Calculating the capacity of a floor joist that has been bored
Calculating the capacity of a floor joist that has been bored
(OP)
I have performed numerous methods to determine the amount of load carrying capacity that is lost when you bore through a floor joist--or in this situation several bores along the center of the floor joists in a new home. My calculations show a very minimal loss in capacity, and is really negligible--however,I would like to know if I missed soemthing, so I need to know what is the best method to follow in computing this loss??
This is a case of an electrical contrator boring up to in some cases 10- 5/8" diameter holes along the center of 20-2x10 floor joists spanning 13'-6". The holes are concentrated in the first 18" from the bearing wall. To apease the building contractor and local inspection officials, I specified placing a 2x6 wall adjacent to the masonry exterior wall (homeowner is finishing the basment later)and used a 2x6 brace extending 18" out from the wall(acting as a tray) attached to each joist directly under the furthest holes to provide any necessary support--however I would like to know how much capacity was actually lost in this case??
Any help is greatly apprecaited!!
Thanks!!
This is a case of an electrical contrator boring up to in some cases 10- 5/8" diameter holes along the center of 20-2x10 floor joists spanning 13'-6". The holes are concentrated in the first 18" from the bearing wall. To apease the building contractor and local inspection officials, I specified placing a 2x6 wall adjacent to the masonry exterior wall (homeowner is finishing the basment later)and used a 2x6 brace extending 18" out from the wall(acting as a tray) attached to each joist directly under the furthest holes to provide any necessary support--however I would like to know how much capacity was actually lost in this case??
Any help is greatly apprecaited!!
Thanks!!





RE: Calculating the capacity of a floor joist that has been bored
Compare your calculated value of shear stress to the tabluated allowable value (times any applicable factors) in the NDS.
RE: Calculating the capacity of a floor joist that has been bored
htt
www.SlideRuleEra.net
RE: Calculating the capacity of a floor joist that has been bored
htt
www.SlideRuleEra.net
RE: Calculating the capacity of a floor joist that has been bored
CJSchwartz--absolutely!! You confirmed my approach, and indeed the shear was my concern--hence the reason for the 2x6 wall under the affected area (of course it is overkill).
SlideRuleEra- Thankyou for the articles--I have printed them out and I am keeping them on file for future reference. I too have discovered the apparent limited amount of information on a subject I see almost daily. It seems I'm getting a lot more calls for help on this question recently...."Following the code" isn't enough to keep contractors from drilling holes where they need to go....for me to know what the actual lossses are, or the best way to calculate the loss when contractors have to bore in an area that is borderline, or not allowed in the codes is absolutely necessary.
If anyone else has a different approach--PLEASE share it!!!
Thanks again for all the responses!!!
RE: Calculating the capacity of a floor joist that has been bored