Relaxation of steel occur after the stressed tendon is anchored. This process leads to the reduction of tendon force over time.
The amount of
stress relaxation is dependent of the initial stress and steel properties.
As much as 50% of 1000-hour
relaxation percentage can take place within the first 24 hours. For low
relaxation steel the total relaxation can be three times larger than that for
1000-hour.
Typically, the
smaller the initial stress, the smaller the stress loss due to relaxation of
steel.
At the end of the
tendon, the initial stress after lock-off can be greater than 70% UTS, while
that along the tendon can be lower than 50% UTS if significant friction losses
present.
0 Comments