Connection w/bolts and welds?? Slip Critical?

[jakeh76]

In the Schaum's Outline for Steel Design on page 163 in the connection chapter it says if a connection is to be made of both welds and bolts that the bolts must be slip critical? Where I can I find this in the AISC mannual or codes? Are these to be "SC" because of possible load reversals due to such things as wind or live loads on buildings? Any thoughts? Thanks.

 

[SlideRuleEra]

In AISC Manual of Steel Construction, ASD, 9th Edition, look at the "Specification for Structural Joints Using ASTM A325 or A490 Bolts", in my copy page 5-270, para 5,(a),(5). Also in the Commentary on this section (page 5-302).

The assumption is that both the bolts and welds are required to carry the load, if there was any movement in the joint, the welds would fail. Then the bolts would be subjected to more load than intended.

 

[jakeh76]

Ok thanks, when I first read it I was thinking it meant that for a flexable moment connection that if the angle was attatched to the column with bolts that the angle must me attatched to the beam with SC bolts.

So this really means that the bolts must be slip critical if the weld and the bolts are connecting the same members?

So a Flex. momoment connection may be made with bolts attached to the column and a weld to the beam, w/o the bolts being slip critical? Thanks for the help.

 

[agrant]

You can surely use bolts to attach to the column and a weld to the beam without the bolts being slip critical. You need to consider the force level of your free body diagram and not so much the member level.

For example, on a moment connection from a beam to a column you could weld the shear tab to column, bolt it to the beam, have a top and bottom plate that is welded to both the column and the beam.

The rule is more that you can't divide one force between non-slip critical bolts and welds because they do not have the same stiffness.