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fc tepat pd tendon (bagian bawah balok ) = - {( 2421 x 10^ 3 N ) / (286 X 10^ 3 mm ^2 ) - {(2421 x 10^ 3 N x 340 mm x 340mm ) / ( 3, 39 x 10^10mm ^4 ) } + [{ 1/ 8 x 6,9 N / mm x (19.8 x 10^ 3mm ) ^2 x 340 mm } / { 3,39 x 10^ 10 mm ^ 4 }]
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fc tepat pd tendon (bagian bawah balok ) = - {( 2421 x 10^ 3 N ) / (286 X 10^ 3 mm ^2 ) - {(2421 x 10^ 3 N x 340 mm x 340mm ) / ( 3, 39 x 10^10mm ^4 ) } + [{ 1/ 8 x 6,9 N / mm x (19.8 x 10^ 3mm ) ^2 x 340 mm } / { 3,39 x 10^ 10 mm ^ 4 }] = - 8,46 N / mm^ 2 - 8,25 N / mm^ 2 + 3, 39 N / mm^ 2 = -13 ,32 N / mm ^ 2 = -13 ,32 Mpa E S = fc x n ‘ = 13,32 x 7,2 = 95,94 Mpa hampir sama ES misal 92,4 Mpa OKE Tidak ada keehilangan akibat Susut dan Rangkak pada janggka pendek sebelum tranfer (SH = 0 ; CR= 0 ) Total keehilangan prategang =TL = 77,9 + 95,94 =173, 84 Mpa fst ( 1 ) =fst (tahap 1) = 1396- 173,84 = 1222 Mpa Tahap 2 Tranfer (2 hari ) s/d 30hari Keehilangan prategang akibat Rekaksasi ( RL ) ti = 2 hari = 48 jam t = 30 hari= 720 jam fst (1) / fy = 1222 / ( 0.85 x 1862 ) = 0,772 RL = 1222 x { ( log 720 - log 48 ) / 10 } x { 0,772 - 0, 55 } Mpa RL = 32, 3 Mpa Kehilangan prategang akibat Rangkak ( CR ) CR = ( UCR ) (SCF ) (PCR ) x fc UCR = ( 95 - 20 x E c ksi )=(95 - 20 x 4,415 ) = 6,7 < 11 dipakai 11 SCF = 0,87 ; V / S = 3 , SCF = 0.87--------- Tabel 3 PCR = 0.35 ; 30 hari PCR = ( AUC ) t - ( AUC ) ti = 0.35 - 0 = 0.35 ------------Tabel 5 CR = 11 x 0,87 x 0,35 x 13,32 Mpa = 44 , 615 Mpa 45
