(Solved): The column cross section shown in Fig. 1 is cast with fc = 4,000 psi and reinforced with steel of ...

The column cross section shown in Fig. 1 is cast with fc’ = 4,000 psi and reinforced with steel
of fy = 60,000 psi. The total amount of reinforcement, Ast = 11.32 in2, comprised of 2 No. 11 + 2 No. 10 at
each end of the section. The reinforcement ratio, Ast/Ag ? 0.03 or ?g = 0.03.

A) What is nearly the maximum tie spacing (in.) allowed for No. 4 ties, per ACI318. Shear does not govern.

B) Determine the maximum allowed service moments for dead and live (i.e., MD and ML) of the column, if the following axial forces are present: (PL/PD = 1.5)
PD = 152 k PL = 228 k
MD = ?? k-ft ML = ?? k-ft

C) Determine the maximum required axial force (Pu) and moment (Mu) that can be carried by the column if an eccentricity of 7-in is present.

h = 20" | sh = 15” Ast = 4 No. 11 + 4 No. 10 b = 18" + No. 4 tie Bending axis E-4-60-0.75 4.0 fo - 4 ksi |- vh el - 0.1 ty = 60 ksi 3.5 FPg0.05 y = 0.75 b ein = 0.2 FPg = 0.04 3.0 e Pg = 0.03 e/h = 0.31 2.5FPg = 0.02 e/h-0.4 ksi Pg - 0.01 $ 2.0 el = 0.5 - lg = 0 elh = 0.7 1.5 His = 0.51 re/h = 1 1.0 Comp. Cont. Limit- WA Tens. Cont. Limit- 0.5 o 0 0.2 0.4 0.6 0.8 1.2 1.4 1.6 ??, bh2 ksi