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

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

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

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

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

What is the primary function of an eaves haunch?

To facilitate a bolted connection
To increase the shear resistance at the support
To increase the bending resistance of the rafter section
To reduce deflections

What value of base stiffness is recommended when modelling nominally pinned bases?

Zero - it's a pinned base
Zero - at ULS
10% of the column stiffness when calculating frame stability
20% of the column stiffness when considering SLS

How is a moment-resisting base commonly detailed for the fire condition, if necessary?

With a thicker base plate
With more holding down bolts
Set into a pocket cast in the base
Provided with stiffeners

How should purlins be located?

At spaces less than the maximum spaces specified by the cladding manufacturer
Spaced equally between the eaves and the apex
Judiciously, to suit the restraint to the rafter
At 1.75m centres

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%

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

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