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 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

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

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 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

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

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

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

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

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

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

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