Screws Though Sheet Rock

[grundsey]

Does anyone know of any published allowable shear values for connecting 2 pieces of 18 gauge (.043") Fy=33 ksi steel with #10 or #12 screws when the metal pieces are separated by 5/8" gypsum wallboard?

 

[Eng456123]

https://hcai.ca.gov/wp-content/uploads/2020/10/OPD-0001-13.pdf

there’s a table for this condition in this document

 

[XR250]

https://hcai.ca.gov/wp-content/uploads/2020/10/OPD-0001-13.pdf

there’s a table for this condition in this document

What page? I can't imagine this situation has been tested.

 

[Eng456123]

What page? I can't imagine this situation has been tested.

Page 24 (ST1.07). Not sure if it's been tested or not but if HCAI/OSPHD is using it, I bet its capacity is well understood.

 

[XR250]

Fair enough. Thanks for the info. What does the prying condition mean?

 

[Eng456123]

The figures on the next page below Table 4 show what it means to consider prying for these types of connections.

 

[XR250]

Well for the prying condition the allowable shear is basically zero (25 lbs) . Would be better to use a sheetrock anchor!

 

[Eng456123]

Yeah, I can't imagine the equipment they hang with this type of assembly weighs very much. I bet this specific condition with unistrut occurs often enough in hospitals to where they tested the specific condition. I suspect this small shear capacity is due to the high prying force effect you would get from the small width of the compression block from the unistrut (T/C couple type analysis?). Don't think I've ever heard of a sheet rock anchor but I am also still pretty fresh.. are they tested/do they have ESR reports? just curious