shows different tensioning means loss of contrast
curves for prestressed. From the figure, twice-tensioned
prestress can reduce the later loss of the prestressed bars. The
loss for prestressed can be reduced by 5.9% after the beam is
tensioned for three days, while the loss can be reduced by 5.6%
after it’s tensioned for seven days. Contrasting to the loss ratio
for prestressed after the first tensioned, we can see that the
earlier it’s tensioned, the more loss for prestressed will be.
Therefore, using twice-tensioned method will make up for the
loss for prestressed which loses after being once tensioned
prestressed. Meanwhile, because of early development of
creep, post development of creep will be reduced and the
influence of creep on prestressed will be weakened.