25 Nov

Rational Buckling Analyses to AS4100 or NZS3404 (Part 3)

In the last post in this series we looked at a semi-real scenario where a rational elastic buckling analysis was undertaken in which we were able to determine the axial capacity of a system of members. The exact type of system of columns is sometimes referred to as a ‘lean-on’ system, whereby the column carrying no load helps to increase the capacity of the supported column. Basically if we make the supporting column (or in other words the bracing system for the RHS) stiff enough it has the effect of producing a higher mode of buckling in the supported RHS column.

Basically something where it would be hard to guess the exact behaviour and hence capacity, becomes easy peasy. It would be hard to guess the exact effective length factor k_e (in AS4100/NZS3404 terminology) or K (in AISC360 terminology) for anything but the simplest of scenarios.

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24 Nov

Rational Buckling Analyses to AS4100 or NZS3404 (Part 2)

In part 1 of this series we briefly explored the requirements related to calculating the capacity of a column via the use of a buckling analysis. Introducing the general methodology to follow and showing agreement with the normal hand methods for a known k_e.

In this followup post we look at the power and beauty of this method in being able to assess any complicated design scenario, typically ones that don’t fit in the mold of the typical idealised restraints.

NOTE – something is wrong with the formatting in this post, on mobile devices something pushes the text off the edge of the screen in portrait mode, try reading the post in landscape mode. If anyone can help sort it or knows what is wrong please post a comment…. my CSS skills are rubbish which I suspect is the problem 🙂

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20 Nov

Rational Buckling Analyses to AS4100 or NZS3404 (Part 1)

This post was inspired by a rather epic post at Eng-Tips forum, which came out of a seemingly simple request for some help on the segment length to consider for a continuous beam design to AS4100 (the Australian Steel code). Fast forward several hundred posts of debating issues of code interpretation, debates over critical flange definitions, everyone telling each other everyone else is wrong, backtracking, changing of minds, notionally proposing re-writing code clauses to suit particular sides of the argument, etc, etc. At the the end of it all there may or may not have been any real agreement reached, not unusual once engineers get to arguing.

You know when the original poster bows out at post #11, and the thread carries on for 200+ more posts that it’s a hot potato and there’s going to be a few virtual knife fights going down before it’s all said and done.

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