Residential beam sizing for deflection 3

[Rigger12]

I'm currently sizing a beam to take out a load bearing wall in my own home (to open up between the kitchen and dining room) and have a couple questions about how you size for deflection limits when removing an existing wall, on new construction we size for live load deflection as the dead load deflection wont effect the finishes, but since this is a finished structure should I size the beam to deflection from the combined load, otherwise when we put up the beam and remove the supports the beam will deflect and the upper floor will settle from the dead load deflection and could mess up some finishes or the levelness of the floor above. The span is 16'-6", and it will support a bathroom on one side with a 14' joist span and a bedroom on the other with a 12' joist span, so the tributary width is 7' from the bathroom and 6' from the bedroom, also there is a partition wall that is not load bearing above the existing load bearing wall.

I am getting a live load of 460plf and a total load (live + dead of) 745plf with everything considered (40psf LL bathroom, 30psf LL bedroom, 15psf deadload both in case we ever switch to porcelain wood look tile in the bedroom, plus a few other loads we have), I'm winding up with a 14" or 16" in parallam beam, which I likely won't do because it's 2x8 framing on the floors and we don't want the beam sticking down that far. The limiting factor is deflection limits, not moment or shear. So the question become because it's a long span with tile above in the bathroom do I use L/480 or L/600, and do I use live load deflection or total deflection, L/480=.415" L/600=.33 inches, I'm worried if I size for live load when we remove the supports any settling will disturb the floor above.

Am I being grossly over conservative by sizing for L/600 for total load deflection. Since it's my own home I don't want any chance of the floor bouncing or settling, the house was already built cheap by the builder in the 80's and I'm been improving everything in it as I've been living there.

It seems no matter what I'll have a little of a bump down in the ceiling where the beam is as it's only 8" framing and I'll have to go with a W8 of some weight. I don't mind sizing it a size up as I will be supplying and furnishing the steel myself, just curious for any input as I don't really do any residential work.

 

[XR250]

"MetwoodBS". - might want to change your handle!

 

[XR250]

I'll admit to generally being hesitant to spec 3rd party products. Often the marketing material will make bold claims overstating what the product can do, which you only realize after spending hours reading the fine print or some evaluation report. I've been burned on this enough times that I'm now naturally hesitant.

Same here. Also, frequently when they send me the calcs on the product, I find too many liberties taken or issues not addressed

 

[MetwoodBS]

We have performed testing at Intertek and NTA. We provide engineered "Beam Sheets" with each one of our products and it is sealed by a licensed engineer. We have been fabricating our joist and beams for more than 25 years.

We roll our Cold Formed Steel products 7 1/4, 9 1/4, 12, 14, 16 to match several of the wood depths. I can get 11 1/4 also, but more residential customers are using 11 7/8 versus 2x12.

I know we have some issues on our website that are not working properly. I apologize for the inconvenience. We have been building a new site and will be launching within the next week.

We are in the process of working with the Home Innovation Research center and IAPMO to achieve a Code Compliance Research Report.

If you have a sample loading or a beam in mind, feel free to send me an email at scallahan@metwood.com and I can send you over a sample beam sheet. I know XR250 asked about a W8x18. I can build a beam in 7 1/4 depth or 9 1/4 depth and the price varies based on stiffness requirement.

I have attached a copy of a Beam comparison between on of our 14" Beams and a triple 24" lvl.

Metwood.com

 

[XR250]

I know XR250 asked about a W8x18. I can build a beam in 7 1/4 depth or 9 1/4 depth and the price varies based on stiffness requirement.

W8x18 I = 62. Price + shipping for the 9 1/4" Equiv.

 

[Eng16080]

Metwood, Thanks for all the information. What are the general material properties of the beam? I see it's light gauge. Is it using 50 ksi steel (yield strength)? Is the steel being rolled into tube sections which are then welded closed (like an HSS)?

In the interest of this particular thread and OPs original question, would you be willing to provide a calculation for a 16'-6" span beam with DL=195 plf and LL=460 plf?

 

[XR250]

The beams appear to be "C" sections. How are the ply's connected together to transfer unequal loading shear?

 

[MetwoodBS]

Eng16080 Do you have a requirement for LL Deflection? Is their a Height Restriction? I can do the beam in 9 1/4 I went ahead and attached a 9 1/4"sample and a 12" sample.

XR250 and ENG16080 - We use Cold Formed Steel C-Studs that are 50 ksi steel and weld A706 reinforcing steel to the corners of the web and flanges to add additional strength. We weld two Studs together at the flanges to create a box beam. We change bar sizes based on loading and deflection criteria. In the attached example the 9 1/4 beam contains internal #9 bars and the next post the sample 12" beam contains #6 internally. We can also add additional plys if necessary due to height issues.

We place a rebar grid at the ends to handle shear and allow the beams to be trimmed in the field up to 12" off each end.

For the example for Eng16080 - I could fabricate a beam that is 18' with one or both ends trimmable so the product is on site while they are framing. I can also cut to length. However, things sometimes vary and having it too long is better than to short.

Metwood.com

 

[MetwoodBS]

Attached is the 12" sample for ENG16080 request.

