Lesson test: Buckling

1.[3p]
A pin-ended steel strut 3 m long has $I = 5 \times 10^{6}$ mm⁴ and $E = 210$ GPa. What is its Euler critical load, in kN?

CorrectNot quite: 1151

2.[3p]
Replacing S275 steel with S355 in a slender pin-ended strut does what to its buckling load?

Nothing, because the Euler load depends on $E$ and the geometry, not on the strength

Correct

Raises it in proportion to the yield strengths

The answer is: Nothing, because the Euler load depends on $E$ and the geometry, not on the strength

Raises it by about 10 per cent

The answer is: Nothing, because the Euler load depends on $E$ and the geometry, not on the strength

Lowers it, because higher grade steels are more brittle

The answer is: Nothing, because the Euler load depends on $E$ and the geometry, not on the strength

3.[2p]
What is the effective length factor for a strut fixed at one end and completely free at the other?

CorrectNot quite: 2

4.[3p]
For S275 steel with $E = 210$ GPa, at what slenderness ratio does the Euler critical stress equal the yield stress?

CorrectNot quite: 87

5.[3p]
A pin-ended column has a slenderness ratio of 120 and $E = 210$ GPa. What is its Euler critical stress, in MPa?

CorrectNot quite: 144

6.[2p]
About which axis does a strut of unequal second moments buckle?

The one with the smaller second moment of area, since that is the easier way to bend

Correct

The one with the larger second moment of area

The answer is: The one with the smaller second moment of area, since that is the easier way to bend

The axis through the point of load application

The answer is: The one with the smaller second moment of area, since that is the easier way to bend

Whichever axis the end restraints allow it to rotate about most

The answer is: The one with the smaller second moment of area, since that is the easier way to bend

7.[2p]
At the Euler critical load, the analysis determines how far the strut deflects sideways.

True

The answer is: False

False

Correct

8.[3p]
Why do real columns carry less than the lower of the Euler load and the squash load?

Select all that apply

They are never perfectly straight, and the load amplifies any initial bow

Correct

The load is never applied exactly on the centroid

Correct

Rolling and welding leave residual stresses that make part of the section yield early

Correct

Their Young's modulus falls as the load rises

The answer is: They are never perfectly straight, and the load amplifies any initial bow, The load is never applied exactly on the centroid, Rolling and welding leave residual stresses that make part of the section yield early

9.[3p]
What is lateral torsional buckling?

A deep narrow beam moving its compression flange sideways and twisting, below the moment the flexure formula allows

Correct

A column bending about its weak axis under axial load

The answer is: A deep narrow beam moving its compression flange sideways and twisting, below the moment the flexure formula allows

A thin web wrinkling into diagonal folds under shear

The answer is: A deep narrow beam moving its compression flange sideways and twisting, below the moment the flexure formula allows

Twisting of a shaft under a torque larger than its capacity

The answer is: A deep narrow beam moving its compression flange sideways and twisting, below the moment the flexure formula allows

1.[3p] A pin-ended steel strut 3 m long has I=5×106 mm⁴ and E=210 GPa. What is its Euler critical load, in kN?

2.[3p] Replacing S275 steel with S355 in a slender pin-ended strut does what to its buckling load?

3.[2p] What is the effective length factor for a strut fixed at one end and completely free at the other?

4.[3p] For S275 steel with E=210 GPa, at what slenderness ratio does the Euler critical stress equal the yield stress?

5.[3p] A pin-ended column has a slenderness ratio of 120 and E=210 GPa. What is its Euler critical stress, in MPa?

6.[2p] About which axis does a strut of unequal second moments buckle?

7.[2p] At the Euler critical load, the analysis determines how far the strut deflects sideways.

8.[3p] Why do real columns carry less than the lower of the Euler load and the squash load?

9.[3p] What is lateral torsional buckling?

1.[3p]
A pin-ended steel strut 3 m long has $I = 5 \times 10^{6}$ mm⁴ and $E = 210$ GPa. What is its Euler critical load, in kN?

2.[3p]
Replacing S275 steel with S355 in a slender pin-ended strut does what to its buckling load?

3.[2p]
What is the effective length factor for a strut fixed at one end and completely free at the other?

4.[3p]
For S275 steel with $E = 210$ GPa, at what slenderness ratio does the Euler critical stress equal the yield stress?

5.[3p]
A pin-ended column has a slenderness ratio of 120 and $E = 210$ GPa. What is its Euler critical stress, in MPa?

6.[2p]
About which axis does a strut of unequal second moments buckle?

7.[2p]
At the Euler critical load, the analysis determines how far the strut deflects sideways.

8.[3p]
Why do real columns carry less than the lower of the Euler load and the squash load?

9.[3p]
What is lateral torsional buckling?