GIRDER SPLICE - Inside Flange Splice Plate Only

[JLR6350]

I was doing some research and came across this great forum, so I'm hoping I can get some technical assistance from this knowledgeable group. I have a relative who is completely renovating a home and has asked for some assistance with some structural concerns. It's a two-story home and has a VERY unconventional flooring system. The lower level exterior walls are 8" thick concrete which support nine W12x26 girders and clear span from front to rear of the house (22'3"). The girders support four M10x7.5 beams which run the width of the house and then floor joist on top of the M10x7.5 beams. Tributary area for a girder is 171 sqft. In one of the girders a 5'9" section of it was removed for a fireplace and the cut ends of the girder are supported by the fireplace. My uncle thought the fireplace was constructed around the girder and the girder continued through the fireplace, not the case. They don't want a column to support the cut girder, because the column would be located in the center of a bedroom.

My question is in regards to splicing the girder and whether the flange splice plates can be on the inside of the flange rather than on the outside as they typically are. The reason for the splice plate on the inside is because there is a M10x7.5 beam which is located at the splice. A splice plate on the outside of the flange would require the M10x7.5 beam to be notched. I have attached a few pictures to help visualize. I haven't done any calculations yet, but would two glulams bolted to the girder be a better approach? Not sure which approach would be the most economical and constructible. Any suggestions or recommendations would be appreciated.

Thanks,
JR

 

[BAretired]

Pictures?

BA

 

[JLR6350]

Okay, hopefully this works. W12x26 is red and M10x7.5 is black.

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[IFRs]

You can't just weld in a piece of full-size I-beam?

 

[dhengr]

JLR6350:
That looks like a crazy enough floor framing system, that you would do well to have a local Structural Engineer, who can actually look at the whole building, help you with this. Three layers of standing beams, how are they interconnected and braced? How are bldg. lateral loads transmitted through this multilayer structural system? This looks like a crazy start to a DIY’er project that well likely go down hill from here.

 

[Agent666]

As IFRs said, just butt weld another section between seems like the easiest and most practical solution.

I don't see any issue with having 2 plates on the inside of the flanges as long as they are appropriately designed and there is access for welding (assuming you are welding vs bolting which doesn't look too practical with such a skinny flange).

 

[IFRs]

If you use them, web splices alone may not get you the full strength of the i-beam, needs to be checked.

 

[JLR6350]

For clarification, the M10x7.5 (black beam) I was thinking a welded splice, due to the narrow flange (2.75"), but would not be a butt weld. I was thinking of splice plates as in a bolted splice, but rather than being bolted the splice would be welded. The flange splice plates would be on the inside of the flange due to the height restrictions.

For the W12x26 (red beam) I was thinking a bolted splice, with the flange splice plates on inside of the flange for the reason mentioned above.

@IFRs, are you refering to a butt weld? The ends of the W12x26 and M10x7.5 were cut by an acetylene torch, so the ends are irregular and not true. To me this would be difficult to perform a butt weld with not having a clean cut surface.

@dhengr, the W12x26 and M10x7.5 beams are welded together where they intersect. The W12x26 are bolted to the exterior concrete walls and the floor joist have lag screws securing them to the M10x7.5 beams.

@Agent666, just for clarification, are you referring to the M10x7.5 beam? Do you think the W12x26 could be bolted or are you suggesting it have a welded splice also?

@IFRs, I was planning to have both web and flange splice plates.

Thank you for all the responses, any other thoughts/recommendations?

 

[BAretired]

The flange and web are 4.4mm and 3.3mm thick respectively, so butt welding is not going to be easy even if the ends are true.

You could add a web plate, say 8" x 3/16" each side of the beam web, lap about one foot each end and weld to the existing web, then add an angle each side top and bottom, same length as the web plate and weld to the existing flanges.


BA