PSAD Refresher 137: Prestressed Concrete Tub Girder with Multiple Tendons

Enrol to our Review Center: https://www.facebook.com/share/1AC24W... SITUATION: Each tendon in the simply supported tub girder shown is spaced at 38.75 mm vertically on center. Girder properties: Span, L = 31 m Cross-sectional area, A = 488.82 x 103 mm2 Moment of inertia, I = 5.82 x 1010 mm4 Total depth, H = 1.61 m yb = 524.5 mm Loads: Prestressing force in each tendon = 280 kN Loss of prestress at transfer = 15% Loss of prestress at service loads = 30% Superimposed dead load = 15.2 kN/m Live load = 13 kN/m Unit weight of concrete = 23.5 kN/m3 The bottom row of tendons is located 38.75 mm from the bottom fiber. 1. Calculate the stress (MPa) at the bottom fiber at midspan after transfer. A. 17.9 C. 71.6 B. 32.5 D. 2.02 2. Determine the eccentricity (mm) of the resultant prestressing force at midspan if the stress at the bottom fiber is zero due to the loads. A. 487.5 C. 543.7 B. 674.9 D. 557.6 3. Calculate the initial prestressing force (kN) require in each tendon to eliminate the stress at the top fiber due to the loads at the midspan. A. 775.2 C. 646.5 B. 609.1 D. 492.8 Thanks for watching! Comment for questions and suggestions for future lecture in this series. Subscribe and hit the bell button to be notified for future posts. #civilengineering #boardexam #engineering #structuralanalysis #structuralengineering #CivilEngineeringLicensureExamination #PRC #PSAD #theoryofstructures #cele #strengthofmaterials #mechanicsofmaterials #staticsofrigidbodies #steeldesign #compressionmember #trusses #friction #refresher #PSADRefresher #SHET