W10X39 Bottom Flange Plate Stiffening, in Place

[Blooongeey]

Apologies in advance if this topic has been covered. I did make an effort to find a similar thread, but an found only slightly similar scenarios, most likely due to the descriptors.

An existing W10X39 spanning 20' is to be stiffened in place due to the addition of load. This is a residential application, and only the bottom flange is accessible. Calcs indicate a 3/4" x 10" wide plate along the middle 10' portion of the span will bring the section within deflection limits for the added load. Stitch welding using 3/8" fillets are specified according to the shear flow calc'd.

Fabricator has expressed concerns of potential negative(downward) cambering after welding, as the top flange is not accessible to heat for the purpose of controlling warping.

Any guidance/thoughts/tips would be greatly appreciated here.

Michel Blangy, P.E.
Redondo Beach, CA

 

[dik]

Catch the attached... if you have Smath.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1632238806/tips/Comp-W_PL_kdsnry.pdf[/url]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1632238807/tips/Comp-W_PL_szk2b0.sm[/url]

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[SlideRuleEra]

An existing W10X39... only the bottom flange is accessible.
... 3/4" x 10" wide plate...

A W10x39 flange is 8" wide, the proposed 10" wide plate will extend 1" beyond the flange on both sides. Weld will have to be performed from above the plate. Is there enough clearance between the plate and ceiling to make this possible?

 

[jayrod12]

You would want to jack the existing beam up to remove the stresses and maintain that position during the strengthening procedure.

 

[Blooongeey]

My apologies, I do not know how to properly quote a poster, but ..

SlideRuleEra (Structural)21 Sep 21 16:16
A W10x39 flange is 8" wide, the proposed 10" wide plate will extend 1" beyond the flange on both sides. Weld will have to be performed from above the plate. Is there enough clearance between the plate and ceiling to make this possible?

As the W10X39 has a 3X plate along the top flange, and the floor system is 2X12 repetitive members, it hangs down just enough to allow for welding from above the flange plate being added.

 

[dik]

Just be careful, wood and welding do not go well together...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[SlideRuleEra]

Blooongeey - Believe you have a good, workable modification. Omer Blodgett's ""Design of Welded Structures" has recommendations for "wide" cover plates (see attached .pdf file). Take a look at the one about not welding near the cover plate corners. Stitch welding seems a good compromise considering (indoor) working conditions.
Take jayrod12's advice about jacking the existing beam.

 

[Blooongeey]

Thank you to all who contributed. Michel