Curious as to the actual use of this memebr?

[Apexpredetor]

I have had a debate with other engineers in our office about the function of this member. See attached sketch. I am talking about the red member I have labeled "splice"

Can anybody elaborate?

Thanks

 

[Triangled]

1st of all... 8" x 16” oak beam!! Wow.
Perhaps someone felt a need for a tension resisting connection beam to beam, if I'm understanding your drawing correctly.

 

[fegenbush]

If the beam was designed as a continuous member, the splice would be necessary to resist the negative moment over the column.

/I also echo Triangled's comment about the seemingly excessive nature of the beam material.

 

[Apexpredetor]

It is an old industrial building with another floor above, tunred into offices and mixed use. It is three spans. Two outside walls (masonry), and two composite columns.

A few of these "splice" members are broken at the nail locations.

I am thinking that they were installed to resist longitudinal movement of the beam away from each other? Basically, to tie them together, but with little or no moment resistance.

 

[racookpe1978]

Well, they are wood splices over a steel plate at a break in the main wooden horizontal beam. OK, sort of makes sense - if you assume the steel plate needs to be supplemented by a splice across it to carry vertical loads. Certainly it will not - as pointed out above - carry moment loads.

or, it did "try" to carry moment loads at some earlier lifetime of the wooden building, and the splices failed utterly at their nailed joints.

So: Leave the splices as-is, but clean them up and get rid of the nails! They are splitting the wood beam right where the load is the most (over the steel plate at the column) and they are splitting the wood splices. Bolt through the wood splices and the wood beam and clamp the joint tightly together. Epoxy or glue it? Not sure if that will help unless you can clamp the glue and split ends all together while drying.

Is every one of the steel plates in good shape? Not bent, not rusted, not distorted or itself splitting or slipping? They are what is holding up the second floor.

 

[Archie264]

I hate to tell you this but as shown that (those?) 2x12's are inadequate to do much of anything other than possibly provide a bit of tension capacity, depending on how it's connected. It (they) certainly will not provide enough capacity to convert those simply-supported beams into a continuous beam.

Is this an existing condition or a proposed retrofit?

 

[Apexpredetor]

Existing condition. I consider it simply supported beam/column configuration.

I was assuming it was only there for tension purposes longitudinal to the beam.

Steel plates are in good shape. Looks to be a recent (within the last 40-50 years) renovation where the wood "keystone" was replaced with a grout/concrete one, the columns used to be wood, and cast iron plates replaced for steel.

 

[jittles]

Not knowing anything else about the structure, the beam might be acting as a chord or collector element. Keystone/grout block for compression due to the beams not butting up tightly and wood 2x splice for tension along the beam line.

 

[AELLC]

All modern wood framing uses Simpson strap ties to tie beams together. Plus, wood shrinks a bit axially. With such massive beams, the tension force induced into the ties could be very large.

Typically, for normal wood construction (SFR), I use Simpson CS18 x 2'-6", both sides.

 

[Apexpredetor]

This is an old building where the owner was (I assume) trying to maintain the original look.

 

[woodman88]

From the picture, I would say the 2x12's are meerly being used to support the planks until the new keystone dried. Then just left in place rather than being removed.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[Apexpredetor]

The planks were there on original build using the wooden "keystone". I will try and find an image of the original setup.

 

[AELLC]

If the 2 x 12's don't actually tie the beams together, what else does? Is this in a seismic region?

The "antique look" could be attained if you use specially detailed straps of at least 3/16" thickness, and paint them some color other than silver. Use lag screws rather than nails.

 

[Apexpredetor]

No, not is a seismic region.

 

[SLTA]

Old - that's the key. This is typical in old mill construction. I've attached a picture from a old book I have (the original bookplate says 11/1/13, 100 years ago!) called The Architect and Builder's PocketBook, and if you look hard, you can see at each beam connection over the columns, there is a strap shown.

 

[SLTA]

here's the title page of the book:

 

[Apexpredetor]

Bingo! Exactly what we have going on here.

Is that the name of the book the image is from? The Architect and Builders Pocketbook?

Thanks

 

[SLTA]

yep, sure is. I bought it in a used book store in Boston about 14 years ago.

 

[msquared48]

I have also seen vertical round metal dowels welded to the oak beam bearing plates to act as horizontal tension/lateral constraint ties.

You might want to do a scan on the bottom of those beams from the side. If those dowels are present as I suspect, you may not have as much of a problem as you think.

Mike McCann
MMC Engineering

 

[Apexpredetor]

Thanks guys. I was just suggesting we could perform the same function if we had a steel pin or dowel.

Much appreciate all of the help.