Beam connecting to column using end pl. has Axial comp.load,here weld need to check for comp load? 1

[Nanjundaswamy]

My doubt is beam weld strength calculation for shear load is sufficient need not to check for compression load.
Is my assumption is correct?

 

[jimstructures]

What is that sketch trying to show? What is the connection between the horizontal beam and the vertical column? Is the connection a knife plate shear connection at web only or a single or double angle shear connection? We cannot know what you don't call our or explain. You have to show or prove everything you wish to claim actually works. Will there be a lateral axial load transferred through the horizontal beam into the vertical column? We won't know unless you tell us how the beams and columns are loaded and what size they are. I for one am not prepared to analyze the connection based on the information you have provided.

Jim

 

[Nanjundaswamy]

Connection Between horizontal beam and vertical column is end plate connection, Beam has a Axial Compression Load and vertical shear load.
Here we need to calculate strength of weld between beam to end plate,for that do we need to consider resultant load or for pure shear, the doubt is because, i heard
For weld calc we need to consider only Axial Tension load not compression load.
Weld strength=79.64kips,
weld length=5.5", weld size=1/4"
Resultant load=35.35kips
Do we need to compare weld strength to resultant?

 

[jimstructures]

Your endplate is like no other end plate I have ever seen. My idea of an endplate is from the top of the top flange to the bottom of the bottom flange and the full width of the horizontal beam's top and bottom flanges and welded all around the horizontal beam's shape. Your sketch clearly does NOT show this kind of endplate. If it is a pinned connection you might use a single plate welded vertically to the column flange and then lapped over the horizontal beam's web and either welded or bolted to the web of the horizontal beam.

Your sketch does not shoe the second kind of connection either.

You seems to show a very small (stubby kind of plate) connecting the web of the beam to the flange of the column. I have never seen that kind of connection either.

What is that U-shaped line shown on your sketch?

I clearly don't understand what you are trying to do.


Jim

 

[Nanjundaswamy]

We have consider this as a simple shear connection and only web is welded to end plate not all around weld
I am trying shown bolt to bolt center line distance just for sake of bolting understands.

 

[DrZoidberWoop]

Your connection should include the axial load in the beam. This includes all checks for the beam, connection elements, and column.

For an end plate w/ shear and axial loads, your required fillet weld (in American Imperial units w/ AISC Code) will be:

∅=atan(axial/shear)
Combined_Load=sqrt(shear^2+axial^2)
ψ=1.392 for LRFD 0.928 for ASD
D_req=(Combined_Load)/(2*ψ*L_weld*(1+0.5*sin(∅)^1.5)) sixteenths of an inch

Make sure that your D_req <= D_max, where:

Φ_r= 0.75 for LRFD 0.5 for ASD
D_max=min(Φ_r*0.6*Fu_endpl*t_endpl/ψ , Φ_r*0.6*Fu_beam*t_beamweb/(2ψ)) sixteenths of an inch

 

[palk7 EIT]

I think your referring to 5th connection in the pic. Though I have not seen it common in the field, but I guess it's possible to do as long as your weld check numbers work out for the design loads and they are able to resist them. With regards to tension, yeah welds are designed for pulling apart forces thats why we weld so that the two pieces don't separate out. I couldn't think of a compressive force that will distort the weld capacity again it will become like a axial tension.

 

[CANPRO]

The end plate shown by OP is a very standard simple shear connection, at least where I practice.

To answer OP's direct question - the weld needs to be designed for the compressive force unless you specify that the beam web is fit to bear on the plate. What that means is that you essentially have direct contact between the plates with minimal/no gap between the two members. If that condition is not met, then the weld must be designed to transfer the compressive load. If your axial load is equal in tension/compression then it doesn't matter as the tension case will cover you for the compression case.

You'll see this commonly on column base plates, where the load is primarily compressive - you'll often see column ends required to "mill to bear" on the base plate.

In a typical modern shop, this condition is not difficult to meet. Field modifications often require consideration of this requirement - common example is base plate needs to be removed and re-welded (due to anchor position, concrete elevation...pick your reason). In this case, it is unlikely (impossible) that the ironworks will be able to cut the base plate off and provide a finished surface on the column end that would be considered acceptable to direct transfer compressive loads to the base plate...in that case, when re-welding the base plate you may need a larger weld than what was applied in the shop.

 

[JoshPlumSE]

I was going to disagree with Dr. ZoiderWoop. And, say that axial compression in your member will transfer through your beam beam to the end plate in direct bearing and to the column web in direct bearing.

But, then I started to think about what is more rigid, the weld or the direct bearing and I wasn't sure. If the fit up is perfect, it would be direct bearing. If not, then the weld would indeed take the load. So, after I thought about that for awhile, I would say that I agree with Dr. Z that using the SRSS of shear and axial for the design of the weld is probably best. It might be a little conservative, but it's probably best. And, I've definitely seen that procedure used for shear connections before.

I'm not so rigid in my belief that I'd say you were flat out wrong for assuming direct bearing for the axial. Instead, I'd say that my engineering judgment doesn't quite agree and prefers the safer, more conservative SRSS method. If it were axial tension then 100% it would be transferred by the weld and the SRSS method would be required. However, with compression, I think a legitimate argument could be made for bearing.

 

[271828]

The AISC Specification M2.6 says "Compression joints that depend on contact bearing as part of the splice strength shall have the bearing surfaces of individual fabricated pieces prepared by milling, sawing, or other equivalent means." I don't see why this wouldn't apply to situations like your end plate.

It's typically easy to show that these welds work and I'd rather not bug the fabricator with any special requirements at such a simple and lightly loaded connection, so I would design for the resultant.

That is, unless there's an easy out somewhere that I didn't find.

 

[palk7 EIT]

Yep if there is a gap, then it needs something to hold it together, otherwise that force (irrespective of com. or tension) will try to separate it.