How to design frames of Butler Building?

[cclin]

Hi,all,

I recently have a project to repair the fire damaged of a one-story industrial building. This building is the so called Butler Building. Does anyone have any idea or any information or examples how to design the frames of this type of building? The span of the two columns of the one bay frame is about 96 ft long. In other words, the beam is of 96 ft span. The frames are spaced about 25' O.C. I was thinking of using the deep span OWBJ as the beam and regular wide frange steel columns to replace the existing frame. One problem (1) comes up is that How to design the connection of the OWBJ to steel column and how to detail this. Or any experienced engineer can suggest any other economic way to replace the existing damaged butler frames. The second question (2) is that what will the dead load and live load be. Should dead load 6 psf and live load 20 psf be enough? Will 20 psf live load too high? Will contractors stand on top of the deck during construction? If not, can I reduce the designed live load? The third question (3) is that the design table of roof deck by Verco is listed to about 14 ft. However, the frames are spaced 25'. Is there any vendor of roof deck producing decks that can handle the deck supporting points spaced about 25ft? Any help will be highly appreciated. Thanks.

 

[ajh1]

Your best source is to identify who the manufacturer of your building was and work with them in regard to replacement. "Butler" is a trademarked product name of Butler Manufacturing Co. and should not be used in the generic sense. Preengineering metal buildings are designed as rigid frames, swapping in a long span joist and mill sidewall columns may not give you proper lateral support. The typical metal building has secondary members called purlins which span the 25' between frames. Purlins are typically spaced on 5' centers, so your roof deck only needs to have a 5' span capability, not 25'. Design loads are per the applicable building code. For live loads, typically 12 psf on the frames, 20 psf on the purlins minimum. If you are in a snow zone these numbers may go higher. You also must be aware of wind load and seismic load requirements. A replacement of this nature will require a building permit and the approval of your local building official, so don't cut corners.

 

[jheidt2543]

ajh1 is correct, it is NOT a good idea to mix preengineered and conventional structural systems, particularly when you don't understand the design requirements.

If this is a fire damage repair and the building is insured, then the Owner is entilted to have the building rebuilt to its original insured value, in fact it MAY be a requirement of the insurance company. Insurance companies don't like "successful fires".

I would contact the manufacturer of the metal building and have them design a matching building frame and install that along with the other necessary componets. Then, the building will have a consistant framing system and be restored to its pre-fire condition. Since you don't understand the engineering aspects of a preengineered building, hire a local structural engineer.

 

[PT6FY]

Sound advice was given above. I worked for Butler and can tell you frames may have tapered columns, beams, changing web thicknesses, flange thicknesses, etc. It is difficult for even a local engineer to access and fix such damage. It should be familiar with analysis of such frames and products. Find out when the building was built, the contractor, who supplied the steel. It may be Butler, American Building systems, Nucor, Star, Inland or numerous other smaller companies. The local contractor who installed it would know the supplier. If very old or you just can't find this info out, then contact a pre-engineered builder and a good one will use a similar product to fix the affected area.

 

[AlohaBob]

Wow. You can't do this yourself. The liability is way too much for anyone but a licensed experienced structural engineer. There's plenty of ways to be involved, but not in this capacity.

 

[gwt1]

If it is not too late for input, I agree with PT6FY. I also worked for Butler until very recently and I can tell you that with the software at their disposal it would be much better to have them perform the anaylsis and/or redesign of substitute frames. It will save you time and you will end up with an accurate analysis.