slip critical connections and vertical deflection.

[malikasal]

Hey Guys,

will the slip in a bolted connection (when designed as bearing type) ever contribute in increasing the vertical deflection of the element??



ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[jayrod12]

If designed as a pin, then no not from analysis. Although if there happened to be immediate dropping of the beam once loaded (if lets say it was installed with the beam pushed up as far as the hole tolerance allows) then it could have the appearance of increased deflection. when in reality is would be just a one time change in elevation (assuming no load reversal)

 

[RPMG]

There is no slip in bearing type connections because the bolt is bearing on the bolt hole. There is hard contact.

Slip-critical connections can have oversized holes because they're held by bolt tension and friction.

But increased vertical deflection has not been a reported problem for either. Avoid theorists and mathematicians.

 

[JoshPlumSE]

I think some caveats are in order.
a) The bolt holes are always lager than the bolts. Therefore, you have the potential for those bolts to move around in the hole a little. This can potentially increase deflection. Probably not by much, but it would depend on the type of connection, the type of loading, et cetera. Way worse for a cantilever with a flange plate moment connection at one end. Not so bad for a redundant joist with clip angles or shear tabs.
b) If the bolt is fully pre-tensioned this will greatly reduce any movement within the bolt hole. It may not be designed as slip critical, but it shouldn't slip almost at all under service level loads.

 

[dik]

RPMG... in these environs, both bearing and slip critical bolt holes are 1/16" inch larger than the fastener...

Dik