Hello, everyone.
This is Enta.
The other day, I was out mowing the lawn for the PTA first thing in the morning lol
Mowing the grass at school is really hard work.
There are blocks all over the place—I thought they were just weeds, but turns out they're some kind of plant lol
If you can't decide... lol
At any rate, I'm glad that 80 percent of the schoolwork was done by machines.
The rest is manual work, I guess...
But that's beside the point.
Elongation of Reinforcing Bars
When it comes to tension control for rock bolts (rebar insertion work), what is the typical amount of elongation?
Since I was asked that, I’ll answer it.
Generally speaking, rebar does not stretch, but it does stretch slightly.
I'm just giving you a rough idea! I'll put it simply.
Generally speaking, based on experience, it depends on the size of the rebar, but,
It is less than 1 mm per 10 cm.
I don't think it usually goes beyond 2 mm.
This isThese are just figures based on my own experienceThat's it.
Where will it grow?
I've written about this growth before.
The extension of this rock bolt’s rebar applies only to the head portion above the sprayed surface.
The sprayed mortar areas have been filled in.
The section from there up to the point where the corner washer, jack (center hole), and lock nut engage.
Since rock bolts are generally installed to fully embed them, there is no free length.
Therefore, the only part that is not constrained when under tension is the area indicated by the red arrow in the figure above.
If the head protrusion for the head section is 10 cm, the extension range when using a unit jack will be 10 cm or less.
If you think only this part will stretch, I think you'll find even less than 1 mm acceptable.
However, the case of a center-hole jaki when using a tension bar is a little different.
I'll save that for another time.
See you later.
