Steel Columns

Question 1

In a free standing column, with no intermediate bracing, which is the critical
buckling axis: -x-x or y-y?

Answer 1

y-y

Question 2

What is the usual k factor for simple steel construction?

Answer 2

1.0

Question 3

About which axis would an engaged column (web perpendicular to wall) like in
the lecture hall buckle?

Answer 3

x-x

Question 4

What is the recommended slenderness limit for steel columns?

Answer 4

200

Question 5

What limits the upper end of stress values for Euler equation?

Answer 5

The crushing failure of the material

Question 6

What do the two numbers used to designate a wide flange steel section
describe?

Answer 6

Nominal depth in inches and weight in pounds per linear foot. e.g. a W8x35 is nominally 8 IN deep and weighs 35 PLF.

Question 7

If the effective length factor, K, is larger than 1.0 would you be designing a frame
with sidesway or without sidesway?

Answer 7

With sidesway (i.e. no cross bracing)

Question 8

What factors affect the calculation of k?

Answer 8

Moment of Inertia and length of beams and columns at each end of the column as well and the connection itself.

Question 9

What are the characteristics of an ideal column?

Answer 9

initially straight
homogeneous material
concentric loading
end conditions aligned

Question 10

What factor has the most influence in determining the effective length of columns for buckling?

Answer 10

End support conditions

Question 11

Along which axis does column buckling occur when the unbraced length is the
same for both axes?

Answer 11

The axis with the least moment of inertia, which also has the least radius of gyration

Question 12

What are the different (theoretical) stiffness factors (K) for various support conditions?

Answer 12

Both ends pinned; K=1.0
One end pinned, one end fixed; K=0.7
Both ends fixed; K=0.5
One end fixed, one end free; K=2.0
Q13.

Question 13

In a typical free standing column, what is generally the mode of failure?

Answer 13

Buckling

Question 14

What 18th century mathematician developed the column buckling formula?

Answer 14

Leonhard Euler

Question 15

What are the units of the slenderness ratio L/r?

Answer 15

Slenderness is a dimensionless ratio

Question 16

What quantity does the radius of gyration describe?

Answer 16

It describes the distribution of the cross sectional area about its centroidal
axis

Question 17

For columns with more than one slenderness ratio, which one controls buckling?

Answer 17

the larger

Question 18

How do steel wide flange profiles designed for columns differ from beams?

Answer 18

The profiles are usually more square (less deep) in dimension

Question 19

Assuming the areas of the two sections shown are equal, which would make a
more efficient free standing column?

A. Square wide flange
B. Rectangular wide flange

Answer 19

A

Question 20

Based on buckling capacity, which of the following sections would make the best choice for a slender, unbraced, axially loaded column? Assume areas are equal.

Answer 20

A. Square steel tube

Question 21

When is the Euler Formula valid for determining buckling?

Answer 21

Only below the elastic limit of the material

Question 22

What is the slenderness category for a column where KL/r is greater than
4.71√𝐸/𝐹𝑦 ?

Answer 22

Long

Question 23

Will a fixed end connection increase or decrease the effective length of a column compared to a pinned end column?

Answer 23

Decrease

Question 24

What type of failure is more likely to happen to short columns than long columns?

Answer 24

Crushing, i.e. yielding of the steel