Bevel Weld on Bar Post
Bevel Weld on Bar Post
(OP)
I need to design an eccentric welded connection for a steel rectangular bar rail post. This is for a rail on a stair stringer.
The bar post is being welded directly to a stringer channel flange. The bar post is 1/2" x 1-1/4" and the width of the channel flange is 1-1/2". Thus, based on these dimensions, I do not have the room to develop the moment required at the base by using fillet welds (i.e. the thickest weld I can get on the short sides of the post is (1.5-1.25)/2 = .125" welds, which is not adequate).
So, I have determined that I am going to need to use a bevel weld in which a portion of the base of the bar post will be beveled in order to make room for the weld. I am just unsure of how I determine how much needs to be beveled off. Do I treat it like a fillet weld and bevel off the width required to make the design work as a fillet weld??
I hope this question clear, I can draw a sketch if necessary.
The bar post is being welded directly to a stringer channel flange. The bar post is 1/2" x 1-1/4" and the width of the channel flange is 1-1/2". Thus, based on these dimensions, I do not have the room to develop the moment required at the base by using fillet welds (i.e. the thickest weld I can get on the short sides of the post is (1.5-1.25)/2 = .125" welds, which is not adequate).
So, I have determined that I am going to need to use a bevel weld in which a portion of the base of the bar post will be beveled in order to make room for the weld. I am just unsure of how I determine how much needs to be beveled off. Do I treat it like a fillet weld and bevel off the width required to make the design work as a fillet weld??
I hope this question clear, I can draw a sketch if necessary.






RE: Bevel Weld on Bar Post
RE: Bevel Weld on Bar Post
I would really have to pile up the weld on the sides , since the weld on the side so much less efficient than the welds on the top ((I forget the exact requirement right now - not at the office). I would like to know what my options are with the bevel weld. Either way, I may need to use it at some point in the future.
RE: Bevel Weld on Bar Post
RE: Bevel Weld on Bar Post
RE: Bevel Weld on Bar Post
You're required to oppose a 200 lb horizontal force sideways at the top of the 36" (or 42") high handrail/guardrail. Your fillet welds up the side of the channel will be strong enough - unless you are trying to just use the "top" of the channel?
How are you opposing the "rotation" force on the channel? What size channel? What size stringer, post, picket are you thinking of? How far between posts? How are you anchoring the posts? Commercial or residential construction?
RE: Bevel Weld on Bar Post
Some of the posts here are right about the stringer flange. That might not calc out for bending and might need to be stiffened with a gusset plate underneath. The 200 lbs. requirement at the top of the hand rail/ guard rail, that doesn't need to be resisted by a single rail post though. Assuming all the rail posts are connected at the top with a continuous piece of steel that acts as your hand rail/ guard rail and they are not spaced too wide apart.
RE: Bevel Weld on Bar Post
If so, your numbers are not good. Your bending stress is somewhere around 55ksi. Understanding that many codes still allow a 1.33 overstress for handrails and stair sections, you are still using a lot of the capacity for any level of comfort, assuming you are using 50ksi yield strength material. If you are using 36 or 33 ksi material, you're sunk.
Your other option, assuming you can get the stress levels to work out, would be to provide a gusset on the back (stair) side of the bar, to increase the weld area and to reinforce the probable overstress condition.
A sketch would be helpful (as racookpe1978 noted) to see if we are making correct assumptions.
RE: Bevel Weld on Bar Post
Your assumptions are exactly correct as you have described it. You are also correct in that the 1/2" x 1-1/4" flat is inaquate by itself as a bending member. The architect is going to have to reduce the spacing enough to allow contribution from more that one post (we are still ironing out the details).
I realize that I have a lot of options with the welding.
As some of you have pointed out, bending in the channel web may be a concern. It is a MC12x10.6
RE: Bevel Weld on Bar Post
The channel web is probably not a significant concern. The tread supports (assuming typical configuration) will stiffen the web a fair amount. A slightly smaller stringer section is common in this area (MC10x8.4).
RE: Bevel Weld on Bar Post