^ppfdkjbkq=T=plirqflk=hbv=Erpb=lc=bu`bi=pebbq=clo=ob`q^kdri^o=`lirjk=abpfdkF

Select a cross section for a square tiedcolumn to support axial loads PD=400kip,PL=485kip, MD=50k', ML=48k'. Try touse about 4% reinforcement with f'c=4ksiand fy=75ksi. Select ties and sketch thecross section with ties.

fy 75ksi:= f'c 4.ksi:= ρg .04:= ϕ .65:=

PDL 400kip:= PLL 485kip:=

Pu 1.6PLL 1.2PDL+:= Pu 1256 kip=

MDL 50k':= MLL 48k':=

Mu 1.6MLL 1.2MDL+:= Mu 136.8 k'=

Processing Data:

eccMuPu

:= ecc 1.31 in=

ΦPn_max Pu:=

ΦPn_max 0.8 ϕ⋅ .85 f'c⋅ Ag⋅ ρg Ag⋅ fy .85 f'c⋅−( )⋅+ ⋅= solve Ag, 385.59779939090283918 in2.0⋅→ ACI 318 10.3.5.2

OR

Ag 25.ΦPn_max

ϕ 17. f'c⋅ 20. ρg⋅ fy⋅ 17. ρg⋅ f'c⋅−+( )⋅⋅

:= Ag 385.6 in2=

Solving for square column edge dimension:

edge Ag:= edge 19.6366 in= Override edge 20in:=

Ag edge2:= Ag 400 in2=

ΦPn_max 0.8 ϕ⋅ .85 f'c⋅ Ag Ast−( )⋅ Ast fy⋅+ ⋅= solve Ast, 14.740008594757198109 in2.0⋅→Ast 14.74in2:=

ρAstAg

:=ρ 0.037=

Use 4#11 rebars on corners, and 4 #14 rebars on midpoints - see results below