Combined Welded and Bolted Steel Connection 2

[abusementpark]

If I am making a wide flange beam to column connection and I provided a CJP weld at the flanges to develop moment, am I allowed to provided a bolted web plate connection as well to take the shear force?

I remember reading somewhere that you can't do that, because you may have to fail the welds in flanges to engage the bolts in shear at web.

 

[sandman21]

So you model the grout? How much do you assume is there? Model the concrete? Assume it crushes? Elongation of the bolts? Elongation of the plate washer? Slip of the headed bolt in the concrete? Do you consider the effect leveling nuts? Does this crack the concrete? How does this effect anchor slip? Do you model any restraint given from the slab?

 

[abusementpark]

I think what sandman21 is getting at is that you cannot make everything in this business an academic exercise. You'll go crazy while killing the budget.

I do not believe the "pinned base" assumption has yet proved to be one of any serious consequence.

 

[KootK]

I agree, everything cannot be an academic exercise. However, I too question the pinned base assumption in many situations.

My company has standard "pinned" column base plate details. They show the bolts clustered at the center of the column section to reduce the moment transfer.

In my opinion, this just exacerbates the prying / tension forces on the anchor bolts that don't know that they're not supposed to be restraining column rotations. Then they fail prematurely and indeed become pinned. Of course, baring the provision of other transfer mechanisms, you've also lost your ability to transfer shear through your pinned base. Ouch.

I get nervous about assuming a pinned condition unless the failure mode of the bolts is bolt yielding. And it's tough to make that happen with practical pedestal dimensions and the Appendix D stuff.

Some folks in my office will do a little of both. They design the frame assuming pinned column bases and then design the base plate to take 50% or so of the expected moment were the base fixed. The 50% is entirely arbitrary of course.