calculating joint slippage

[calculor1]

Does anybody know of any references for calculating the deflection of timber truss split ring connections.

 

[JAE]

I would think that split ring connectors in wood would have very little, if any, slippage. They are basically ring "teeth" that grip the wood quite securely.
Do you know if there is truly slip in these things?

 

[calculor1]

Here's my situation, I have a truss where the member deformation is 36mm based on my model. The measured deflection varies from truss to truss, 100mm to 150mm. I know the truss was fabricated using unseasoned lumber. The NDS for wood construction recommends increasing the DL deflection by a factor of 2. Therefore my calculated deflection is 72mm. Based on several papers I have read the only other explanation for the remainder of the deflection is joint slippage. On the other hand I also have read a paper which recommends that the joints be modelled as semi rigid joints based on testing. So at this point I would like to determine the contibution of the joint slippage and compare to my field memasurements.

 

[SlideRuleEra]

See Table 21.5 at this link:

http://books.google.com/books?id=Ye...ts=XTH3_DBL3x&sig=U8VYQLc0TPNIU4MIew5rCg0HkhQ

http://www.SlideRuleEra.net

 

[calculor1]

Thanks, exactly what I need.

 

[JAE]

Way to go Slide...

Are those values in meters? It's pretty small. If so, then the split rings don't move much...

 

[calculor1]

The actual slippage per joint is not much, however on the big picture the joint slippage is probably around 50% or more of the truss deflection. In fact one of the papers I have read the actual joint slippage is around 7 times the member deflection!!!

 

[SlideRuleEra]

Thanks, JAE. I have a 1940's document on my website titled "Fabricating TECO Timber Connector Structures" that has some information on split ring connectors, but slippage is not discussed. The document is on this page:

http://www.slideruleera.net/miscellaneous.html

http://www.SlideRuleEra.net