1) A 281744 beam spans 40 feet made composite with a 3-inch thick topping. The effective width of the topping is 7 ft. Use (26) X" diameter, Grade 270, low relaxation strands at an eccentricity of 12.5 inches. The composite IT beam also includes (4) #5 bars (A :) located at 2 inches below the top fiber of the topping. The 28-day concrete strength for the IT beam is 6000 psi and for the topping is 4000 psi. Use the total prestress losses of 30 ksi. See the beam section below. Use ACI 318.

a) Use strain compatibility to determine nominal and factored flexural strength. Strain in tensile rebar must be compared to the strain limit before using a resistance factor.

b) Does the section satisfy the minimum flexural reinforcement according to ACI Section 9.6.2.1 and PCI Design Handbook Section 5.2.1.5? Show calculation.

Mathcad or MS Excel may be used to do Problem 1a). When MS Excel is used, write down formulae and calculation steps, i.e. strain calculation, the force equilibrium using materials' stress-strain behavior, and the flexural capacity using the final "c" from the iterations to match the cells that contain results.