Self-Tapping Screw Connections
Self-Tapping Screw Connections
(OP)
When using a self-tapping screw for a connector, we are basically relying on the integrity of one thread, at least when connecting light gauge materials. If the installer doesn't have the clutch set correctly on his screw gun, he can easily strip the threads on the screw or the part being fastened (the screw is harder than the materials being fastened).
Does anyone know of information on this, any test data that could give some idea how much residual strength might be left in the connection if the threads are stripped?
I am looking at a situation where I know the tested, average pullout strength of the self-tapper; say 500 lbs. The connection fails in a wind storm, but the wind speed is less than the rated pullout capacity of the screw. Working backwards, if the screws are spaced at 10 SF/screw, the "rated" capacity is 500/10 = 50 psf. However, the windspeed associated with this load is much higher than that reported for the storm. Any thoughts???
Does anyone know of information on this, any test data that could give some idea how much residual strength might be left in the connection if the threads are stripped?
I am looking at a situation where I know the tested, average pullout strength of the self-tapper; say 500 lbs. The connection fails in a wind storm, but the wind speed is less than the rated pullout capacity of the screw. Working backwards, if the screws are spaced at 10 SF/screw, the "rated" capacity is 500/10 = 50 psf. However, the windspeed associated with this load is much higher than that reported for the storm. Any thoughts???






RE: Self-Tapping Screw Connections
What was the material guage? The pullout will differ from 16Ga to 12Ga.
RE: Self-Tapping Screw Connections
RE: Self-Tapping Screw Connections
Anyone have information on something like this?
RE: Self-Tapping Screw Connections
I would suspect that the flexural stiffness of the clip is too thin for significant forces due to 'prying action', even though the deformed shape of the hole indicates that this has occurred.
Were there similar buildings in the area that suffered similar windstorm damage?
RE: Self-Tapping Screw Connections
What got it started? Well I think that there were most likly some screws that were torqued too high and stripped the threads, they would then have no pull out strength. I don't think it would take too many to get the roof started. I was just hoping that there might be some information out there of similar failures of standing seam roofs.
RE: Self-Tapping Screw Connections