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Brick veneer develop moment in steel Connection
2

Brick veneer develop moment in steel Connection

Brick veneer develop moment in steel Connection

(OP)
Hey Guys,

So far, my EOR has confirmed that bolted connection acceptable for this location, due to the Galv shelf angle my fabricator prefers the bolted connection, then what was the concern is, Will this connection resist the rotation which causes by brick veneer?

Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

It might, and they often do in practice, but these sort of connections are generally assumed as pins in design, and are assumed to rotate a little bit.

RE: Brick veneer develop moment in steel Connection

The two bolts provide a force couple that can resist moment. How well they resist the moment is another story. As Tomfh mentioned, these are usually assumed to rotate some and not transfer moment - at least not at ultimate loads. As long as everyone understands that a little slip is possible, which may cause the tip of the angle to rotate down and that movement is acceptable then there's nothing to worry about. It should be noted that the movement will not be gradual. It will be "fixed" until the load on the angle creates a moment that overcomes the static friction in the connection. Then it will go through its full rotation all at once - probably after there's several feet of brick already above the opening with mortar set up and getting brittle.

RE: Brick veneer develop moment in steel Connection

My guess is that you want some adjustment to align the veneer, but little to no angle rotation.

Can you provide short vertical slots and then pretension the bolts once aligned?

RE: Brick veneer develop moment in steel Connection

Seems to me to be a terrible design for the reasons already mentioned.

Sure IF it is designed as a slip-critical connection with the surfaces prepared suitably and the bolts torqued as needed then you can make this work but that doesn't seem like it is the case here.


RE: Brick veneer develop moment in steel Connection

(OP)
So both of the cases only resist shear force which causes by brick veneer,

However, it will not take little moment force even at ultimate loads,

Connection okay only until the static friction of bolts more than the moment created by veneer or need to be slip critical, right?

Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

(OP)

Quote (JLNJ)

Can you provide short vertical slots and then pretension the bolts once aligned?
We don't need to align these angles as these are shelf angles, So why has the bolted connection been provided for, Cos these are Galvanized angle but the beam to be painted.

Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

Veer007:
Why is the brick veneer set so far away from the stl. bm.? That eccentricity causes a fairly sizable torsion on the stl. bm., which must be accounted for in its design. Move the stl. bm. out or the brick veneer in to reduce this torsion. The shelf angle should be adjustable vertically and laterally, in and out, so as to make up for erection tolerances, and match the brick coursing, as the brick is brought up, and to keep the brick in its plane. Why not eliminate the attachment pls. and use two angles, back to back. The support angles at 48” o/c, have vert. slots on their vert. legs for vert. adjustment, and horiz. slots, in and out, in the horiz. leg which bears on the stl. bm. flg. for lateral adjustment.

RE: Brick veneer develop moment in steel Connection

Veer007,

You will discover that if you check an I shaped member for rotation along the length of the beam due to torsion it will twist like a limp spaghetti noodle and generate a very visible and normally unacceptable rotation. Use the AISC design guide for torsion, # 9 (I think) to verify the amount of rotational deflection with a max amount in the center of the beam and approximately zero at the ends of the beam. If you have to use a similar detail, you must use a box beam or an HSS beam.

Jim

RE: Brick veneer develop moment in steel Connection

dhengr - as energy codes evolve and architects put more and more insulation in the air gap between frame and veneer, the veneer moves further and further away. Most of the buildings I've done recently have required L6x4 (LLH) with barely half of the brick sitting out on the tip of the 6" leg. And I'm in a relatively mild climate (or at least we're supposed to be...I think we're at 3 weeks of heat index above 100degrees).

I'm curious about the adjustment suggestions. I've never seen that done in practice. How practical is it to adjust the angle alignment as the veneer is being built? What kind of situation really warrants that?

EDIT: one issue I do see is flashing. One of the reasons for the aforementioned L6x4 was to make sure the vertical leg of the angle is tight to the wall. It makes for much easier flashing. In this detail, the flashing may not work out so well. I realize you're the fabricator's engineer and that's not really your responsibility, per se, but if this is a design change that the fabricator is asking for it would be a good idea to make sure you get an approval from the architect as well as the EOR.

RE: Brick veneer develop moment in steel Connection

(OP)

Quote (phamENG)

Is my assumption below correct?

So both of the cases only resist shear force which causes by brick veneer,

However, it will not take little moment force even at ultimate loads,

Connection okay only until the static friction of bolts more than the moment created by veneer or need to be slip critical, right?

Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

No. I think they are saying ..

Your connection detail is theoretically a pinned type connection.
Theoretically connections are considered to resist moment only when beam flanges are directly connected to column flanges.
That connection is not so good for moment resisting. But with 2 bolts, it will resist some small amount of moment.

The connection maybe not the real problem.

