Repairing Macomber Joists

[ThorenO2]

Hello,

I see great information on here for Macomber joists, including the original catalogs. My question is what about repairing them? What are some of the things to look out for - looks like these are cold formed. The type I am working with are the prototypical ones used in the LOGO

. Looking to repair "kinked" bottom chords and a few detached webs that may have been hit since they were constructed some 60 yrs ago. Thank you for any input.

 

[r13]

The original catalog shall have member size, properties, and allowable stress listed (the one I saw limit to fb = 20 ksi), what specific work is to be performed on the old joist, and for what purpose?

 

[ThorenO2]

Thanks retired13 - it's an old warehouse that's seen abuse over the years. Looking at what type of methods can be made to reinforce the damaged components. No RTU's, just making the repairs for the new owner. Here's look at them.

 

[r13]

I suggest to engage an experienced structural inspection company to conduct a thorough visual/non-destructive inspection. Unless it has leaky roof, or subjected to harmful environment during past occupancy, I doubt there is significant damage present. Pay attention to end bearing though.

Also, is the building/joists are supported by wood posts? Fire safety could be a big concern.

 

[ThorenO2]

The columns are built-up sections using cold-formed C-shapes welded at the seams, no wood.

 

[r13]

I see quite a few conduit, or pipe running around, is there a sprinkler system?

 

[EngineeringEric]

Do you have a picture of the damage? depending on the damage and the demand it'll yield different repairs or maybe even no repair needed.

 

[ThorenO2]

EngineeringEric, I appreciate your input - here's a few shots with a worst case detached panel point and bent web. Mostly "kinked" bottom chords as in the picture with a few that have rotated - they didn't do a good job with bridging (non-existant).

 

[EngineeringEric]

Ouch! OK i agree that repairs are warranted here. however those are bad enough i'd actually want real repairs not my online opinion.

I would imagine repairs would look like retrofit webs to replace those that separated, and this may require a bottom and chord sister for connections.

For the rolled one... depending on load and condition, maybe x-bridging and additional bracing is sufficient? maybe load sharing and pull it back? it is the bottom chord so tension member except in wind.

do i think your roof is falling down today, no. but i would recommend that those be evaluated and repaired. call up a small local structural firm, i know we'd do this type of work any day. And my ideas are jsut initial thoughts, don't put much weight on them (the idea of those joists!! )

 

[r13]

Image the extreme force exerted to cause the damages and distort the joists, I would consider replacement rather than fixing 60 yeas old metal structures. The roof didn't collapse is simply it hasn't experienced the design level load event, but can't guarantee the event would never occur.