Point load on plate with continuous edge support 1

[BenAustralia]

Brain doesn't seem to be working this morning.

Just need point in the right direction really.

Large point load on the bottom flange of a Channel. Just need to make sure it doesn't yield. Don't have any finite element packages available to use at the moment.

Where should I be looking for guidance here?

In Australia btw.

Ben

 

[BAretired]

Depends on direction of point load and boundary conditions. A sketch might help.

BA

 

[BenAustralia]

It is a PFC with a gravity point load resting on the bottom flange. The bottom flange is a track for a moveable jacking system.

PFC itself is continuously restrained against torsion, so its essentially just a point load bending the bottom flange down.

Just not with it at all today it seems.

Trying to find something good on yield line analysis, can imagine that would suit.

 

[BAretired]

Yes, I think Yield Line Analysis is the way to go. In order to fail, the web has to yield where it meets the flange because the web is always thinner than the flange.

BA

 

[BenAustralia]

Web is restrained at that height though, so it may not yield before the flange does.

Any good literature on Yield Line Analysis?

There are a few design guides from the Australian steel institute that are great, and reference it, but nothing on it really.

 

[BAretired]

Why don't you turn the channel around and hang the point loads from the shear center of the channel, thereby eliminating torsion? For a track, use a continuous angle mounted on the back of the channel.

BA

 

[Hokie93]

This issue was addressed in the Steel Interchange feature in the December 1999 issue of Modern Steel Construction magazine. The question and answer are available at

http://www.modernsteel.com.

The procedure discussed is based on yield line analysis. The case of a concentrated load on a very wide cantilever beam is also discussed in Roark's Formulas for Stress & Strain (chapter 7 in the sixth edition).

 

[BenAustralia]

Thanks for that Hokie, looks like a good resource.

Any decent one out there for Yield Line Analysis in general? Unfortunately it isn't something that is taught at University here, and I'm yet to come across the need for it in what I've been doing.

Ever learning!

 

[BAretired]

There are lots of references. I first came across the method in a textbook entitled "Reinforced Concrete Fundamentals" by Phil M. Ferguson, but there are many good sources. Here are a few:

https://www.google.ca/search?q=yiel...source=hp&gws_rd=cr&ei=CRZPUoa6IYOsjALTnIHIDA

The method used in the reference cited by Hokie93 does not take into account the fact that the web of a channel is thinner than the flange. It should therefor not be used for your case.

At the risk of repeating myself, why don't you turn the channel around and attach an angle to the back of the channel to form a track?

BA

 

[BenAustralia]

Thanks BA.

At this stage I can't change their design, merely trying to certify.

If a angle was used, the same calculation needs to be made on the point load on a 'flange', so I still need to figure that out correctly.

Its a 300PFC, with a 66kN point load. I did a quick check to see what width of flange would be required, and got around 300mm. From this I don't think it is sufficient. But will try figure this yeild line analysis out.

 

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[hokie66]

I would only use an effective length of twice the width of the channel. 45 degrees just seems as much as should be relied on.