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

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

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

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

Why are Anti-sag systems used with purlins?

To control the vertical deflection of the purlins
To control deflection down the slope, and assist the alignment of the purlins
To provide restraint to the bottom flange of the purlin in an uplift combination of actions
So that the manufacturer's warranty is not invalidated

What best describes a portal frame structure?

Frames of simple construction
3-d continuous structures
Continuous frames in-plane, braced in the longitudinal direction
Continuous frames, braced in-plane

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%

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

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 the junction of the inside face of the column and the underside of the haunch be restrained?

Only in the gravity combination of actions
Always
If there is not a side rail and compression stiffener at that level
If a side rail can be provided at that level