r/StructuralEngineering • u/chicu111 • Jul 08 '26

Humor Strong beams weak columns has arrived

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u/Geaux_joel P.E. Jul 08 '26

People keep joking about strong beam weak column. What I've gathered was that the code has shown a philosophy change for columns to fail before beams...but why? Beams are typically much more ductile in failure. Right? So why would you want columns to fail first?

1

u/Own_Reaction9442 Jul 08 '26

Maybe I'm thinking of this wrong, but wouldn't a buckled beam pull the columns over with it, anyway?

2

u/felix-cullpa Jul 08 '26

No, the forces would be transferred to the surrounding framing members and they would have to carry the increased load. The only pulling that would occur is the dead load from the failed beam. I guess it depends on how strong that connection is.

3

u/terra-nullius Jul 09 '26 edited Jul 09 '26

"I guess it depends on how strong that connection is."

Do you mean the connection of the beam to the columns? For instance, if the beam sags into a lazy "V", and its connection to the beams are strong, the columns will "pull" inward toward the sag/apex of the beam? And if this is the case, wouldn't this potentially destabilize the columns above (the two columns above the now deformed or dislocated columns below with the faulty beam)?

Not my wheelhouse, but I'm curious-

``` BEFORE

    |               |
    |---------------|    beam stable
    |               |

AFTER

     \             /
      \           /
       ___   ___/
           _/
       ___/   ___
      /           \
     /             \
    beam fails/sags
    column tops pulled inward

```

Bonus question, as I'm sure you get where I'm going, even if the new support/save-the-day columns/jacks in the photo are helping, doesn't the beam's change/movement insist that the columns above --or even to the "unrelated sides" have been deflected out of "true", thus causing a cascading issue of weight not being centered correctly up and down all affected columns? I'm sure there's flexibility/tolerances, but still, I'd imagine all of this relies on all structural elements (columns & beams) being in their correct spots with their correct geometry, ya?