shear value for staples in wood

[keyPitsimplE]

Does anyone know where one can find tables that give shear values for staples in wood? I don't find it in NDS. I have a site built truss that has been put together with 3/4" plywood gussets and 7/16" crown 16 ga. x 1.75" staples that I must evaluate.

THanks,

 

[msquared48]

Get yourself a copy of ICBO Report #2403 - Pneumatic and Mechanically Driven Building Construction Fasteners as as issued to The Industrial Stapling and Nailing Technical Association (I-SANTA)- January, 1981.

They may even have a more recent one.

Mike McCann
MMC Engineering

 

[RARWOOD]

Do a web search for ISANTA NER-272.

 

[MiketheEngineer]

IBC Section 2306 has info on use of staples in floor and roof sections. No numbers just what should be used. Might be helpful

 

[keyPitsimplE]

Thank you for your advice gentlemen. I will try to find those reports.

I had found info in ESR-1539 and also in IBC 2006 Table 2306.4.1. By comparing staple & nail values in both tables in the same plywood into DF, then looking at NDS nail values, I backed out separate values for the staples I mentioned in 19/32" plywood of 51 lb & 53 lb. I was encouraged that they were so close from 2 separate tables by 2 slightly different methods. I'm curious to see what the above mentioned reports give.

 

[MiketheEngineer]

Having been in the truss industry for years - I NEVER heard of using staples. Nails, screws - yes - but not staples. That's why we invented truss plates and tested the heck out of them

How can you be sure the staples went in correctly and just didn't "bend over" when they hit the main members.

I think I might analyze each joint and add the appropriate amount of nails or screws.

 

[keyPitsimplE]

I haven't heard of using them either, but this is a site built truss by owner. I am asked to evaluate the strength.

I pulled one of the staples out to check it. It went in fine. Staples have been used for years and they do have some shear value. This is only a 17' garage truss with 25 psf snow. I planned on adding nails to bring the strength to what I need, but am finding that there are sufficient staples in it. Whomever built it put a lot in each gusset, each side. Looks well built.

By the way, I could not get ahold of either report mentioned above. They are discontinued. Could not find an updated one. Would either of you above mind either checking my value against your table?

THanks,

 

[MiketheEngineer]

For a 17' truss - and depending on configuration - you shouldn't need much

 

[keyPitsimplE]

I have since went to the equations listed at the end of ESR-1539 for staples and found that Mode IV only gives me a nominal 23 lb per staple, both legs included. All I get is 1.15 increase for snow, so 26 lb. Hmm. These are based on theory, while I think the plywood tables are based on testing.

Table 11 in ESR-1539 (pg. 16), which was easily found online, shows that diaphragms using my staples were just barely stronger in every case than the same diaphragm using 6d sinker (0.099 in) nails. I would think it would be conservative to use the NDS value for a 6d which is 53 lb.

msquared48, do you have a value for my staples listed above from your old ICBO Report 2403 for me to compare to? I'm using 19/32" ply into DF.

 

[msquared48]

I found a value for a 16 gage staple in 5/8" ply for 1.625" staples of 360 pounds per staple (180" for 6" spacing, so double for staple value). The crown was specified as 7/16" OD in the notes. With the extra 1/8" ply depth and the extra 1/8" staple length, I think 360 would still be good, even slightly conservative.

If you can get a copy of the report, you will find the value in Table VII, Page 9 of 28 of the report. The value is listed at the very bottom line of the table.

Hope this helps.

Mike McCann
MMC Engineering

 

[keyPitsimplE]

Thank you very much, Mike.

It looks like you are deriving the staple value from a diaphragm table as well, correct?. If I understood you right, you meant that a 180 plf value corresponded with 6" o.c. edge spacing. I think by your method, that would be 90 lb per staple, right? I think that would still need to be decreased by 33% per most diaphragm tables I have seen, based on the load duration assumed by the table, getting us to 67 lb.

Are you sure about that method? When you look at say a diaphragm for 8d commons @ 6" o.c. for 15/32" ply in DF, you get 260 plf. Your method would give the 8d a 130 lb value, then decreasing by 33% to get 98 lb. NDS nominal value for 8d in same conditions is 73 lb.

I found some other older engineering that gave a 53 lb. value to the same staple. That seems most reasonable to me so far.

 

[msquared48]

You're right. 90# per staple... What was I thinking???...or not. Man it's been a rough day here... Time for a couple.

Mike McCann
MMC Engineering

 

[msquared48]

FYI, Iin looking further, onl; age 3 of the same report, Table I, the value is 52# lateral strength for a minimum of 1" penetration into the main member, 7/16" crown, and Group 1 or 2 Species. Adjust accordingly for Group 3 or 4, load duration, and 25% extra for metal side plates.

Mike McCann
MMC Engineering

 

[keyPitsimplE]

I understand. No worries. Thanks for discussing this.

 

[keyPitsimplE]

Perfect! That is the match I was looking for. THanks again.

 

[keyPitsimplE]

To complete this thread, I just spoke with an ISANTA representative by phone. He indicated that the equations from ESR-1539 that I referenced in my 18 Sep 08 16:49 reply "CALCULATE THE VALUE OF ONE STAPLE LEG ONLY". The report incorrectly states that the equations consider both legs. He said this error would be corrected in the upcoming ESR. This new ESR would NOT include a table of direct staple values like I am searching for. He said the testing had not been done yet. We'll have to either use the equations or derive from the diaphragm tables.

So the theoretical and more conservative value of the Mode IV equation would be 46 lb. The 52 lb I derived from Table 11 diaphragm loads and NDS is based on testing, and is reasonable in my opinion. Close enough.

Hopefully this run-around will help someone else in the future.