Structural Analysis

It connects the two columns together so they act compositely. To do this they effectively act as 'shear connectors' joining the two columns. I no longer have any literature on the design of these 'ties' but they are slightly less stiff than a real welded connector. Not common today, but I've seen them connected with rivets.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

The columns are the chords of a truss. The connecting members form the web. Analyze them accordingly.

I recall earlier work, where laced columns were treated differently than a truss. I couldn't find the old info... calculation of the section properties was provided and it wasn't handled as a 'truss problem'. I do recall the caution about it being less stiff than if it were rigidly connected based on the flexibility of the web members not being solid shear connectors. I've not looked at a laced column for more than 30+ years... I guess they still do them.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

Well, the chords are continuous, so they would not be treated quite the same as a pin jointed truss, so it could be designed as a frame. I believe that assuming a pin jointed truss would be conservative, but I have not designed any laced columns recently either.

What does the beam connection to the tops of the paired column groups look like? It would be nice if that was such that the columns were loaded only axially, and equally, with no prying effects on the paired column groups. In that case, I believe that the common design strategy is to treat the lattice work as little more than weak axis bracing for each axially loaded column. The idea is that the strong axis flexural stiffness of the truss that you create dwarfs the weak axis flexural stiffness of the individual column shapes.

Also, with the beam running over both columns, what laterally stabilizes the tops of those columns? I'm used to seeing the two columns arranged perpendicularly to what you show such that one supports the axial load of the beam and the other runs up to a roof diaphragm.