Columns Flashcards
What is axial loading or concentric loading?
If a load is applied through the centroid of a tension or compression member’s cross section.
What is eccentric loading?
When the load is not applied through the centroid.
What is the eccentricity?
The distance from the neutral axis to the applied to force.
What does an axial member loaded eccentrically experience?
It bends and will experience bending stress in the same manner as a beam.
Why is an axial member loaded eccentrically known as a beam column?
The member experiences both axial stress and bending stress.
In what orientation can a member be a beam column?
In either the vertical or horizontal direction.
In what direction are the axial and bending stresses oriented in a beam column?
Both the axial and bending stresses are normal stresses oriented in the same direction.
Can the axial and bending stresses be added in a beam column?
Yes
Can a column, loaded with an eccentric compressive load experience tension?
Yes
When will the tension exist in a column, loaded with an eccentric compressive load?
When the bending stress is larger than the axial stress.
Why is tension important to monitor in columns?
Columns are usually made out of concrete or materials that do not support tension stresses well.
What would cause the column, loaded with an eccentric compressive load to not experience tension?
If the eccentricity is low enough.
What is the core, or kern or kernel?
The area formed from the middle third of the centroidal axis.
Why is the core, or kern or kernel important?
If a compressive load is kept within this area the column will not experience enough tension for it to fail.
How do short columns usually fail?
By crushing.
How do long columns usually fail?
Will buckle in the transverse direction that has the smallest radius of gyration.
How do medium columns usually fail?
A combination of crushing and buckling.
What is the critical load or Euler load?
The maximum theoretical load that an initially straight column can support without transverse buckling.
What is the unbraced length, when a column is not braced along its entire length?
The unbraced length is equal to the length of the column.
What is the effective length factor when the column has pinned or frictionless ends?
1
What is a braced column?
A column that is braced against buckling at some point between its two ends.
What is the braced column length in a braced column and is it equal to the entire column length?
It will be the longest unbraced column length which will be less than the entire column length.
What is effective length?
The distance between inflection points in a column.
When is the effective length used?
When a column is fixed at its top and base
What is the range of the effective length factor K?
0.5 to 2.
What axis is used for the moment of inertia of a column?
The x axis
What is the critical column stress?
The stress given by the Euler or critical load.
Can the critical stress exceed the yield strength?
No it cannot.
What is the effective slenderness ratio?
The ratio of the effective length to the radius.
Do long columns have high or low effectiveness ratio’s?
High.
What is the smallest critical ratio that can be used fro the critical column stress?
The critical slenderness ratio.
How can the critical slenderness ratio be calculated?
From the material’s yield strength and modulus of elasticity.
What is the typical slenderness ratio range?
80 to 120.
What is the proportional relationship between the critical slenderness ratio and the compressive yield strength?
The slenderness ratio decreases as the compressive yield strength increases.
How many slenderness ratios do noncircular columns have?
2.
Why do noncircular columns have two slenderness ratios?
Noncircular columns have two radius of gyrations. One in the x axis and another in the y axis.
In the case of two radius of gyrations what will be the effective slenderness ratio?
The smallest radius of gyration will govern the design.
