column bases with large moments 1

[KZF1]

I am designing a stiffened column base plate per "The Design of Welded Structures" book written by Omer W. Blodgett, specifically the detail per the attachment.

Can anybody help me with a couple questions?

1. What is the correct method in determining the base plate thickness when using this detail? I'm assuming AISC Design Guide #1 does not apply because of the stiffened elements welded to the column??
2. Why is there a gap shown between the bottom of the stiffening channel and the top of the base plate in the attached detail?

Thank you!

 

[KootK]

1) Much of the design guide stuff will still apply. Consider that, compared to a regular base plate, not much has really changed on the compression side of things. The main difference is that anchor bolt tension is no longer required to be transferred through the base plate.

2) Frankly, I've always wondered about the "gap" myself. One explanation is that natural cross section tolerances in the channels would preclude a tight bearing fit. Additionally, the base plate to column fillet welds, if present, would interfere with channel placement. Another explanation is that the flow of forces is more predictable with the gap. Without the gap, some of the anchor bolt tension would probably be flowing through the base plates.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BAretired]

The gap is explained in the article. Read the last paragraph.

BA

 

[KZF1]

BA,

Was there supposed to be an attachment to your response? Thanks.

 

[KootK]

The last paragraph that BA referred to is the one in your attachment KZF1.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BAretired]

KZF1,
The article I mentioned is the Blodgett article which you attached in your post. The last paragraph explains why the channels were set clear of the bearing.

BA

 

[KZF1]

Thanks for the input. Much appreciated!