Given:

Pi$=1250$ kN ; fpi$=1270$ MPa ; fpy$=1500$ MPa

$n=7($ES$)$ ; $n=6(CR)$;Eps$=186,200$MPa

concrete weight $=23\mathrm{.}54k\frac{N}{m^3},$ normal weight

Required: Compute loss of prestress due

to

Elastic Shortening$($ES$)$

a$.$ Pretensioned, b$.$ Post$-$tensioned

Steel Relaxation$($Assume $20\%$

reduction to fpi due to initial relaxation

loss, elastic shortening, and creep and

shrinkage$)$

a$.$ Stress$-$relieved, b$.$ Low$-$relaxation

use $t=3$ years.

Creep, use $W_{SD}=5k\frac{N}{m}$

a$.$ Pretensioned, b$.$ Post$-$tensioned