The simply supported I-beam is to carry a uniform distributed service dead load and live load totaling0.65 kips/ft over the 50 ft span, in addition to its own weight of 384 lb/ft. The beam will be pretensioned using multiple of seven-wire Grade 270 strands steel. Eccentricity is constant and equal to 12.5 in. The prestress force immediately after transfer is 432 kips. Prestress force due to time –dependent losses is equal to 267 kips. Properties of the beam cross-section: Ac = 369 in2 Ig = 50979 in4 c1 = 20.17 in c2 = 15.83 in r2=138 in2 a) Determine the concrete stress due to initial prestressing force only. f1, f2 b) Determine the concrete stress due to prestressing force plus self-weight only after all important losses occurred. f1, f2 c) Determine the concrete stress due to prestressing force and full service load after all important losses occurred. f1, f2
The simply supported I-beam is to carry a uniform distributed service dead load and live load totaling0.65 kips/ft over the 50 ft span, in addition to its own weight of 384 lb/ft. The beam will be pretensioned using multiple of seven-wire Grade 270 strands steel. Eccentricity is constant and equal to 12.5 in. The prestress force immediately after transfer is 432 kips. Prestress force due to time –dependent losses is equal to 267 kips.
Properties of the beam cross-section:
Ac = 369 in2 Ig = 50979 in4 c1 = 20.17 in c2 = 15.83 in r2=138 in2
a) Determine the concrete stress due to initial prestressing force only. f1, f2
b) Determine the concrete stress due to prestressing force plus self-weight only after all important losses occurred. f1, f2
c) Determine the concrete stress due to prestressing force and full service load after all important losses occurred. f1, f2
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