The section of a Super-T prestressed concrete girder is shown below. The girder is simply supported on a span of 7.0 m and are pre-tensioned with total initial force of 825 kN from low-relaxation strands. The girder supports a total dead load of 2 kPa and live load of 6 kPa. There is a loss of prestress of 0.2 at service loads. Assume "-" for compression and "+" for tension. Hint: Assume tributary width is equal to flange width. Properties of the section: A = 100,000 mm2 INA = 940 x 106 mm4 All measurements in the drawings are in millimeters. 1. What is the stress, in MPa, at the top fibers of the girder at end span due to initial prestressing force only? 2. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to initial prestressing force only? 3. What is the stress, in MPa, at the top fibers of the girder at end span due to prestressing force and service loads? 4. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to prestressing force and service loads? 5. What is the additional load in kPa such that the stress at the bottom fibers of girder at midspan due to service loads and prestress force will be zero?
The section of a Super-T prestressed concrete girder is shown below. The girder is simply supported on a span of 7.0 m and are pre-tensioned with total initial force of 825 kN from low-relaxation strands. The girder supports a total dead load of 2 kPa and live load of 6 kPa. There is a loss of prestress of 0.2 at service loads. Assume "-" for compression and "+" for tension. Hint: Assume tributary width is equal to flange width.
Properties of the section: A = 100,000 mm2
INA = 940 x 106 mm4
All measurements in the drawings are in millimeters.
1. What is the stress, in MPa, at the top fibers of the girder at end span due to initial prestressing force only?
2. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to initial prestressing force only?
3. What is the stress, in MPa, at the top fibers of the girder at end span due to prestressing force and service loads?
4. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to prestressing force and service loads?
5. What is the additional load in kPa such that the stress at the bottom fibers of girder at midspan due to service loads and prestress force will be zero?
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