Cracks in Round Log Girder
Cracks in Round Log Girder
(OP)
A round log girder supporting first floor and visible from the basement is approximately 8-inches wide, 7-inches deep, and spans approximately 12 feet north-south and supports a tributary floor area of 19 feet. The girder supports residential loading of 40 psf live load and 10 psf dead load. The perpendicular 8-inch block basement wall supports the end of the girder and the block was struck by a vehicle about 10 feet away from the log girder. The round log girder is split as seen in the attached photographs. The splits appear recent (exterior wood surface of log girder is darker than interior of split). The lighter color inside the split indicates to me that the splitting could be attributed to the impact. Do you agree?... or do I have other factors to consider in regard to the split?
Thanks.
Thanks.






RE: Cracks in Round Log Girder
What do you mean when you say it supports a tributary floor area of 19 feet? Do you mean it supports a tributary width of 19 feet? If so, the beam supports a tributary area of 12x19 = 228 square feet.
BA
RE: Cracks in Round Log Girder
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And for future reference, one should not post questions like this online about a possible claim. it isn't too difficult for a lawyer to rip your findings to shreds if you posed questions online. It basically discredits your engineering opinion /judgment in court (I sometimes disagree but this is how it is)
RE: Cracks in Round Log Girder
Mike McCann
MMC Engineering
RE: Cracks in Round Log Girder
Tell the owner not to go there...
Mike McCann
MMC Engineering
RE: Cracks in Round Log Girder
I'd recommend shoring and replacing, and getting them out of the house. What a pain to deal with. Do they possibly have any basement pictures that you could use for comparison?
And can you draw a picture of where the car hit, and the relationship of the wall to the beam?
RE: Cracks in Round Log Girder
Odd crack, I haven't seen a wood beam split like this during my inspections. Let's say the wood beam splits entirely in half. It would have a reduced capacity if it wasn't laterally braced but for all intent and purposed would have the same strength.
Again its hard to say if it was structurally damaged without measuring the infield deflection and comparing to calculated deflection.
Do you have any photos of the beam from further away, like overalls?
RE: Cracks in Round Log Girder
RE: Cracks in Round Log Girder
BA
RE: Cracks in Round Log Girder
As alluded to previously by BA, the structure of the beam seems funny, with a possible veneer. Is it possible that the beam may, in actuality be two beams (or more) side by side that were not stitch-bolted together, and covered by a 2X "veneer" as it were. This could account for the splitting seen - of the veneer only, and non-structural in nature. It would be very likely for two parallel beams to move differentially longitudinally in this manner from the load described.
If this is the case, just stitch-bolt the existing beams together and replace the cracked covering, assuming they are adequate to carry the floor load as BA suggests, and possible roof load depending on the framing above.
Mike McCann
MMC Engineering
RE: Cracks in Round Log Girder
PS. From my calculation with 19 ft tributary width and 12 ft span you have about a 600 psi bending stress in the girder which is acceptable for most woods. My take is you have about a 7"x7" effective crossection of girder. I have about 20 years experience designing and working with log homes. Free advice in the internet is worth every penny you pay.
RE: Cracks in Round Log Girder
RE: Cracks in Round Log Girder
RE: Cracks in Round Log Girder
Also, what is the "sag' from end to middle to other end/
If the beam is 'roughly square" but split down the middle - WITHOUT either side of the beam drooping more than the other - then it "might" be better than if one side drooped badly, or if both are sagging. The strength of a beam against the overhead load (the floor above) is primarily in the depth of the beam, but the two sides separately are not as strong than if they were bolted together or as they were originally.
you have several ways of strengthening the beam - you will need them almost certainly.
RE: Cracks in Round Log Girder
RE: Cracks in Round Log Girder