Design a 12 wide rectangular, Class U, prestressed beam. Simply-supported, span length = 30' ...

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Design a 12" wide rectangular, Class U, prestressed beam. • Simply-supported, span length = 30' • Material Properties: o Concrete design strength: f'c = 5000 psi o Concrete strength at prestress transfer: f'ci = 4000 psi o Prestressing strands: ½" diameter, 270 ksi, low-relaxation • Loads: o Self-weight (150 lb/ft3): Assume 12" x 28" section => WD = 350 lb/ft o Superimposed dead load (sustained): WSD = 650 lb/ft o Live load (transient): WL 1250 lb/ft ⚫ Concrete stress limits: use ACI provisions (with upper limit on ft for uncracked section) ⚫Prestress at transfer: fpi = 0.70 fpu •Prestress loss: assume 20% Use the following procedure: 1. Find the minimum required section modulus, S, then determine the required section depth. 2. Find the required number of ½" diameter strands so as not to exceed the stress limits (initial and after prestress loss) for a section at mid-span. Assume straight strands with c.g.s located at 3.5" to the bottom of the section. 3. For the selected prestressing strands, check that stresses at the end section do not exceed the stress limits. Design a 12" wide rectangular, Class U, prestressed beam. • Simply-supported, span length = 30' • Material Properties: o Concrete design strength: f'c = 5000 psi o Concrete strength at prestress transfer: f'ci = 4000 psi o Prestressing strands: ½" diameter, 270 ksi, low-relaxation • Loads: o Self-weight (150 lb/ft3): Assume 12" x 28" section => WD = 350 lb/ft o Superimposed dead load (sustained): WSD = 650 lb/ft o Live load (transient): WL 1250 lb/ft ⚫ Concrete stress limits: use ACI provisions (with upper limit on ft for uncracked section) ⚫Prestress at transfer: fpi = 0.70 fpu •Prestress loss: assume 20% Use the following procedure: 1. Find the minimum required section modulus, S, then determine the required section depth. 2. Find the required number of ½" diameter strands so as not to exceed the stress limits (initial and after prestress loss) for a section at mid-span. Assume straight strands with c.g.s located at 3.5" to the bottom of the section. 3. For the selected prestressing strands, check that stresses at the end section do not exceed the stress limits.

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a civil engineering problem regarding the design of a prestressed concrete beam Here are the steps to solve this problem 1 Find the minimum required section modulus S and determine the required sectio... View the full answer