3/8" Plate Design 5

[MaxMedic]

I am trying to figure out if the 3/8" plate can handle the moment and deflection from the weight of the brick on the angle that is welded to the plate. I do not know how to approach this.

The plate and bolts are spaced at 16", I already have factored the spacing into the loading from the brick.

 

[DaveAtkins]

The plate will try to bend to the right, below the slab. Deflection might be an issue.

You are applying a moment at the end of a cantilever beam. I don't see that exact situation in Table 3-23 in the AISC Manual. I would model it using RISA3D or a similar program.

DaveAtkins

 

[dik]

If you need 7/16 angle, then the plate should be 7/16, unless the 7/16 is for deflection... moment diminished from attachment at the angle to the anchor at the top. Your anchorage looks fairly massive with 3/4" @ 16. can you safely attach to the backing? are you going into masonry? You might want to look at adhesive anchors and slightly smaller diameter.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[MaxMedic]

I do not have risa3d or a similar program.

The anchoring is pretty big. It’s anchoring into a 9” structural slab every 16”. There is a plate with a bolt every 16”

 

[rb1957]

The most important dim'n is missing ... the distance of the load from the plate.

and "0.6K" is IMHO a bad way to write 600 lbs ... I first thought you meant 0.6kg.

another day in paradise, or is paradise one day closer ?

 

[KootK]

Actually, scrap that last sketch. I didn't notice that the angle hangs lower than the slab soffit.

 

[MaxMedic]

Sorry, the distance of the load to the plate is about 7 inches

 

[XR250]

I second that deflection may be an issue with a 3/8" plate.
If you don't have software, maybe find a formula for a propped cantilever beam with a moment on the end.

 

[MaxMedic]

I found a formula for deflection at a cantilever beam with a moment. The middle diagram of the attached. But, what would my max allowable deflection be?

 

[BAretired]

More important than deflection is rotation, but perhaps they are both important. It is a matter of simple statics, but the detail is pretty bad. If you need a 7/16" leg 16" long to carry 16" of brick, why on earth would you use a 3/8" plate, 4" long to carry the same load, with an even greater eccentricity?

BA

 

[phamENG]

This is going to be an iterative solution:

Maximum deflection is based on curvature to prevent the mortar joints from opening too far as the mason lays the brick and then to prevent cracking after the mortar cures. L/600 is the vertical limit. In your scenario, the lateral deflection of your hanging plates contributes to the vertical deflection of the bearing point of the brick on the angle. So you don't care so much about the deflection of the angle as you do the global deflection of the toe of the horizontal leg of the angle.

So first assume that each hanger is a point of zero deflection on your angle. Calculate deflection of the angle due to bending and torsion and check strength. Deflection of our point of concern should be well below L/600, since we're going to be adding more displacement shortly.

Now put that torsion into your plate as the end moment. Check the strength of the plate and the lateral deflection. You'll also need the slope of the plate at the end to determine the twist in the angle and additional vertical deflection at the point of concern. Now, check the deflection against the limit. Hopefully it's still less than L/600 because there's more to add...

When the plate deflected back in toward the building, it pulled the angle back with it. So the distance between the center of mass of the brick and the shear center of the angle just got longer. So now run through the whole process again and see where you end up.

Keep doing this until you get convergence on the deflected shape of the assembly. If you get convergence with sufficient bearing of brick on steel and less than L/600 along the point of concern on the angle, then you're good. If you don't, or it doesn't converge at all, you have to try something different.

This is a lot of work. Especially when putting the shelf angle at the slab elevation and then using loose angles for window lintels could be designed in about 3 minutes.

 

[BAretired]

This thread reminds me of a story my boss told me in my first engineering job in 1955. A curved steel angle was used to carry brick veneer on a rounded corner of a small building in downtown Toronto, Ontario. The bricklayer installed a curved brick fascia, supported on the steel angle, then left for the day. Next morning, when he arrived at the site, the bricks were lying on the ground. He cursed the vandals, whoever they were, rebuilt the brick and placed a barricade around the work. On the following day, bricks were again lying on the ground.

The EOR determined that the brick was slowly rotating due to torsional stress in the angle, and corrective measures were taken to stiffen the structure, after which, the bricks remained in position.

BA

 

[MaxMedic]

There is no way this design is going to work, I am having it scrapped and changed.

 

[dik]

Maybe something like... I should have added that 600 lbs is not a massive load... small compared to those usually dealt with. You could use hanger angles every 3 or 4' and use 1/2 anchors? My favourites Hilti HAS E55 and 200 Hilti Hit-Hy adhesive.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[MaxMedic]

The vertical member is an angle, correct? If it is that is something along the lines of what I am thinking of

 

[KootK]

Another, imperfect option. It's a difficult situation that is usually heavily impacted by building envelope / thermal break concerns. And, from a building envelope perspective, most things push in the direction of loose lintels.

 

[dik]

Yup Just updated my comment.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

This has some nice mechanical advantages but thermal & constructability issues of its own.

 

[dik]

If thermal is a problem, I'd add a small plate to the angle and use Fabreeka separator with bolts... That how you get a real thermal break... often do it for exterior pipe racks connected through an existing building.(Added sketch)

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Veer007]

As a steel detailer, I have come up with this solution, without changing the original design, will it work for you?

Thanks in advance!!