Steel beam supported with a wood column: 1

[nuche1973]

Howdy all. I am working on a wood framed apartment building. The floors are wood joist on wood load bearing walls. The corridor between units is metal deck and concrete. Large open areas in the corridor are desiged to be W-sections on HSS columns. As a VE item the architect wants to change the columns to wood (to negate the fireproofing cost). Size and span are factors in the beam selection. Steel is best for the deflection issues (L/360)and available depth (9" after allowing for mech ducts, concrete & deck). Is supporting steel beams on a wood column (probably a parallam or similar)accepted? I'm using IBC 2003 and haven't seen a definiative "yes" or "no". Any comments will be appreciated. Thanks.

 

[nuche1973]

Forgot to add: siesmic cat. C and I did do a search and found information on masonry. thanks.

 

[BAretired]

Connections would be a bit of a problem, especially if you need to develop moment connections, but I see no reason why you cannot support a steel beam on a wood column.

BA

 

[msquared48]

I have done this too, but as mentioned above, no moment connection, simply bearing. However, I do usually use pipe columns.

Mike McCann
MMC Engineering

 

[nuche1973]

I am assuming then that this is one of those "engineering judgement" issues.

 

[nuche1973]

Ok, so then how do I apply this for multi-story buildings?

 

[BAretired]

You don't.

BA

 

[nuche1973]

Thanks.

 

[MiketheEngineer]

I have often used wood columns in wood framed walls with steel I-beams because they shrink and expand as the walls do. Steel/masonry won't move at all and this can be a source of drywall cracking. The tallest was 3-story.

Remember to provide a contnous path for the columns to whatever is below. We use "squash" blocks between sub-floors to transfer these vertical loads.

No complaints to date and have been doing so for many years.

Good luck.

 

[nuche1973]

Mike,
Awsome, thanks for the insight.

 

[dik]

BC, Canada is a seismic area and they are entertaining using wood for 6 storey construction.

As far as steel beams on wood posts, I've used 3/16" side plates and glulam rivets for holding the steel beam to the post.

Dik

 

[BAretired]

Well, bully rodger and peachy keen!

BA

 

[dik]

BA... I don't like the height that they are/have considered and there is a lot of dialogue among the engineers in BC. Connections are generally the components that fail in a seismic event and the added height makes this more critical for wood.

Dik

 

[nuche1973]

Thanks guys.

 

[BAretired]

dik,

I won't say that you cannot use steel beams and wood columns in six storey buildings, but I'm pretty sure it wouldn't be my first choice.

BA

 

[nuche1973]

Yup, the way it was explained to me was "It's not a good idea, but the code doesn't say we can't do it." Whatever, that means. I haven't gotten the hang of "legalese" or as my fellow field friends would say "engin-jargon".

 

[csd72]

I have no problem with supporting steel on wood columns and have done it on a number of occasions. I can think of no reason why this would be a problem and one good reason why it may be a good idea (as stated above).h

Beware cross grain compression on wall plates e.t.c.

 

[jhoulette]

Wood columns for steel beams is done all the time. However, you are wood column capcity is exceeded fairly quickly with multi-story building with stacking point loads.
The limiting factor is wood studs bearing on plates, a perpendicular to grain bearing area.
To help provide a good brace for the steel beam from rotation, be sure to provide studs the full width of the steel beam and a full height king stud each side.

MiketheEngineer hit on another good reason why to use wood studs when the rest of the structure is wood. I've done many 4 story wood structures and always use wood columns when possible. The lower levels tend to go to steel columns depending on the geometry of the structure. Also, when the main structure is wood and your columns are steel, you loose any bracing from the sheathing nails.

Beware of a 4 story steel beam and column system that will not shrink while the rest of the structure will...

Jim Houlette PE
Web:

http://www.evstudio.us

Online Magazine:

http://www.evstudio.info

 

[nuche1973]

Thanks for the information. However, I have to make another post about the shrinkage issue.

 

[dik]

Longitudinal shrinkage of wood is minimal.

Dik