The wall weight transferring through your connection is putting a torsional load on the beam.
That type of beam does not work for torsion loads.
Consider using a box shape beam.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

RE: Brick veneer develop moment in steel Connection

Not exactly. Do they take shear? Yes. Do they take moment? Sort of, but I would say not at ultimate. Unless it's slip critical, I would not count on any moment transfer in design. From a purely academic standpoint (or, perhaps, forensic) we can argue that there's friction etc. etc. but it doesn't do you too much good to dwell on it while making actual design decisions.

I agree with ax1e and others regarding the poor performance of an open section in torsion, but I also realize that you're the fabricator's engineer and don't have the authority to change the beam shape. Nor are you designing the beam.

RE: Brick veneer develop moment in steel Connection

Quote (phamENG)

Do they take moment? Sort of, but I would say not at ultimate. Unless it's slip critical,

How come it won't take moment? It only has to rotate a tiny mount before the bolts will take up bearing. This will get lost in the noise compared to the the twist that will be occurring in the I-beam.

RE: Brick veneer develop moment in steel Connection

This type of connection obviously will transfer some small amount of moment, as you suggest, but a relatively very small amount when compared to a true moment connection. As you point out, after some initial rotation, the bolt friction and bearing will bind the plates and moment will begin to be transferred. If the bending moment is small, within the margin of rotation, no moment is transferred. After lockup of the plates, the very short, limited distance between bolts quickly causes either slippage between plates, ie. rotation and no moment resistance, or bolt or plate failure from shear in the bolt and tension in the bolt hole edge distance. The end result is that, yes, it can transmit some bending moment, but only over a very narrow, limited range of values, which make it unsuitable for typical moment connections, where usual bending loads being resisted are orders of magnitude greater than the capacity that this "pinned end" connection has.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

RE: Brick veneer develop moment in steel Connection

Quote (phamENG)

Do they take moment? Sort of, but I would say not at ultimate

I keep hearing this. What does this really mean? Why is it OK to allow it to take shear but not moment?

RE: Brick veneer develop moment in steel Connection

Because they’re not rotationally rigid enough. By the time the bolts engage and form a couple the thing has already twisted too much.

RE: Brick veneer develop moment in steel Connection

Quote (Tomfh)

Because they’re not rotationally rigid enough. By the time the bolts engage and form a couple the thing has already twisted too much.

I get that. Does not seem like there would be that much rotation, however, with 1/16" oversized holes.
Why is the minor vertical translation from the shear OK but not the minor rotation?

RE: Brick veneer develop moment in steel Connection

Veer07,

As others have mentioned above, your problem is not the moment that the specific detail loads the beam, but it is the Torsion the eccentric load from the Masonry puts on the length of the beam. The degree of rotation is additive from the end connection too the midpoint of the beam and then decreases from the midpoint to the connection at the other end. The I section will rotate like a limp spaghetti noodle.

Jim H

RE: Brick veneer develop moment in steel Connection

Quote (XR250)

Why is the minor vertical translation from the shear OK but not the minor rotation?

A vertical slip of 1-2mm doesn’t generally matter.

A rotation of 1-2mm over a lever arm of say 80mm can be quite visually quite a lot.

RE: Brick veneer develop moment in steel Connection

Those connections will apply a uniform torsional moment with a moment arm from the midpoint of the brick veneer to the centroid of the support beam, W 200x59.

I didn't see any information about the length of that beam or about how many connectors there will be.

I can say from personal experience with this situation there will be substantial rotation from the first connection at the end of the beam, (zero rotation at the first end of the support beam) until the midpoint of the beam with a return to zero rotation at the other end of the support beam unless you use a box section or HSS support beam.

Jim H


RE: Brick veneer develop moment in steel Connection

There are two issues:

1. The Rotational rigidity of the connection itself. Many of us are focussing on that. The connection may rotate far more than allowed prior to the bolts engaging.

2. The Torsional stiffness of the main beam, which also may result in a rotation. I beams aren't great in torsion.

Both are worth thinking about.

RE: Brick veneer develop moment in steel Connection

Veer07,

Your problem has been identified by many, you should provide information of structures in adjacent to the edge beam, so someone may be able to come up a good idea. However, I would like to ask if you have posted a work drawing, or it was just a sketch of idea. I am particularly in knowing why the mixed use of unit - all seem in metric, but the designation of bolt, and wall thickness. I have noticed the trend in quite a few latest threads.

RE: Brick veneer develop moment in steel Connection

Quote (Tomfh)

Quote (A vertical slip of 1-2mm doesn’t generally matter.

A rotation of 1-2mm over a lever arm of say 80mm can be quite visually quite a lot.)


Looking at the geometry of this connection, worst case, approximately, the angle will rotate 2 mm downward from potential bolt slip - assuming none of that bolt hole tolerance was already taken up during erection. The overall deflection of the beam could be 1" or more and STILL meet code - not including the torsion that is going to occur. Does not seem like an issue.
Certainly not ideal, however.

