Overview
Problem 1
A W14x74 column is 25 ft long and both ends of the column are pinned.
a) Is the buckling of the column controlled by the x- or the y-axis? Explain your response.
b) What is the maximum allowable axial load the column can support?
Given:
· Cross-sectional properties:
o A= 21.8 in2
o Ix= 795 in4
o Zx= 126 in3
o rx= 6.04 in
o Iy= 134 in4
o Zy= 40.5 in3
o ry= 2.48 in
· A992, Grade 50 Steel: Fy= 50ksi and Fu= 65 ksi
· E= 29,000 ksi
Hint:
1. Refer to lecture 8 notes for K factor and flexural buckling equations.
Problem 2
A square HSS10x10x1/2 column is 20 ft long. The bottom of the column is fixed and the top is free to
translate but fixed for rotation. Determine whether the column is adequate to support the given loads.
Given:
· Cross-sectional properties:
o A= 17.2 in2
o Ix= 256 in4
o Zx= 60.7 in3
o rx= 3.86 in
· A500, Grade C Steel: Fy= 50ksi and Fu= 62 ksi
· E= 29,000 ksi
· PDL= 50 kips
· PLL= 70 kips
Problem 3
A rectangular HSS10x4x1/2 column is 20 ft long. The bottom of the column is fixed and the
top is pinned. The column is braced against the buckling in the X plane at mid-height.
Determine the compression capacity for:
a) Buckling in the X plane.
b) Buckling in the Y plane.
c) Between the X and Y planes, which one controls the compression capacity?
d) If the section was not braced at midheight, without doing any calculation, which
direction the column would buckle in (x plane or y plane)?
Given:
· Cross-sectional properties:
o A= 11.6 in2
o Ix= 129 in4
o Zx= 34.1 in3
o rx= 3.34 in
o Iy= 295 in4
o Zy= 17.6 in3
o ry= 1.59 in
· A500, Grade C Steel: Fy= 50ksi and Fu= 62 ksi
· E= 29,000 ksi
Figure 1- Elevation
Figure 2- Column section
Figure 3- Elevation
Figure 4- Column section
Figure 5- ISO View
Homework 6 Course 523bl - Fall 2022
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Problem 4
A steel column is supporting the loads listed below and is pinned at both ends and has an unbraced length of 26 ft.
Use ASD design approach.
a) Using the Allowable Compression table below, what is the lightest W14 that can support the loads?
b) If the column fixity at the bottom is changed to fully fixed, what would be the lightest W14 profile?
c) The contractor has already procured the W14x90 profile for this column. Would the column work by changing the
fixity at one or both ends? Explain your answer by calculating the new column capacity.
d) For Part c, what other approach would you recommend for making the W14x90 profile work? No calculation is
required.
Given:
· PDL= 250 kip
· PLL= 450 kip