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6.8 PROBLEMS
6.1 The column AB
shown in Fig. 6.19 is made of a C10x30 and a C10x20. The two ends of the column are hinged
with no lateral displacement in any direction. At point D, lateral
displacement is prevented in the x
direction only. The length of the column is L = 15 ft. Channels are made of A36 steel with yield stress of
36 ksi. (a) What is the maximum possible allowable axial compressive load
for this column? (b) What is the corresponding minimum distance b between the channels?
6.2 A column of length 24 ft is subjected to an
axial load of 165 kips. Column ends are hinged. The column is supported at
the midheight only in its weak direction. Using A36 (Fy = 36 ksi), select the least weight tube for the
column.
6.3 In Problem 6.2, suppose you ought to use a
section made of four L3.5x3.5x5/16 with double lacings as shown in Fig
6.20. Find the minimum dimensions a
and b of the column cross
section. Next, after rounding these minimum dimensions to the nearest inch,
design the double lacing bars. Check all the necessary requirements.
6.4 A column is hinged at one end
and fixed at the other end. It is made of 2 L5x5x½ and 2 PL5x½ as shown in Fig. 6.21. The angles and
plates are made of A36 steel with yield stress of 36 ksi. Find the maximum
axial compressive load capacity of this column assuming that angles and
plates are connected to each other properly so that none of them will
buckle individually. Use the design value for the effective length factor.
6.5 A built-up column consists of an L8x6x½ and a 0.5 in.-thick
plate welded together as shown in Fig. 6.22. Both angle and plate are made
of A36 steel with yield stress of 36 ksi. The length of the column is 15
ft. The bottom end of the column is fixed and its top end is free. Find the
maximum axial compressive load capacity of this column.
6.6 Solve Problem 6.5, using steel with yield
stress of 60 ksi.
6.7 Find the lightest column made of A36 steel (Fy = 36 ksi) with hinged
ends and a length of 10 ft to carry an axial compressive force of 250 K.
Use the following shapes:
a.
W14
b.
WT
c.
Square structural tube
d.
Pipe
e.
Angle with equal legs
6.8 Find the maximum axial compressive load
capacity of a column with a length of 20 ft and the cross section shown in
Fig. 6.23. The two ends of the column are hinged. Assume the following
types of steel
a.
A36 (Fy = 36 ksi)
b.
A441 (Fy = 50
ksi)
c.
A572 (Fy = 65
ksi)
6.9 Solve Problem 6.8,
assuming that the column is an L8x6x1
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