Desing code or standards

[Raikku]

Is there any desing codes (NDS, AITC) that says something about stainless steel connectors or fasteners in timber structures joints?
I am more interested about strenght (desing values) than corrosion.

 

[RARWOOD]

I would think that you would just apply the provisions of chapter 8 of the 1997 NDS, using the properties of the stainless steel bolts. Appendix I should provided you with the information you need to establish the values you need to use in the yield limit equations to calculate your cennection capacity.

I don't believe any of the wood properties would vary based on the steel properties. For more information you could check with USP Structural Connectors or Simpson Strong Tie. Both of the mentioned companies publish values for high strength steel screws. I think the screws are probably grade 5 steel with a bending yield strength over 200,000 psi.

 

[boo1]

Mark’s Standard Handbook for Mechanical Engineers lists Grade 8’s as 150 ksi fasteners meaning the tensile strength is 150,000 lbs per square inch. Typical exterior stainless steel connectors are 304 or 316 which have a yield of 42,000 to 50,000 psi. Also, the ultimate shear strength of a fastener is typically about 60% of its ultimate tension strength. So given a certain diameter (cross-sectional area) and strength rating, someone can figure out how much load that fastener can carry in both tension and shear.

Calculating the tensile capability is not as easy as shear since the thinnest portion of the bolt is at the minor diameter of the threads (bottom of the thread “V”). So you need to know the nominal minor diameter of that particular fastener. That’s where military specification MIL-S-8879C comes in. It is titled “Screw threads, controlled radius root with increased minor diameter, general specification for”. It lists that and a lot more for almost all possible fasteners.

 

[boo1]

see links at:

https://www.aitc-glulam.org/shopcart/details.asp?category=technotes&item=TN-08

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm