Steel Columns Flashcards
In a free standing column, with no intermediate bracing, which is the critical
buckling axis: -x-x or y-y?
y-y
What is the usual k factor for simple steel construction?
1.0
About which axis would an engaged column (web perpendicular to wall) like in
the lecture hall buckle?
x-x
What is the recommended slenderness limit for steel columns?
200
What limits the upper end of stress values for Euler equation?
The crushing failure of the material
What do the two numbers used to designate a wide flange steel section
describe?
Nominal depth in inches and weight in pounds per linear foot. e.g. a W8x35 is nominally 8 IN deep and weighs 35 PLF.
If the effective length factor, K, is larger than 1.0 would you be designing a frame
with sidesway or without sidesway?
With sidesway (i.e. no cross bracing)
What factors affect the calculation of k?
Moment of Inertia and length of beams and columns at each end of the column as well and the connection itself.
What are the characteristics of an ideal column?
initially straight
homogeneous material
concentric loading
end conditions aligned
What factor has the most influence in determining the effective length of columns for buckling?
End support conditions
Along which axis does column buckling occur when the unbraced length is the
same for both axes?
The axis with the least moment of inertia, which also has the least radius of gyration
What are the different (theoretical) stiffness factors (K) for various support conditions?
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.
In a typical free standing column, what is generally the mode of failure?
Buckling
What 18th century mathematician developed the column buckling formula?
Leonhard Euler
What are the units of the slenderness ratio L/r?
Slenderness is a dimensionless ratio
What quantity does the radius of gyration describe?
It describes the distribution of the cross sectional area about its centroidal
axis
For columns with more than one slenderness ratio, which one controls buckling?
the larger
How do steel wide flange profiles designed for columns differ from beams?
The profiles are usually more square (less deep) in dimension
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
A
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.
A. Square steel tube
When is the Euler Formula valid for determining buckling?
Only below the elastic limit of the material
What is the slenderness category for a column where KL/r is greater than
4.71√𝐸/𝐹𝑦 ?
Long
Will a fixed end connection increase or decrease the effective length of a column compared to a pinned end column?
Decrease
What type of failure is more likely to happen to short columns than long columns?
Crushing, i.e. yielding of the steel
