What is the maximum uniform live load $($plf$?)$ that a normal weight $($unit

weight $=150l\frac{b}{f}{t}^3)$ prestressed concrete rectangular beam can carry $($in

addition to its self$-$weight $+$ superimposed dead load$)$ considering only the

allowable stresses at mid$-$span?

Width $=16$ Height$=48$

Span $=80,$

$f^{\text{'}}{?}^{\text{'}}=8$ksi

$f^{\text{'}}{?}^{ci}=6\mathrm{.}0$ksi

$RH=70\%$

$A_{ps}=4\mathrm{.}896i{n}^2,$fpu$=270$ksi $(Low$ Relaxation$)f_{}=202\mathrm{.}5$ksi

$E_{ps}=28,500$ksi,$e_c=14(Eccentricityatcenter)f_{pe}=0\mathrm{.}85**fpi$

$f_{py}=226\mathrm{.}8ksiquad{e}_e=0(Eccentricityat$ ends$)E_c=57000**(f_c{)}^{\frac{1}{2}}$

$E_{ci}=57000**(f^{\text{'}}{?}^{ci}{)}^{\frac{1}{2}}$

$W_{sdl}=200$ plf $($permanent superimposed dead load applied after

prestressing$)$

Critical stress is at mid$-$span

Compute all the applicable pretension losses for the beam of Problem $1$

using the PCI method. Assume low$-$relaxation tendons are used and normal

weight concrete is used.

How does the total loss compare with the assumption of problem $1?($in

Problem $1$ we assumed $R=\frac{P_e}{P_i}=\frac{f_{pe}}{f_{}}=0\mathrm{.}85)$