Metwood.com

 

[Eng16080]

MetwoodBS, I meant for the beam to be 7 1/4" deep to match OPs floor depth with deflection criteria to also meet what's indicated in the first post (if that's possible). But what you sent should be sufficient for us to get a better idea of this product. I'm not intending to make you do a million calculations here.

 

[XR250]

We weld two Studs together at the flanges to create a box beam.

So if they are welded together in the factory they are ultimately going to be heavier than the red iron I-beam equivalent due to its shape being more efficient.
So where does the economy lie?
Still looking for a W8x18 equivalent to compare.
An 800S200-97 has an I of 11.2 and weights 4.3 plf - so need say 6 of them for equivalency to a W8x18.
The weight would be 26 PLF and it would be 12" wide. I do not see how this is practical or saving money.

 

[MetwoodBS]

Here is the 7 1/4 sample. I would need to camber approx 1/4" to avoid adding a 3rd ply.

Metwood.com

 

[MetwoodBS]

XR250
My 7.25" x 5" beam to carry the load is 19.9 lbs a foot
My 9.25" x 5" Beam to carry the load is 20.9 lbs a foot
If you have the room, my 12" beam is only 14.7 lbs a foot.

The difference is the connections. All connections to my product are made with self-drilling screws. To connect to a W beam you either have to use Powder Actuated Fasteners or Bolts, which require a lot of labor. If a w beam is flush, then you are required to add several lays of wood that has to be ripped to the correct size and then through bolted to the web.

If you just compare cost, I may not be as inexpensive as a W8x18. However, if you need to attach or cut to length, then the labor cost is much less. We have framing contractor request our product over W beams and Engineered wood so they don't have to build them onsite.



Metwood.com

 

[Eng16080]

MetwoodBS, Thanks for the calculations. A few quick questions:
[ol 1]
[li]"Deck Connection: Nailed". Are special nails required to fasten to the LGS?[/li]
[li]"Design assumes continuous lateral bracing for both flanges." Is this the case even if the beam is simply-supported? I would expect only top flange bracing needed in that case.[/li]
[li]"Web stiffeners are required at all bearing and point load locations unless reviewed by a design engineer." You mentioned that the beam would be supplied with web stiffeners, or am I missing something?
As you mentioned above, I'd be worried that this would get missed in the field if not supplied with the beam.[/li]
[li]It's perhaps irrelevant, but the software output is a bit confusing in listing the Live and Dead loads as 40 plf and 15 plf. I think it should read as "psf" instead.[/li]
[/ol]

 

[Eng16080]

I think you answered my question #1 above. I assume deck is to be attached with screws, not nails.

 

[ChorasDen]

Choosing my words carefully, if anyone intends to use a product manufactured by Metwood, or a similar manufacturer that does not provide an ICC-ES code evaluation report, I would strongly suggest characterizing the product as a deferred submittal item, and requiring sealed analysis of the product prior to including it on your designed plan set. I have no experience with the TuffBeam product, so I am unable to speak to it, however, some of the repair options provided by Metwood appear to play a little fast and loose, and if I was asked to review it by a GC, I would expect evidence submitted as well as a sealed set indicating adequacy of the repair solution for each specific design condition, similar to truss repairs.

 

[jerseyshore]

Do people normally approve products without ICC reports? No ICC report is a no-go for me. In NJ the building officials don't know anything about structure, but one thing they do ask for is code approvals on specialty or not-so-popular products.

 

[XR250]

7.25" x 5" beam to carry the load is 19.9 lbs a foot

I find it hard to believe this is equiv. to a W8x18. Can you show me some section properties?

As far as attachment goes, many times contractors just notch the joists into the web of the W8 and then block between so no fabrication is required.
I only see these useful for use floor systems or ridges where things need to be totally flush. For most ridges and garage door headers or other situations, taller LVL's work fine and are much cheaper and easier.

 

[StrucPatholgst]

Do people normally approve products without ICC reports? No ICC report is a no-go for me. In NJ the building officials don't know anything about structure, but one thing they do ask for is code approvals on specialty or not-so-popular products.

Samey sames, jerseyshore. I'm in north jersey, and I wouldn't spec a product that didn't have an ESR report unless I was designing it myself, or it came with a calc package with a raised seal. I don't want that liability.

 

[jerseyshore]

I just recently had a building official (one of the Amboys or Woodbridge I think) ask the contractor to bring a box of unopened carbon fiber straps along with my letter/ drawing to prove to them what product they were using on-site. It's literally the only time building officials give a shit about structure in NJ. I even had a building official call me to ask if an architect can size a steel beam or if it needs to be an engineer . Would be a fight to get something like this thing approved that's for sure.

 

[Rigger12]

Looking at the numbers provided in Metwoods example for the 7 1/4" beam for my situation, I dont see how it's better than a double MC 7x22.7, I have a 13' triburaty width, LL 40psf, floor DL of 15pf and I added an additional linear deadload laong the beam for a partition wall located above the beam location, so I have a Live Load of 520plf and total load of 790pfl, with the MC 7x22.6 I get LL deflection of 0.3144" which is L/627, Total deflection is 0.4792" which is L/413, like I said I was attempting to keep total deflection under L/600 if reasonable, with a W10 or W12 it is.

The Tuffbeam example given is showing LL Deflection of .5292" and Total Deflection of .7764", even with a 1/4" camber I don't see it outperforming the MC7x22.7 based on these numbers.