Skewed Plate (Connection Design)

[JohnRwals]

Hi!

Why do you think a loose plate is skewed rather than placed at flat position?
Is there really difference between two methods?

I am looking forward to your opinions.

Thanks!

JWR

 

[r13]

To maintain the (rotational) flexibility on the upper corner, yet maintain global stability of the beam.

 

[KootK]

Provide ability to accommodate vertical shrinkage in the spandrel without fracturing the weld?

 

[HTURKAK]

The double-tee slabs have low stiffness-to-strength ratios, and will cause significant end rotations at the supports. Apparently the designer preferred skewed loose plate to maintain pinned joint . IMO, this is not good detail . The fillet weldment at double tee plank will experience bending stresses . The flexibility should be provided by loose plate stiffness.

What about the bearing pad 1/2 in.?...could be neoprene ?

 

[JohnRwals]

I got this connection detail from PCI Journal.
This detail was used for the health center located in Florida.
...
I guess typical elastomeric bearing pad was used.
This skewed loose plate may be related with ductility during EQ.
But, I am not sure this detail is really working.
This detail can be conceivable, but not realistic?

JWR.

 

[HTURKAK]

I explained my opinion . (Opinions may differ acc. to different people ). Apparently, the spandrel beam supporting the TT plank on elastomeric bearing pads. The bearing pads will provide some rotation with relative movement and no moment will develop. And no need to for skewed joint.

This is snap from Parking Structures:Recommended Practice for Design and Construction..

 

[JohnRwals]

My point is this detail is too unrealistic.
I wonder how this designer could quantify this detail design.
I am not sure its effect is much greater than typical flat plate position.
Don't you think this is a kind of 'abuse of engineering judgement' problem?
As a similar example of 'gray area' case, I would like to share another detail.
In this case, welding should be done out of center of the plate where studs are welded.
Designer assumed that that's how he can use flexibility of embed plate as a loose plate moves.
This is good idea but hard to implement because skilled workers are scarce in the precast production line.

 

[HTURKAK]

For me,it is hard to comment without knowing the full structural system specially diaphragm requirements (Chords and Collectors ). The thread was for the probable reason for skewed loose plate connection and my opinion is , flat plate is better...
Apparently, TT plank is supported on spandrel beam with neoprene bearing pad and we can urge that the torsional stiffness of spandrel beam and shear deformation of soft bearing pad will provide 'pin connection' for the TT plank and end moment will not develop.

Your sketch , shifting the location of anchor T plate casted in spandrel and providing prying action is not also good detail. At least you may think the use of Angle ( similar analogy with clip angle connection).

I have tried to sketch with paint brush , the possible exaggerated angular rotation of TT plank neglecting the torsional rotation of spandrel.

Does this reply answer to your question... ?, if not, and if this thread is a real question, pls share some details of the bldg to get more valuable responds.