Concentrated Load into Fully supported Wbeam in Weak Axis
Concentrated Load into Fully supported Wbeam in Weak Axis
(OP)
I have a W12 laying horizontal supported under each flange by a W8. A concentrated load from a W8 is applied to the middle of the web.
I don't believe this is a matter of using the weak axis "I" because it is supported under the flanges the entire length.
Also supposing the web is beam fully constrained at each end seems an oversimplification.
This is an existing design that I need to confirm will handle new loadings.
I have attached a sketch.
Any thoughts?
Thanks in advance for the help.
I don't believe this is a matter of using the weak axis "I" because it is supported under the flanges the entire length.
Also supposing the web is beam fully constrained at each end seems an oversimplification.
This is an existing design that I need to confirm will handle new loadings.
I have attached a sketch.
Any thoughts?
Thanks in advance for the help.






RE: Concentrated Load into Fully supported Wbeam in Weak Axis
How much load can the web handle in this configuration.
Thanks
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
If they are positively connected, check shear flow to see if you have a composite section, then do a composite section analysis to get I, Stop, and Sbtm. If it's not composite, then you would simply sum the (W12 Iy) + 2*(W8 Ix) and that will give you the total I. From that you can proportion out how much each beam is taking and do the necessary checks.
I would also check the web of the W12 for that concentrated load, you're likely to get some localized deformation there.
Maybe you can address that problem by providing stiffeners unter the column flanges between the web of the W12 and the top flange of the W8's, and another (full depth) stiffener on each of the W8's.
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
If you can spare the time, you could also check it out using a yield line analysis. That should yield a more realistic capacity.
If it were me, and it were physically possible, I'd weld a pair of stiffeners across the upper half of the W12. I'd then weld the flanges of the W8 post thingy to those same stiffeners. That way, your load flows from the flanges of the W8 post directly into the flanges of the flat W12 beam. Then it's a no brainer and you can sleep easy. The original designer probably should have done that anyhow.
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
Can you reinforce the web with a short angle or channel each side of the W8 column? If you are adding more load to the column, that is probably the best approach.
BA
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
It's the localized stress on the web that has me scratching my head.
Is it a plate fully fixed at both ends?
It is not localized web buckling, so what is it?
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
Adding the stiffeners has been considered and I will probably just do it, there will be a minimal steel cost.
I was just curious in how to go about the calc.
Thanks
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
I guess the problem is that we were all posting at the same time.
BA
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
You could, but it sounded more like he was interested in this from a theoretical perspective. On that front, I was just suggesting that pin-pin isn't what's really there.
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
RE: Concentrated Load into Fully supported Wbeam in Weak Axis
To consider a hinge along each flange would yield an ultra conservative solution which would be safe but not a good estimate of failure load.
BA