Types of Prestress Losses

Relaxation of prestressing steel, psi 8% of Q.65for 12, 500pii(8625MV/m2) 

The elastic shortening of the concrete due to the stressing of subsequent tendons results in a strain changes is considered in determining the effective force of a typical tendon. The average value of strain loss in the tendons is 

The above assumed values for the friction factors are somewhat larger than the factors measured on full-scale friction tests on the similar projects however, the listed values are based on those used in similar containments. 

Prior to the actual tensioning operation of the containment structures, friction tests will be performed to determined the actual friction factors and stressing data will then be revised as necessary. 

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