Need to Extend a Steel Beam by 6 Inches 1

[jamie2000]

We did some measurements on an existing building that was to be expanded vertically. The new steel beams (W8x24 spanning 17 feet) were to be supported on one end by new steel columns spliced to existing columns and at the other end on an existing brick wall. Unfortunately our measurements came up 6 inches short for a couple of beams and now we are under the gun to fix the problem. Does anyone have any suggestions of how to extend the beams? My first thought was to extend the beam web by adding a plate to it (basically extending the connection by 6 inches.

Thanks

 

[JAE]

You can extend the full cross section of the beam - this will require a full penetration weld splice.

Another would be your suggestion to extend the web plate - but be careful as the web of your beam isn't very thick. If you extend the web, and the bottom flange for bearing, you create a compressive force in the web along the edge which is subject to buckling.

Whatever you extend, must be properly welded/connected to the end of the beam and the extension and connection both have to take the shear and moment that results at the 6" point.

 

[evelrod]

This post comes under the heading of 'been there, done that'! The correction depends a LOT on where you are located and what the structure covers. I am in the Los Angeles area and the codes are rather strict, however they allow a full penetration welded extension , but the min. is 12 inches. Just cut back 6 and add 12. This is a rather small beam, so this repair should be expediant.
On some occasions I have added splice plates to extend, but the plates were 1/2 in. material and flange to flange fit. The time involved in making the plates and either welding them or alternately bolting them became excessive.
Soooo, I still would weld a piece on, even though in my area it requires a UT test in most cases.


Rod

 

[bengineer]

Sounds like you're coming up short just like the Jamaican bobsled team.

It may be possible to weld a seat type extension onto the beam similar to a bar joist bearing; just make sure the welds can transfer the moment and shear occuring at their connection to the W8.

 

[redhead]

I think bengineer has the right idea.
Assuming 50ksi steel, a W8x24 spanning 17 feet can carry a maximum load of 27 kips, and the reaction at each end, assuming UDL, would be 13.5 kips. Allowing 3 inches to the centre of bearing on the masonry, the moment at the splice point would be 13.5(3+6)/12 = 10.1 kip-ft.If you weld a C5x9 to each side of the web ( S = 7.12in3 ) resulting bending stress in the channels will be 17.0 ksi. This is a worse case scenario. I expect your actual loads are lower.

 

[idl]

At material prices of about $0.40 (Canadian) per pound and union wages somewhere near the Moon, how much would it cost to buy a couple of new W8X24's?
Kind regards,
idl

 

[evelrod]

idl---Let us assume that all the necessary material is on the jobsite for convenience and also assume the necessary personnel and tools are there, logical.

Setup , layout, cutting and prepping for weld two W8 X 24---two men 1/2 hour---weld, grind and prep for inspection 2 men one hour---total approx. 3 man/hrs. @ the T&M rate when I retired in '98 of $54/hr. (Los Angeles)---$162 add in about $60 for inspection (depending largely whether you have a resident inspector) approx. because it varies from company to company. Total $222. This is real world stuff here, guys. Even when you DOUBLE the estimate and ADD 25% (The 'BETHLEHEM' method) you end up at $555. Last time I got a couple of small beams fabricated and delivered from a steel fab shop (it was a non-union shop, at that) the cost was higher and I had to wait TWO days (while my men were still on the job)! Also, if you are doing it yourself you will save a bit on the T&M costs which are probably much higher in 2002.

I am not sure if this little ditty is any help to anyone, but I needed to put my two cents worth in for the Union personnel whose wages are NOT somewhere near the moon these days (Consider my daughter, 30 years old, high school, 1 year of Jr. college @ $52,000 salary (plus benifits) as computer help tech for Kaiser Permanente who daily DOES NOT have to risk her life for her job)! Incidently, her hubby IS a union Ironworker and makes about the same @ $58,000 +/- per year plus his benifits.


Rod