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

When verifying the rafter, which two zones are likely to be critical for lateral-torsional buckling?

Adjacent to the haunch, in the gravity combination of actions
Around the point of contraflexure
At the maximum sagging moment, near the apex
Adjacent to the haunch, in the reversal combination of actions

What steps are effective in reducing the calculated deflections at SLS?

Modelling the stiffness of nominally pinned bases
Using higher strength steels
Using members with a higher inertia
Adding restraints

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%

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

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

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

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

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

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