Preferred beam width in relation to column width for ease of construction 2

[xp1]

I believe I remember reading somewhere that contractors prefer beams that are a different width than the column they are framing into for ease of construction. However, I can't remember the reason behind this. So first off, is this true? Should the beam be smaller than, the same size as, or larger than the column it is framing into? And does it depend on the amount of beams framing into the column? Thanks for any info.

 

[MotorCity]

If the beam is narrower than the column, it makes the formwork easier than if the beam is wider than the column.

 

[EngineeringEric]

For concrete beams: Yes, this way the beam rebar does cross through the center of the column's
For steel: Not sure there is a general rule. I have framed into smaller columns but the connection matters (think moment frame)

 

[xp1]

Sorry, I should've clarified that I was asking about concrete beams. Thank you both for the answers!

 

[JAE]

Here is a CI article about this topic:


Check out Eng-Tips Forum's Policies here:
faq731-376

 

[MotorCity]

I guess the answer depends on who you ask. The article posted by JAE suggests that beams wider than columns are less costly to form. My experience has been just the opposite. Contractors I have spoken to would rather have the beams narrower than the column. This allows the beam formwork to simply dead end at the column.

 

[jdcollins]

I'd have to disagree. In our experience, beams wider than the columns work better. Generally the formwork is easier as there are no faces of the concrete column exposed through the beam depth. Further, the outer beam steel can continue past the column steel and only the middle steel needs to be threaded through the column steel.

 

[MotorCity]

@ jdcollins: Not sure the formwork is much easier, the bottom of your beam formwork needs to be framed around the column.

You also need to be careful using wider beams. If they get too wide, you may have torsion issues with the portion of the beam that runs past the column as that edge of the beam is unsupported.

 

[JeanLucPicard]

Agree with EngineeringEric!

I always make columns stronger (lower capacity), beams weaker (high capacity, so they are commonly smaller). In case of reaching stresses beyond ultimate limit state, beams fail, columns stay. The structure that way may keep its integrity, however, if columns fail. I don't want to think about it. Sometimes I think that we have simmilar jobs with human lives as doctors do...

Live long and prosper!

 

[BAretired]

It usually takes longer for us to bury our mistakes.

BA