Nail shear strength values

[DRP]

It is certainly good to to keep working towards understanding whats holding things up. These are some more related links that came to mind.

APA's website has their "Wood University", the tab is to the lower right on this page:

http://www.apawood.org/

There is a good section on connections

For interchanges this is worth having;

http://www.icc-es.org/reports/pdf_files/ICC-ES/ESR-1539.pdf

On the awc.org site under the free publications is a paper on general dowel equations it used to be labelled tech report TR12... a free source of the info behind the info in the NDS. The NDS commentary was a free download from their site. Also the publications page has the Supplement of wood design values for the NDS.

 

[Sifu]

Here is the way I look at basement walls. I'll list the steps as I do them. This is all from IRC 2006.

I'll use an 8" reinforced masonry wall, 8' tall with 7' of unbalanced fill and the soil load column of 45lbs.

1) table 404.1(3) limits prescriptive application to a building with an aspect ratio of 1.4, if the aspect ratio does not exceed this then I continue

2) table 404.1.1(2) prescribes the construction and reinforcement requirements as a #6 bar at 48" on center

3) table 404.1(2) prescribes an anchor bolt spacing of 12" on center for the green plate to wall

4) table 404.1(1) prescribes the green plate to joist connection of "C" 1 1/4" steel angle bolted to each joist OR an equiv. connection that provides 321.6lbs of resistance

This is the way I connect the load path of a foundation wall which is pinned at the bottom by the slab, made strong enough to resist forces and then pinned at the top by the green plate, joist connection and floor diaphragm. The reason I look at the alternative of the 321lb connection is it is sometimes more attractive to come up with that connection than it is to bolt a steel angle to each joist.

This is my understanding of the way the system works. It makes sense to me but if I have misunderstood it please show me the correct way.

By the way, from the IRC Q&A 2006:

Q-We don't understand the use of the word "or" in section R502.2. It seems to imply that the last part of the sentence is optional related to the construction of floors. Is this correct? A-Yes. The AF&PA NDS is the engineering standard............The code is a prescriptive code. It allows the use of the NDS as an alternative..............

Q-Whose option is it to use this document? A-It is up to the owner/designer/builder..........

Q-Can a building official require compliance with either the NDS or WFCM? A-No, but he or she can require engineering to substantiate an installation of elements or portions that do not conform.....In some case the builder may find it easier to use the WFCM or.....NDS

These questions seem to back up what I believe about the NDS, that it is a tool, not a code. It is used by design professionals to design and sometimes by me to understand or assist in instances like the one above. Is this not correct?

 

[Mark K]

It is appropriate to expect the applicant to know which codes were legally adopted along with any legally adopted amendments. This information should be readily available from the building department. The fact that engineers and contractors don’t check is their problem.

Conversely the limitations the building official and inspectors are forced to work under should not be the concern of the permit applicant. I do not see the building department letting me off easy when I have had a hard time. If you do not have the tools and training to do your job that should not be my problem.

While I may have my problems with some of the California building departments my sense from this forum is that in some other states the management of the building departments is sometimes much worse. This is a problem that ICC should address.

If you are limited to dealing with the first 10 chapters of the IRC what happens when somebody wants to construct a building outside the scope of the IRC or what you have adopted? Does this mean that the IBC has not been adopted? Does not the IRC assume that when you exclude the scope of the IRC that the applicant can use the provisions of the IBC?

 

[mtlogcabin]

These questions seem to back up what I believe about the NDS, that it is a tool, not a code. It is used by design professionals to design and sometimes by me to understand or assist in instances like the one above. Is this not correct?

Agree 100% it is a tool used by the designer

Suggestion

Have a local engineer take the worst case scenario for your area and provide a design. The AHJ I work for did this and now all foundation walls require more steel #4 16" OC EW and J-Bolts 32" OC with 2x2 washers. Maximum wall length is 40 ft. Does not matter if it is a crawlspace or a 9 ft basement wall with a 3 story wood frame house they are all the same. Consistancy for the contractor and easier for us.

 

[ICE]

Agree 100% it is a tool used by the designerSuggestion

Have a local engineer take the worst case scenario for your area and provide a design. The AHJ I work for did this and now all foundation walls require more steel #4 16" OC EW and J-Bolts 32" OC with 2x2 washers. Maximum wall length is 40 ft. Does not matter if it is a crawlspace or a 9 ft basement wall with a 3 story wood frame house they are all the same. Consistancy for the contractor and easier for us.

brudgers is sure to make hay with this one.

