Beam in Bending

[PowerRanger]

Hi Fellows

I am designing a beam web side plate connect to support a 310UB rafter 2 degree pitch (say 50kn up or down)at mid span. The clear span is 12.1m. I try to use 410UB as the beam size. Fail in member bending if design as no flange restraint.

Now if I weld the web side plate full length to the web and the flange (like a stiffener). And the 310UB is coped and connect close to the top flange. And weld a plate at the bottom of the 310UB, then bold a EA (like a fly bracing) to the web side plate near Beam bottom flange.

Will your guys say it would be the top and bottom flange restraint? Is it practical? any better idea?

Your comment will help much.

 

[apsix]

I'm not sure what you're trying to achieve but it sounds like you want the cross section at the ends to be fully restrained against twist, instead of the partial restraint provided by a web cleat. This will lead to a small reduction in the twist restraint factor kt.
I would say this is not an effective way to reduce the effective length.
For gravity loads lateral restraint is not usually a problem as the compression flange is restrained by the roof diaphram via the purlins.
Under uplift flybracing is usually used from the bottom flange to purlins at appropriate centres to reduce the effective length.
Is there a reason why you can't use the above?

John

 

[PowerRanger]

Hi John

I try to provided the restraint at mid span, not at the end of the beam. My case is a rafter use web side plate connect to the mid of 12.1m span UB beam. I try to reduce the effective length of the beam by half if the web side plate connection can provide the lateral and twist restraint to the critical flange. (top and bottom flange under down or up load).
The beam is parallel to the purlin and bolt to the panel wall at both end. no other restraint to this beam anymore. I try to reduce the size of the beam.

Marco

 

[apsix]

Marco, I think I understand.
As you suggest the web side plate should be full depth and welded like a web stiffener. Use 3-M20 bolts to the 310UB and you've got a fully restrained cross section at that point. There is no need for additional restraint to the bottom flange, the web stiffener will provide that.

John

 

[PowerRanger]

Thanks John. But I still have a little bit concern aboth the web side plate connection. It will like a pin connect to a stiff member.

By the way, do you have any idea about the bolt edge distance requirement for the panel for load bearing? I need this quite urgent b/c I need to complete the project for the client this friday.

Marco

 

[apsix]

I would be happy using that detail. There is only 100mm difference in beam depths and even if the bolted joint did slip under the ultimate load, it can't slip far. However the 'flybrace' idea will work and a version is shown in 'Steel Designers Handbook' by Gorenc et al.

"I am designing some load bearing panel wall. And would like to use the angle support the UB bolt to the Panel. I would like to ask the min. distance between the first bolt centre to the edge of the panel. I read through the hand book. it just give a example and a shop drawing. But no other mention about the edge distance requirement."
**If you're using chemsets or ferrules follow manufacturer's specification. If using thru bolts it will depend on bolt size, I would tend to use as recommended for chemsets.
The bolts should always lie within the perimeter bar, therefore about 100mm is probably the practical minimum.

"Also, for my another job, my manager suggest me use tie bar to transfer the slab load into the 100mm cladding panel then to pier support. But for me, I feel that the tie bar with ferrules is not design transfer shear force. I fax the question to the product company but still no reply. what is your comment?"
**Manufacturers give shear capacities for their ferrules, should be available on Ramset, Hilti etc websites. As I said before (not knowing the application), 100mm seems thin.

 

[PowerRanger]

Thanks John. I used Chemset in my design. (Their new design guide will come out 1 month later. That is better than the current one. But this is another story.)For another job, the trouble is the builder want to use Tilt-Lift (company) product. I called there, no sale engineer. Do you have any information for this company's product.
But anyway, new problem comes on my urgent job, not sure if can sleep tonight. I think this is engineer's life. Thanks for your time.


Marco

 

[apsix]

Marco
Perhaps you haven't got internet access, but their web address is

http://www.tiltlift.com.au,

I couldn't find any capacities on their site.
For approx capacities identify similar Ramset/Hilti product and downgrade by 25% maybe?
head office phone 03 9583 0115, fax 03 9583 9293

I had never previously heard of them.

John

 

[PowerRanger]

Thanks John. May be I missed something on the web. Before I download their catlogue, but only size showed.

Thanks anyway.

Marco