Calculate the nominal flexural and shear strength of an HSS 8×4×1/8 section. ? y =50 ksi . Please use hand calculations to solve

Assuming k = 3000 lb/in2, and considering only the bending stress:What rail type would you recommend if two identical forces of P = 30,000 lb, 70" apart, are applied to it?

How much steel would be required (As) in order to make 'a' be the exact flange thickness of a T Beam with the following details: f'c = 3000 psi, fy = 40000 psi, hf = 5 inches, d = 20 inches, b = 48 inches, bw 12 inches, = 8 in^2 15.3 in^2 3.825 in^2 6.375 inches

Aluminum is a poor material to reinforce concrete with, especially as opposed to steel.  There are five primary reasons why; Cost, strength, and stiffness are the first three.  Please name the fourth and fifth reasons and then please explain in detail what would occur if these two were done.