Practice Quiz 10
Note: A one page (one sided) crib sheet is allowed during the quiz,
along with a silent, non-programmable calculator.
Clearly show your work and answer.
A 49 ft 8 in. tall W14x109 column in a three story
frame building of A992 steel (Fy = 50 ksi) is braced in
the weak axis (y-y) at 15 ft 9 in. and 33 ft 4 in. from the
base and at the top. The top is pinned while the bottom
is pinned about the y axis and fixed about the x axis.
Because there is an atrium space, the column is not
braced in the strong axis (x-x). The cross section has
the properties:
A = 32.0 in2 E = 29 x 103 ksi
I
x = 1240 in4 r
x = 6.22 in
I
y = 447 in4 r
y = 3.73 in
a) Find the critical allowable stress.
b) If the column is to support 450 k, is it adequate for
Allowable Stress Design?
c) [some short question from the text material]
Answers:
a) Fa ≈ 21.49 ksi (by strong axis, Fa-weak ≈ 23.3 ksi)
b) OK (Pa = 688 k)
Allowable stress
with Fy= 50 ksi
16 ft-4 in.
pinned about y
fixed about x
x
x
y
y
15 ft-9 in.
bracing
17 ft 7 in.
W14x109 pinned
bracing
49 ft-8 in.
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