RE: Brick veneer develop moment in steel Connection

Quote (XR250)

Looking at the geometry of this connection, worst case, approximately, the angle will rotate 2 mm downward from potential bolt slip - assuming none of that bolt hole tolerance was already taken up during erection. The overall deflection of the beam could be 1" or more and STILL meet code - not including the torsion that is going to occur. Does not seem like an issue.

It's the not the deflection relative to the overall span that's the concern with the connection. It's the rotational deflection. If the bolts can slip by 1-2mm then the connection can rotate out of plumb due to the short lever arm, potentially causing cracking/leaning of the brickwork.

RE: Brick veneer develop moment in steel Connection

(OP)

Quote (retired13)

I am particularly in knowing why the mixed use of unit - all seem in metric, but the designation of bolt, and wall thickness. I have noticed the trend in quite a few latest threads.

Apologies for the inconvenience, just to understand easily.
Bolt tolerance is 1/16"
Below snap will show more details, I have used STUB HSS102X102X6.4 at the column with 4-19Ø bolts where shelf angle passing the columns.


This is a multi-story building, the clearance between the floor is ±2950mm, 5 floors + Roof.
Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

(OP)
W-beams are going to support precast slab at the top, I think this is the reason why the EOR has not to prefer the BOX beams, Am I wrong?

Thanks in advance!!

RE: Brick veneer develop moment in steel Connection

Quote (Tomfh)

It's the not the deflection relative to the overall span that's the concern with the connection. It's the rotational deflection. If the bolts can slip by 1-2mm then the connection can rotate out of plumb due to the short lever arm, potentially causing cracking/leaning of the brickwork.

Tom,

I know I am being a PIA, but I feel like challenging a lot of these notions we have about situations. So why isn't L/360 deflection in a beam an issue for the brick yet a 1.5 mm rotation of the lintel an issue?

RE: Brick veneer develop moment in steel Connection

XR - my initial thought was along the lines of what Tom said. 1/32" of vertical deflection but the effective rotation could be quite a bit more. I looked back at the geometry and I'm less worried about that now as it doesn't appear to be that long (though the actual dimension isn't given). Still not excited about it, though. If you're dead on the deflection limit without that rotation, it could be a problem.

I'd say an L/360 deflection in the beam would be a huge problem. L/600 all day every day if it's supporting brick veneer.


RE: Brick veneer develop moment in steel Connection

Quote (phamENG)

I'd say an L/360 deflection in the beam would be a huge problem. L/600 all day every day if it's supporting brick veneer.

For sure. I use L/600 min.on new construction and L/1200 ish on new beams under existing masonry. Thought L/360 was allowed, however, but it looks like L/600 or 0.3" according to the BIA.

RE: Brick veneer develop moment in steel Connection

Do you have wall on top of the steel beam to support the veneer?

RE: Brick veneer develop moment in steel Connection

I hadn't thought of a more stringent requirement for old veneer on new beams. Makes sense, though. You have zero plasticity in the mortar joints to "adjust" to the gradual deflection so a tighter deflection requirement could be beneficial.

RE: Brick veneer develop moment in steel Connection

Quote (XR250)

I feel like challenging a lot of these notions we have about situations. So why isn't L/360 deflection in a beam an issue for the brick yet a 1.5 mm rotation of the lintel an issue?

A deflection of L/360 may be cause for concern when mortar cracks and needs re-pointing. Rotation is more difficult to predict precisely and is a much more serious issue if the brick slides off its support.

BA

RE: Brick veneer develop moment in steel Connection

What I and others are trying to say is that the deflection of the beam is calculated as l/360 or l/1200 down the length of the beam, but the rotation of the beam is applied as a degree of rotation per foot and continues to add up each foot until the midpoint of the beam. The I shaped beam will rotate like a twisted piece of cooked spaghetti.

I still have not seen a pounds per foot of torsional load or the length of the beam with no torsional restraint down the length of the beam.

Jim

RE: Brick veneer develop moment in steel Connection

Before adding the rotation of the beam, the flexibility of the bolt connection will rotate an amount that deserve attention. The sketches below show the deflection of tip of the angle due to bolts rotated into position against the bolt holes (a net 1/16" shift of the bolts). Further assume 20' angle span, L/600 = 0.4", the first case has consumed 42% the allowable, and 57.5% the second.



RE: Brick veneer develop moment in steel Connection

Quote:

How come it won't take moment? It only has to rotate a tiny mount before the bolts will take up bearing. This will get lost in the noise compared to the the twist that will be occurring in the I-beam.

A very small amount of rotation releases bending moment. A small amount of slippage does not release shear.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

RE: Brick veneer develop moment in steel Connection

Quote (XR250)

So why isn't L/360 deflection in a beam an issue for the brick yet a 1.5 mm rotation of the lintel an issue?

The 1.5mm rotation is relative to a bolt lever arm of ~80mm. ~L/50. This is too much rotation. Look at the sketch retired13 has done.

RE: Brick veneer develop moment in steel Connection

Quote (Veer)

Below snap will show more details

Where does the moment go?

Into the slab? Into those cleat plates at the end? They're pretty soft too.

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