Structural Engineering Other Technical Topics

I totally forgot to list you COEng, hope that you're still willing to have a read through my thoughts and comment. It would be greatly appreciated! Bolting a piece on to the bottom and calculating bending as a single piece assumes the bolting is adequate to prevent any relative movement at all. If this is not the case, the channel will be carrying very little of the load and the original section will carry most of it- and in that case, the channels on the sides might be better. Young, thanks for the thread - I had in fact looked at it but didnt get all the answers there. Yes, there is ofcourse vertical shear in the web at centre which is in fact tmax based on the formula. And also, horizontal shear which can be calculated. I dont see the interface mechanism with the C section however for composite action. For flitch beams, I agree. I design a lot of flitch beams.

If wood/steel plate/wood I share the load based on EI of steel/wood and check each separately. Although I do take worst case on each member based on least favourable E. Plate is made a little shorter and I design bolts to transfer load to steel in span and back to timber at bearings. Bolting channels to both sides of the center of the web would be an inefficient way to go. You wouldn't get much help for the amount of material you would be adding. I had a situation recently where I could only add to the bottom flange and had only 3 inches to do it in. I ended up specifying a thick plate sized to meet the strength and deflection requirements needed. You could try the same and see what you come up with. The shear flow calculation would be more straight forward this way. The hard part would be getting holes for bolts in the existing beam.

Since you can't weld the other hard part would be getting a single continuous piece in place, but then you'll have that issue no matter what. You can try a tube also. That will have a little more area to help with your increase section properties. If you have room you can try attaching a WT shape to the bottom flange, stem up, or a smaller wide flange. That would use the added material more efficiently but if you have any reversal in load or uplift it could complicate your buckling analysis. UcfSE - I agree- channels at centre is not very efficient way. Bottom piece could be cut off past point its needed and your suggestions are all possible options to be looked at. Theres no reversal of load or uplift so that helps. JStephen has a point about bolting in clearance holes. I guess this makes HSFG bolts necessary no matter what,

I still not sure about the connection of the channels at centre. How would you go about the calculation for this, Interesting to think about, but I'm still curious about the theory behind fastening channels to the flange, even if it is a poor (read: inefficient) way to go. There could be a situation that demands it, and I would hate to let the issue go without having it clear in my mind. Have I outlined the procedure correctly above, And please don't just point out that it's inefficient. I get it, better is possible here, but might not be possible elsewhere. I see no problem with your welding bars - doesnt apply to my case but its a solution all the same. Bolting channel to bottom flange - again I dont see why that should be a problem. I see it similar to a crane girder, for example - albeit inverted.

Slip in bolts as mentioned above maybe a factor. Unless someone else can throw some more light on bolting channels at centre and either side of web however I cant see how that works. If i was supporting some cross members for example, and bolted a channel on the web for them to seat on I would just treat it as vertical load on the web. Dont see how that would increase z of the main beam. COeng I think stated the same. Adding channels to both sides of the beam web WOULD be beneficial, however (sorry but I must say it) very inefficient. 0. Nadda. Shear flow is calculated based on the first moment of the CONNECTED part. Q for the channels about the neutral axis in this case is zero. Young is correct in saying that shear flow would be maximum at towards the middle of the wide flange -if you were trying to weld the wide flange together at that point.