Effective Stiffness of Slender Sections in AS4100

[handoflion]

Hi all,

I was wondering if anyone was aware of any reference to the effective stiffness of a slender steel section in AS4100.

AS4100 covers element slenderness for capacity calculations, but I cannot seem to find any reference to the effective stiffness to use when calculating deflections. There is a reference in AS4600 so I assumed I would find one in AS4100?

Any help would be appreciated.

Robbie

 

[Trenno]

I would say the effects you are concerned about will be apparent once a 2nd order analysis is done - the addition of big and small delta.

That being said, a thin wall section (AS4600) is quite a different beast to hot rolled section (AS4100).

 

[handoflion]

I would've thought that the mechanism relating to a reduction of stiffness was the local buckling of the slender elements, which wouldn't show up in any kind of static analysis?

 

[KootK]

Assuming that it's similar to North American provisions, there would be no stiffness reductions for hot rolled steel. Hot rolled steel is usually designed using element proportions that preclude local buckling up to the design capacities of the members.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[handoflion]

This is true, almost all the hot-rolled sections here are compact or non-compact.

My particular example involves sizing the web thickness of a cantilevered tee-section which is being governed by deflection. The architect is after a web as small as possible and I was hoping to get some insight into everyone's thoughts on the design of this?