READ PROPERLY FIRST: Note: evaluate the allowable stresses given by the code using uncracked sections. A rectangular pre

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READ PROPERLY FIRST:
Note: evaluate the allowable stresses given by the code using uncracked sections.
A rectangular pre-tensioned prestressed beam has a width of 300mm, a total depth of 600 mm, and a simply supported span of 16m. Grade 1725 stress relieved prestressing tendons are placed at a constant eccentricity ot 130mmm. The total area of the tendons, subjected to an effective prestressing force of 637.5 KN. is equal to 650.3 sq.mm. Use Eps 186 MPa. fc'= 35 MPa and R 0.25 It is expected that at the time of transfer, the concrete must have reached 75% of its specified strength Assume that the maximum moment during service loads is 720 KN-m (due to sustained loads).
Calculate the concrete the code using an uncracked sections. stresses at the critical sections during the initial stage.
choices:
a) 4.25 MPa & 32.22 MPa
b)6.72 MPa & 26.74MPa
c) 3.12 MPa & 31.97MPa
d)5.37 MPa & 28.66 MPa