Slip Critical Bolts for Long Slotted Holes
Slip Critical Bolts for Long Slotted Holes
(OP)
I've read a number of papers which seem to imply that, whenever long slotted holes are used for single plate shear tab connections, the bolts must be slip critical. The attached paper mentions it at the top of page 10.
Why do long slotted holes necessitate slip critical bolting?
Thanks,
KK
Why do long slotted holes necessitate slip critical bolting?
Thanks,
KK






RE: Slip Critical Bolts for Long Slotted Holes
See Section 4.3 (3) of the RCSC (2004) specifications. It states that Slip critical connections are required for slotted holes, except when the direction of loading is approximately normal (80 to 100 degrees) with the loading perpendicular to the direction of the slot.
RE: Slip Critical Bolts for Long Slotted Holes
AISC Section J3.8 states that connections with slots transverse to the direction of the load shall be designed for slip as a serviceability limit state.
See also commentary for this section on Page 16.1-348 (AISC)
I am going to venture a guess. If the beam deflects under loads and goes into bearing because slip is not prevented, then it may induce some axial forces? Obviously, that would be a large deflection condition.
I am sure old timers here might be able to shed more light into the requirement.
RE: Slip Critical Bolts for Long Slotted Holes
Research was done at the University of Oklahoma, by Ben Wallace, concerning the use of snug-tight connections with slots in single plates.
However, this was only applied to short-slots for the current design examples.
http://www.FerrellEngineering.com
RE: Slip Critical Bolts for Long Slotted Holes
Now, this is not to say that bolts in LSL holes for shear tabs can be bearing.
RE: Slip Critical Bolts for Long Slotted Holes
@Connect: why would one want to resist the horizontal bolt component? In a simple shear connection, wouldn't the horizontal movement help to permit the desired end rotation of simply supported beams?
Curiously, it seems that you can use LSL with the AISC extended end plate connection now (no SC required).
RE: Slip Critical Bolts for Long Slotted Holes
If standard holes or short-slots are used the rules for "standard" shear plates would apply.
http://www.FerrellEngineering.com
RE: Slip Critical Bolts for Long Slotted Holes
RE: Slip Critical Bolts for Long Slotted Holes
Sometimes people use LSL holes to accomodate thermal movement. Would that same friction and plowing have to be overcome before any joint slip would occur?
RE: Slip Critical Bolts for Long Slotted Holes
I don't like using all caps, but...
DO NOT USE LONG SLOT SHEAR CONNECTIONS FOR EXPANSION JOINTS IN HEAVILY LOADED STRUCTURES
http:
I have reviewed the expert reports of the connection which resulted in the collapse at the David Lawrence Convention Center. The connections were long-slotted single plate and knife angles connections, of large girders. In the cold Pittsburg winter the contraction of the member was restricted by the bolt plowing and friction. The connection welds were torn from the supporting member. An expensive retrofit was required. The expansion connections were replaced with slide-bearing stiffened seat connections. And the bolts were removed from the web connections.
http://www.FerrellEngineering.com
RE: Slip Critical Bolts for Long Slotted Holes
In my opinion, very few of the slip connections proposed by structural engineers are actually capable of doing any serious slipping. Particularly if they get rusty.
RE: Slip Critical Bolts for Long Slotted Holes
http://www.FerrellEngineering.com
RE: Slip Critical Bolts for Long Slotted Holes
I only live an hr or so from the center and I remember obtaining some details of the connections in a local newspaper or somewhere but have since lost them. Do you have any of those sketches?
RE: Slip Critical Bolts for Long Slotted Holes
RE: Slip Critical Bolts for Long Slotted Holes