Metal building modification

[FSS]

I have a metal building where the new owner would like to remove a center column. It looks like the column is part of the original building's endwall frame, and then the frame was left alone when another bay was added on (a full width frame in the newer part is next to this frame). So you have this single slender column in the middle of a big open space. As best I can tell the members in the old end frame, including the column in question, are w8x15's. I am assuming the end frame was designed for lateral and vertical loading.

I am thinking about creating a new larger frame and attaching to the inside face of the exisitng columns/beams, but that is definitely going to be complicated. Any better ideas on the column removal?

 

[jayrod12]

What about sizing a beam to run from outer column to outer column and then do a stub column from the roof beams at the peak down to this new beam although 38' is a long way to go.

If there is now another bay the lateral load should be next to zero and the vertical load should be minimal (depending on the roof framing) if there is a frame for the new bay directly adjacent to this old one.

 

[ajh1]

Is the new adjacent frame strong enough to hold up the 1/2 bay being supported by the frame where the column is to be removed? In many cases if that new frame is one of many in the extension it may have been made to support a full bay. Then all you have to have is some way to support the ends of the roof purlins that are currently being supported by the old frame. Most metal building manufacturers have a detail for load transfer between the old purlin ends and the new purlin ends although that is usually installed at the time the addition is made, not later. The old existing frame is suspect even with the column present as I would guess that it was using either brace rods or wall panel diaphragm to handle lateral loads prior to the addition. Without the paneling and no rods it has minimal lateral resistance. The adjacent frame is obviously helping but again may have only been sized for a 1/2 bay of lateral load if the existing frame was assumed to continue carrying load. In some cases the manufacturer is told that the old wall paneling is to remain, then somewhere down the line the paneling gets removed because it is in the way without anyone thinking about lateral forces.

 

[BadgerPE]

Is this column directly below the original frame? We work with a particular PEMB manufacturer that when they put these endwall columns on, they have something of an offset connection so that no gravity loads are transferred to the column. The column is simply there to attach the girts to and to take the out of plane wind load on the wall surface. Depending on what your roof loads are, this may be the case as an 8x15 is a pretty small column to extend 22+ feet and carry significant gravity loads while only being braced by girts. If the girts have been removed, then removing this column may not be a problem. However, a thorough analysis of the existing frame w/o center column will need to be performed to verify that the column can be safely removed.

 

[SteelPE]

From your sketch I would disagree that it is an end wall column (maybe you can tell otherwise from being onsite). It looks like this is just a column in the middle of one of their frames. When you add these columns in, it greatly reduces the lateral "kick" forces induces by gravity loads. These columns are often bolted to the underside of the main frame beams.

I had a similar problem proposed to me a few months ago (removing a center column in a PEMB). The client wanted to replace the column with a beam, they call it a "jack beam". I was concerned that the change in stiffness from a column to a beam would produce a "kick" force in the other columns and the foundation would be undersized. I discusses my problems with someone who used to work in the PEMB industry and he said that while I was correct with my concerns, they never gave it much thought and would just size the center beam to carry the loads appropriately (with out concern for stiffness other than what is in the code). He said that his name was on hundreds of these "jack beams" that came after the fact and he has never received a complaint about one failing.

 

[msquared48]

Are you sure this is an end wall frame assembly (which would have been used if expansion was envisioned in the future), or just an end wall? Is there a moment connection at the intersection of the purlin to the outside wall column, or is it just a pin connection?

Mike McCann
MMC Engineering

 

[haynewp]

I would try to find the original PEMB mfr and contact them. Look for any markings on the building and ask around.

You can then likely find out if it is an expandable endwall and possibly come up with a better solution if the column needs to be removed. Do you have existing foundation information?

 

[FSS]

I probably have the names mixed up as I know the pemb industry has their own nomenclature. Frame is a poor choice, and this is probably what is left of the orginal end wall (there is a joint in the concrete showing the break from old to newer secitons). No drawings are available and no markings on the steel are visible. The member sizes are clearly smaller than the other "frames" so I can't imagine there was any lateral ability without end panels or diagonals.

 

[msquared48]

Then it is just that, an end wall and not an end wall frame. Treat it as such.

Mike McCann
MMC Engineering