×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Lags into 2x nailers above and below wideflange beam, capacity question

Lags into 2x nailers above and below wideflange beam, capacity question

Lags into 2x nailers above and below wideflange beam, capacity question

(OP)
Hello!
I’m back with another wood connection question.
I’m working on a balcony attachment plate. The steel plate is ¼” thick. The original plan was to have it attach to the wood nailers at the top and bottom of the steel wide flange beam using lag bolts. It appears my loads are overstressing the wood(max allowable shear is 517#/bolt, and I’m getting 567 # demand/bolt).
My question is am I using the proper modification factors? I want to use a ½” lag in the middle of a 2x nailer. Are there edge distance reductions that I need to take?
As far as I can see, a ½” diameter bolt needs ¾” edge distance, which is centered on a 2x nailer, so perfect. Once I confirm my connection capacity, I will be able to update the plate size and number of holes.
I have used the AWC wood connection calculator to determine the capacity of the wood.
Thank you.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

I would not do this. No no no. This is a fairly critical application and would not be relying on lag screws into the side of a 2x nailer for permanent tension loads.

Can you get to both the top and bottom of the beam (top is more important in this application anyways)?

If so, I would be using a bent plate, and installing the fasteners through the top of the nailer. Much more reliable connection.

RE: Lags into 2x nailers above and below wideflange beam, capacity question


1) I don't believe that you can deliver shear to the low bolts without putting the bottom plate into cross grain bending which is ill advised.

2) I'm not sure that the stiffness of the sheathing is substantial enough that you could rely on your moment lever arm being the full beam depth.

3) I like jayrod's solution. At a minimum, at least install some 2x something vertical ribs behind the sheathing that would bear directly on the beam bottom flange.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

Quote (Bowsers)

As far as I can see, a ½” diameter bolt needs ¾” edge distance, which is centered on a 2x nailer, so perfect

No, not perfect!!
That is not a great detail. I would look at welding something to the I-beam and making sure it can take the torsion
or bolting a band to the web of the beam.
Installing lags into the skinny edge of a 2x4 is extremely sketchy for the following reasons...
They will never actually be centered.
Unless they pre-drill, the 2x will split.
The lower 2x4 will split anyway as soon as it sees any vertical demand
The lower 2x4 is forced into cross grain bending

RE: Lags into 2x nailers above and below wideflange beam, capacity question

(OP)
Ahh... OK, slight clarification. The whole plate is 1/4" and sits against the wide flange, so not relying on wood shtg to provide any load transfer.

I hear the concern regarding cross grain bending of the bottom load. The nailer is present as attachment to the soffetting, and I will check the capacity of the nailers attachment to the wide flange to transfer the load.

Using 2x behind the plate, and attaching it to the wide flange sounds like the best solution. Alternatively, (as there will already be field welding), would attaching to a traditional stiffener plate be acceptable?


RE: Lags into 2x nailers above and below wideflange beam, capacity question

A traditional extended plate would be the ideal scenario in my mind, I was trying to avoid site welding, but if it's there regardless, this is the optimal solution. But, the bottom flange should be braced against the inwards kicking motion resulting from the torsion.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

You could also infill Between the top and bottom flanges on one side and install thru-bolts as needed. No cross grain bending then. Just have to drill thru the wood and steel.

Mike McCann, PE, SE (WA, HI)


RE: Lags into 2x nailers above and below wideflange beam, capacity question

Quote (OP)

The whole plate is 1/4" and sits against the wide flange, so not relying on wood shtg to provide any load transfer.

My bad. You mentioned steel in the beginning and I just failed to read gooder.

What are you supporting here anyhow? Wood joists sitting on that 3x3 ledger thing? Notched? I thought this connection typology fell out of favor with the Carter administration. Or is the 3x3 steel too?

RE: Lags into 2x nailers above and below wideflange beam, capacity question

(OP)
This connection is to support an apartment balcony (DL = 12psf, LL = 60psf). Loads generated from Risa.

Per the contractor, the siding is 2" thick, and we will have a 1" gap between balcony and apartment. Hence 3" plate length.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

@Bowsers;

You have indicated previously that you are in a small office where the principal is rarely present.
I would strongly urge you to have him/her carefully review your design before it gets constructed.
One thing I would suggest is to, as much as possible, not using RISA to figure out your loads. A balcony should be easy enough to handle with pen and paper and you would likely get a better feel for things.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

(OP)

Quote (XR250)

I would strongly urge you to have him/her carefully review your design before it gets constructed.
Agreed - But I would rather have it go through 1-2 rounds of review than more. I've gone from doing a significant amount of concrete and steel to more wood in many recent projects, and I still don't have a strong grasp on wood connections.

RE: Lags into 2x nailers above and below wideflange beam, capacity question

Bowsers:
It is generally more instructive and constructive if you can sit with your boss, both looking at the same plans, details, specs. etc. Being able to do quick sketches, he says…, “no this won’t work, here’s why, try this,” etc. You can see when each other are not really understanding the other, etc. Your boss should know what you know, and what you don’t know, so he can give you proper guidance and keep you and the company out of serious trouble. If your boss is any good at what he does, you will learn and retain more by interacting with him, rather than going through this guessing game with us, here at E-Tips. Are there only two of you in the office? What’s with the other senior engineers, and experienced draftsmen, they can give you some guidance when a detail looks really crazy, they should see that? You and the boss should have regular review meeting to watch over your work and progress. This will keep you out of dead end paths and calcs. and make his final review easier, since he’s been involved all along. You also need to use some of your own free time to study the NDS, and a good wood design textbook, to show your willingness to really learn. Dig out some old calcs. and plans on similar projects, and study and follow them. Ask well thought out questions, never the same question twice. Good to the boss with good questions and with several possible solutions, and be able to explain your thinking on each, so he can quickly critique them.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close