Steel Joist Bearing Plate at Masonry Walls

[ron9876]

Where steel joists bear on masonry bond beams is the top of the masonry typically notched so the top of the bearing plate is flush with the top of masonry or is the bearing plate placed above the masonry.

 

[msquared48]

It depends on how the CMU courses work out. If the bearing line is uneven, you could have both conditions.

I most frequently see the steel joists resting on steel angle ledgers bolted to the CMU though if the bearing seat height varies, unless the joist has to cantilever beyond the wall.

Mike McCann
MMC Engineering

 

[ron9876]

Do you mean bearing on an angle attached to the face of the wall instead of bearing on the top of the wall? What type of anchors do you use to connect to the wall? Did you see my post a few days ago about the intent of ACI 530 for capacity of embeds into masonry? Would appreciate yur input on that also.

 

[msquared48]

Did not see your post the other day - I will look for it.

Usually the angle is sloping at the roof and I have found that the contractors want to use after-set bolts (expansion, not chemical) to minimize installation mistakes.

If the angle is level, then, maybe, maybe preset anchor bolts, but that's a pretty weak maybe.

Mike McCann
MMC Engineering

 

[jike]

I select the plate width so that it can sit down into the bond beam without having to notch the masonry.

 

[ron9876]

mssquared48--thanks for the input. Not much capacity with bolts into masonry if you account for joints. If you set joist bearing at high/low sides of roof can bear on wallls and eliminate heavy angle loading on a slope. Side parallel to joist slopes and this can still be heavy with heavy wind loads. Seems to me that some, not all, connections have to be chemical anchors if very large lateral loads. Looks to me like Powers wedge bolts have about the largest capacity when joints are taken into account.

jike--thanks for the input also. SJI requires bearing within 1/2" of face. How do you deal with this.

 

[jike]

Good question! I guess what I said isn't valid in light of the SJI requirement. The masonry will have to be cut!

 

[MikeE55]

For years I detailed the plates so that they were flush with the top of the U-block. Then I noticed the 1/2" requirement as a maximum distance from the face of the block. After this, I started showing the plates above the masonry to meet the SJI requirement.

 

[structuresguy]

I don't see how the 1/2" distance SJI specs has anything to do with whether the plate is flush or set down in a notch. All it refers to is that the edge of the bearing plate is not more than 1/2" from the face of the wall, so that the joist seat has steel to bear on close to the edge. That is all. Make you plates full width of the bond beam if you are concerned.

We typically use flush plates on top when dealing with bond beams. If we have a poured tie beam, then we will do either flush top plates or side mounted support brackets, which we weld to embeds cast into the tie beam.

 

[MikeE55]

The way I understand the detail the 1/2" requirement has everything to do with whether you set it flush or not. I don't want to require the contractor to chip the block at each bearing plate. This is why I would use a 3/8" plate and set it on top of the masonry shell in the plane of the mortar.

 

[ron9876]

I am in Florida and the uplift loads wouldn't let 3/8" work except for nominal conditions.