 

[mtlogcabin]

brudgers is sure to make hay with this one.

Yes I know it takes work away from theArch & Engineers

If a contractor doesn't want to do it that way they can follow the book or pay an Arch or Engineer for a design.

My point is the wall can be designed to resist the unbalanced backfill and thereby reduce the connector loading requirments to where 3 8d nails will work

I like keeping things simple and standard when it come to residential cookie cutter housing which is 95% of our residential construction.

 

[Mark K]

When a building official supplies the applicant with an alternate design so they do not have to hire an engineer I suspect that the building official will be accepting liability for the consequences of any problem related to that design. I do not believe that the normal governmental immunity will apply because providing the design is not an essential part of the governmental function. Check with your city attorney.

On the other hand if you were to adopt a local ordinance modifying the building code to allow the alternate design, assuming that your jurisdiction has the authority, then there should be no problem.

Ignoring the loss income for architects and engineers you may find that providing such a design could constitute a violation of state licensing laws unless the building official is a registered architect or engineer.

Regarding the earlier comments about others being ignorant of the limitations under which the building officials and inspectors work, which suggest that the designers should cut them some slack. I am not aware of plan checkers building officials, or inspectors going easy because the designer is under a lot of pressure. You have some obligations. If the jurisdiction will not provide the assistance necessary to fulfill the obligations that is the jurisdiction's problem.

 

[brudgers]

Agree 100% it is a tool used by the designer

See IBC 2306.1 and 2307.1 (2009). If it ain't prescriptive then the NDS standards become code requirements.

 

[brudgers]

brudgers is sure to make hay with this one.

Why? If a little reinforcing meets code, a lot must exceed it.

It's not as if there is such a thing as over-reinforcing concrete, is there?

The code is just minimums, right?

It never has maximums.

 

[ICE]

Why?

Does not matter if it is a crawlspace or a 9 ft basement wall with a 3 story wood frame house they are all the same.

If everything is built to the worst case scenario, time and material is being wasted.

 

[mtlogcabin]

If everything is built to the worst case scenario, time and material is being wasted.

The engineering cost can be more than the extra time and material cost. I am talking less than 2,000 sq ft retangular SFR that are 1 or 2 stories. The engineer was paid to provide an alternate design to the prescriptive requirements of the IRC. His stamp and signature is where the liability lies not with the city who allows it as an alternative.

 

[ICE]

The engineering cost can be more than the extra time and material cost. I am talking less than 2,000 sq ft retangular SFR that are 1 or 2 stories. The engineer was paid to provide an alternate design to the prescriptive requirements of the IRC. His stamp and signature is where the liability lies not with the city who allows it as an alternative.

This engineer...does he collect residuals?

 

[Sifu]

No IBC, no inspections for commercial buildings. May not make sense or be practical or in reality possible to not have anything but IRC (1-10) yet it is a reality. I see permits paid for everyday that will not be inspected. That is a political decision made by people that probably do not understand the consequences of their actions. I was hired to do what I am doing, I do it as well as I can under the restraints I am placed under. As for the specific question of the NDS, thanks to those who helped. I beleive the NDS is a designers tool, specifically excluded from prescriptive compliance and enforcement by the inspector as written in the words of ICC. I use it and many other resources to help me do the job but I won't present it as a prescriptive code to be followed. If I did that I might be "designing" and that I know I am not qualified (or legal) to do. In this particular case the prescriptive code gives an option for compliance. That option allows the use of the NDS (or in this case thanks to GB the WFCM) to calculate the shear strength of a connection as one possible path towards compliance.

 

[Mark K]

Does the state not have any regulations regarding building construction such as for public buildings or buildings over a certain size?

 

[Sifu]

There are some occupancies that get some oversight by the state inspectors. Where no local departments exist at all, or where it is minimal (like mine) there is no local adoption of IBC, etc. How and where the state gets involved is up the state. It was unbeleivable to me too when I got here but it is what it is. What we don't inspect far outnumbers what we do inspect and that seems to be the way they want it.

 

[brudgers]

If everything is built to the worst case scenario, time and material is being wasted.

I was being sarcastic. Concrete can be over-reinforced. http://en.wikipedia.org/wiki/Reinforced_concrete#Reinforcement_and_terminology_of_Beams