Portal frames quiz

Please answer the following 10 multiple choice questions, then click 'submit' to check the result. The pass mark for a CPD certificate is 8 out of 10, and you may retake the quiz as many times as you wish, but the questions will vary! Please note that one, two, three or all of the possible answers presented for each question may be right, and to gain a mark for that question all correct answers must be identified.

Good luck

Portal frames

When might the inside of a gable column be in compression?

When the gable is the leeward face of the building
When the wind direction is parallel to the gable
When there is a large internal pressure
When the gable is on the windward face of the building

What does an 'unrestrained' column imply?

No intermediate restraints to the inside flange can be provided
There is no stiffener at the connection
There are no side rails
The bracing is attached in a different bay

Which of the following situations should be verified as an accidental combination of actions?

Snow removed from one roof slope
Snow accumulating behind a parapet
Snow on the roof if the altitude is above 150 m
Snow accumulating in a valley

If a member is not adequate when checking lateral-torsional buckling, what steps are effective in increasing the resistance?

Provide additional restraints
Reduce the spacing of the restraints
Select a larger and heavier member
Use higher grade steel

When should a portal frame be used for the gable frame?

When future extension is anticipated
For aesthetic reasons
To save weight
So that gable columns are not required

When might a Morris stiffener be required in a haunch connection?

When the vertical shear exceeds the resistance of the rafter web
When the panel shear exceeds the resistance of the column web
Whenever a compression stiffener is provided
To provide a fixing point for the vertical bracing and the eaves member

Which of the following combinations of actions should be verified for portal frames?

Permanent + Wind
Permanent + Snow
Permanent + Snow + Wind
Permanent + Wind + Imposed

How long should the haunch be?

To the third purlin
Until the hogging bending moment is approximately the same as the sagging moment
Three times as long as its depth
One third of the column height

The adjustments to αcr in the calculation of αcr,est allow for what phenomena?

The high moment and shear combined
The flexibility of the structure
The axial load in the columns and rafters
The base fixity

How can second-order effects in portal frames be allowed for?

By using a second-order analysis
By amplifying the lateral loads
By using S355 steel
By down-rating member resistance by 10%