Stainless steel screws, aluminum plate and wood
Stainless steel screws, aluminum plate and wood
(OP)
I have an application which requires the attachment of aluminum members in single shear, or possible double shear, to cedar timbers which are unseasoned. The attachment may be made with stainless steel screws or bolts.
Does anyone know how to calculate the allowable load values for the fasteners strength in the wood?
Does anyone know how to calculate the allowable load values for the fasteners strength in the wood?






RE: Stainless steel screws, aluminum plate and wood
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The calculations are rational and give realistic values.
See Chapter 7, page 7-10
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RE: Stainless steel screws, aluminum plate and wood
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RE: Stainless steel screws, aluminum plate and wood
I am I correct?
From my copy of the "Wood Handbook", revised in 1987, my understanding is that the method of calculating fastner values is based on the wood properties not the fastner and side plate properties?
I have never liked the "Post-1991" methods for calculating fastener values. There are too many variables in the equations, so when you arrive at a number you have no good way to judge if it is correct. When in doubt I compare my calculated "Post-1991" value with the "Pre-1991" value.
One major reason I don't like the "Post-1991" method, is that it allows you to calculated values for A325 bolts used in wood connections. I think the A325 bolts are too stiff to use in wood connections, and I have my doubts that the "Post-1991" methods are appropriate for use with A325 bolts.
What do you think?
RE: Stainless steel screws, aluminum plate and wood
www.SlideRuleEra.net
RE: Stainless steel screws, aluminum plate and wood
It is my understanding that the "Pre-1991" bolt values were based on testing that was done on small diameter bolts loaded in compressdion. The results were then extrapolated for larger diameter bolts. The "Commentary" on the 1991 NDS indicated that the methods used to develop bolt values remained unchanged fromm 1944 through the 1986 NDS.
I believe the current method is based on research and testing that was done in Europe. I believe that when the 1991 NDS was developed the European Yield Model was considered the most accurate method at that time.
Beyond what I stated above, I don't really know much about the new method. I am familair with some of the questions that were raised about the old method. One objection was that the older testing didn't accurately represent tension loading.
Also there were questions raised about the reliablity of the published design values for larger diameter bolts. In the past the use of 1 1/4" or 1 1/2" diameter bolts were not that uncommon. The company I work for in the past, before my time, had a failure on a project that used large diameter bolts. Based on some in house testing after that the company didn't feel the values published for the larger diameter bolts, was reliable.
The 1991 and later NDS, do not contain procedures to calculate bolt values or 1" diameter, leaving it up to the designer to establish those values. I should mention that AITC did conduct research on bolts larger than 1" diameter and concluded that the bolt vales were reliable. However they did indicate that because of difficulty in fabricating holes for larger diameter bolts and other factors, that the use of larger diameter bolts should be discouraged