glulam beam repair

[robv73]

I'm working on a repair to a bunch of glulam beams at an exterior balcony condition. The beams are dry rotten at the support to the point where they are crushing and beyond salvaging. The beam runs into the evelope of the building, and would require a lot of work to replace. I'd planned to cut out the damaged portion, replace, and post down to a new spread footing, but discovered the building is on piles and I can't land on the existing foundation anywhere. I know this is generally tough to do, but I'm considering a glulam "moment splice" with a stacked glulam and vertical through bolts with bearing plates(see attached). Does this seem reasonable?

Thanks,
Rob V.

 

[msquared48]

Probabilistic depending on what it is supporting.

Why don't you cut off the section a foot out from the building face, install a hinge hanger (top supported off existing cut section and new hung off bottom of hanger), then install an angled brace from the end of the new beam section to a steel extension from any concrete grade beams between the piles?

Replacing the entire beam would be a real .....!

Mike McCann, PE, SE (WA)

 

[Ron]

You can create moment continuity in the beam, but it must be done carefully. I would suggest that you consider a flitch beam concept, with the flitch plate (steel or aluminum) extending well beyond the damaged area. Analyze with the lost cross section and determine what the flitch plate needs to withstand.

 

[robv73]

Mike,

I thought about in the brace idea, but my grade beams are not parallel with the glulam and it would be difficult to get it installed properly given the labor pool on site.

The reason I am leaning toward the "stacked beam" is because I only have the length of the balcony to work with and the wall above has to be repaired as well. Not sure if my diagram made it online with my post. Where you able to view it?

 

[robv73]

Ron,

I did consider using a Fitch beam, but I would only be able to get a plate on one side due to framing, plumbing, etc inside the soffit beyond the balcony.

 

[dik]

Your glulam beams in the vicinity of the brown rot aka dry-rot0 have likely lost most of their strength and I would proceed accordingly. Have you looked into using penetrating epoxies. They are often used for boat repairs subject to brown rot.

Dik

 

[Ron]

dik is correct. I have used epoxy injection to repair internal wood rot in several structures...one in "a major theme park in Central Florida" and another in a church on the east coast of Florida at a military base.

Both worked well as long as there was adequate existing cross section to receive the injection.

 

[Ingenuity]

I too have used epoxy injection for wood beam repairs, some with glass FRP as supplemental strengthening.

 

[msquared48]

The op speaks of the glulam being crushed beyond salvage.

With the need for some form of containment for any epoxy fix, I do not see epoxy working in this case.

Perhaps I am missing something here?

Mike McCann, PE, SE (WA)

 

[Triangled]

hitching a ride on this thread, I'd be very interested in references as to how to use FRP and epoxy in wood beam repair/strengthening, thx,
I'll get off here.

 

[dik]

Mike:
I've used CFS containment 'U' brackets for containing epoxy in 'crushed' areas. If there is sufficient material remaining or if the existing material can be partially removed, it is possible to use penetrating epoxies. The stuff is like 100 year old Doug Fir... can't drive a nail into it or pull one out... Using penetrating epoxies requires nearly all attachments to be pre-drilled.

Dik