Elongation for short self stressing bed
Elongation for short self stressing bed
(OP)
I am using formulas for elongation and evrithing is OK for long bad (400ft), but for short bad (50) I am getting the forces above the 80% of the specified minimum ultimeate tensile strength.
Any idea what is wrong.
Thanks
Any idea what is wrong.
Thanks






RE: Elongation for short self stressing bed
RE: Elongation for short self stressing bed
I hope the attached file will help to understand what I am tolking about.
Thanks
RE: Elongation for short self stressing bed
RE: Elongation for short self stressing bed
You have added about 2.5% extra force, so if your initial force was within 2.5% of 80% then obviously it will be over. Is there a problem with this. After the force losses the final force will be what you started with which is less than 80%.
I do not understand why you are allowing for bed shortening. It happens as the stressing is done doesn't it, so you do not have to overstress to make up for it, same as the dead end slippage.
RE: Elongation for short self stressing bed
A good strategy to deal with this is to have long stressing beds. Large precasters have beds that are 200 feet long. Even if you are only producing product that is 20 feet long, you can put three pieces in one 60 feet long bed and distribute the slippage losses over the three peices instead of one.