggestions? Any tips or ideas are greatly appreciated.

Thank you,

Hussam Ali
McGill University
Montreal, Canada

 

[48232220]

Have you consideered setting up a microscope with an adjacent micrometer gauge wtihin the same view as your sample.

 

[ishvaaag]

Heh, it is not possible to look at something without affecting it, or the outcome of your experiment, in this case.

If bonded, you may deduce your strain from the initial state and what you then see of deformation in the exterior of the whole prisms.

If unbonded, a mere force calibrator (essentially a embedded spring at anchor point) suffices.

Maybe the reduction in section with elongation may be used through measure of electrical current going along the strand, but I think this is unlikely enough accurate in a bondend prism, in more of the introduction of even temporary electrical currents be worrying for a corrossion experiment.