Answer:
above 924.24 kips column will fail
Step-by-step explanation:
given data 
length L = 20 ft
section = W16 × 100 
steel = A992
to find out
at what load column will fail
solution
we will calculate here ρ critical
so here using table for W16 x 100 
Ixx = 1490 

Iyy = 186 

so
ρ critical = π×E×I(min) ÷ ( KL)² ..................1
here we know E = 2.9 × 
 and K = 1 for pin column
 and K = 1 for pin column
so from equation 1 
ρ critical = π×2.9 × 
 ×186 ÷ ( 20×12)²
 ×186 ÷ ( 20×12)²
ρ critical = 924.24 kips
so above 924.24 kips column will fail