Stainless Steel Bolts in Wood Truss

[tclat]

Hi,

I have a wood truss in a building near the ocean and would like to specify a bolt with good corrosion resistance.

I have looked through my timber manual which states that bolts meeting the requirements of ASTM A307 would be satifactory.

I am looking at stainless steel bolts to ASTM f593 and ASTM A193. While it is easy to satisfy the minimum tensile strengths, I can's satisfy the hardness requirements. Only ASTM A193 B8M Class 2 satisfies the elongation requirements but I understand this bolt is mainly used in high temp applications.

If my bolts are in shear, should I be concerned that I am not satifying these requirements? Is there anything else I need to stasify?

I am also using stainless steel plates.

My initital thoughts are that the wood would fail before the bolts in any circumstance so it shouldn't be a big deal. Any other comments would be useful

Thanks

 

[MiketheEngineer]

You are probably correct

 

[Ron]

Use F593 bolts....316 or 304 will give better corrosion resistance than A307 bolts. The elongation is not necessarily a significant parameter for bolts that are primarily loaded in shear. The elongation parameter is, to some degree, a measure of the ductility of the bolt. Good parameter for direct tension, but means less for shear.

 

[Motorspirit]

For structural purposes in salt spray environments we use A4-70 or A4-80(these are Rolls Royce) s/s bolts (tensile strengths of 700 and 800 MPa respectively . These are ISO grades but essentially are 316 cold worked bolts that have reliable strength properties

Hope this helps

 

[InDepth]

Why not specify bolts with a galvanized coating (mechanically tumbled). Also, how far are you taking the corrosion protection? Are there steel plates in your connection? Be careful with connecting dissimilar metals. But mainly, try and keep the water out!